CN112523461A

CN112523461A - Porous niobium carbide MXene/reduced graphene oxide base heating brick

Info

Publication number: CN112523461A
Application number: CN202011452807.0A
Authority: CN
Inventors: 吴立刚; 曹达平; 马宇飞; 叶德林; 李明; 李正博; 曾垂彬; 刘秋明
Original assignee: Guangdong Kangxi Technology Co Ltd
Current assignee: Guangdong Kangxi Technology Co Ltd
Priority date: 2020-12-11
Filing date: 2020-12-11
Publication date: 2021-03-19

Abstract

The invention provides a porous niobium carbide MXene/reduced graphene oxide base heating brick which comprises a heat-insulating layer, a porous niobium carbide MXene/reduced graphene oxide base heating film and a ceramic tile layer, wherein the porous niobium carbide MXene/reduced graphene oxide base heating film is clamped between the heat-insulating layer and the ceramic tile layer; the porous niobium carbide MXene/reduced graphene oxide-based heating film comprises a first transparent insulating layer, a porous niobium carbide MXene/reduced graphene oxide-based conductive film, a second transparent insulating layer and an electrode, wherein one end of the electrode is electrically connected with the porous niobium carbide MXene/reduced graphene oxide-based conductive film, and the other end of the electrode extends out of the first transparent insulating layer or the second transparent insulating layer. The porous niobium carbide MXene/reduced graphene oxide base warm brick has excellent electronic conduction performance, good flexibility and tensile resistance, excellent heat conduction performance, infrared emission performance, antibacterial performance and structural stability.

Description

Porous niobium carbide MXene/reduced graphene oxide base heating brick

Technical Field

The invention relates to the technical field of new materials, and particularly relates to a porous niobium carbide MXene/reduced graphene oxide base warm brick.

Background

Along with the trend of people to good and healthy life, the traditional heating system is improved, more economic and clean alternative energy is searched, and the development of a novel green low-carbon heating system is reluctant. An electric heating technology based on graphene infrared emission performance, namely graphene-based infrared heating ink and an infrared heating body technology thereof, provides an effective solution for solving the problems. Compared with the traditional heating methods such as coal burning, steam, hot air and resistance, the graphene heating method has the advantages of high heating speed, high electricity-heat conversion rate, automatic temperature control, convenience and rapidness in zone control, stability in heating, no noise in the heating process, low operation cost, relatively uniform heating, small occupied area, low investment and production cost, long service life, high working efficiency and the like, and is more beneficial to popularization and application. The energy-saving heating device replaces the traditional heating, has particularly remarkable electricity-saving effect, can generally save electricity by about 30 percent, and even can achieve 60 to 70 percent in individual occasions.

Graphene is a molecule formed by the passage of carbon atoms through sp²The hybridized orbitals form a hexagonal two-dimensional nano material which is in a honeycomb lattice structure and only has one layer of carbon atom thickness. The unique structure of graphene gives it a number of excellent properties, such as a high theoretical specific surface area (2630 m)²/g)、Ultra-high electron mobility (-200000 cm)²/v.s), high thermal conductivity (5300W/m.K), high Young's modulus (1.0TPa), and high light transmittance (97.7%), among others. By virtue of the advantages of the structure and the performance of the graphene, the graphene has a huge application prospect in the fields of energy storage and conversion devices, nano-electronic devices, multifunctional sensors, flexible wearable electronics, electromagnetic shielding, corrosion prevention and the like. In view of the flexibility and the conductive characteristic of graphene, the graphene slurry is added into the printing ink to prepare the conductive printing ink, and the graphene heating layer is further prepared by spraying and drying the printing ink to prepare the graphene heating body.

In the prior art, graphene is generally prepared into graphene slurry, ink or paint, and then prepared into a graphene heating coating and the like through a printing method. However, the graphene heating coating prepared by the methods has the defects of poor thickness controllability, uneven heat generation, large sheet resistance, general heat conducting property, limited infrared emissivity and the like, and the existing graphene heating coating has the problems of poor flexibility, low electric conductor concentration, easy embrittlement after long-term use and the like, so that the existing graphene heating coating is short in service life and is not suitable for long-term use.

Disclosure of Invention

In view of the above, the invention provides a porous niobium carbide MXene/reduced graphene oxide base floor heating brick, which solves the problems of poor controllability of a heating coating thickness, non-uniform heat generation, large sheet resistance, general heat conductivity, limited infrared emissivity, poor flexibility of a graphene heating coating, easy embrittlement after long-term use and the like of the existing floor heating brick.

The invention provides a porous niobium carbide MXene/reduced graphene oxide base heating brick which comprises a heat-insulating layer, a porous niobium carbide MXene/reduced graphene oxide base heating film and a ceramic tile layer, wherein the porous niobium carbide MXene/reduced graphene oxide base heating film is clamped between the heat-insulating layer and the ceramic tile layer;

the porous niobium carbide MXene/reduced graphene oxide-based heating film comprises a first transparent insulating layer, a porous niobium carbide MXene/reduced graphene oxide-based conductive film, a second transparent insulating layer and an electrode, wherein the first transparent insulating layer covers one surface of the porous niobium carbide MXene/reduced graphene oxide-based conductive film, the second transparent insulating layer covers the other surface of the porous niobium carbide MXene/reduced graphene oxide-based conductive film, one end of the electrode is electrically connected with the porous niobium carbide MXene/reduced graphene oxide-based conductive film, and the other end of the electrode extends out of the first transparent insulating layer or the second transparent insulating layer;

the preparation method of the porous niobium carbide MXene/reduced graphene oxide-based conductive film comprises the following steps:

preparing a working electrode: providing graphite powder and niobium aluminum carbide powder, grinding the graphite powder and the niobium aluminum carbide powder to a fineness of more than 200 meshes, wherein the mass ratio of the graphite powder to the niobium aluminum carbide powder is 1-8: 1, and mixing the graphite powder and the niobium aluminum carbide powder and pressing into a working electrode;

preparing a niobium carbide/graphite oxide material: fixing the working electrode in an electrolytic cell, adding electrolyte into the electrolytic cell to enable the working electrode to be immersed in the electrolyte, wherein the electrolyte is fluorine-containing anion liquid and is used as an etching agent, the working electrode is used as a positive electrode, voltage is applied to enable the fluorine-containing anion liquid to be ionized to generate fluorine free radicals, and after electrolysis is finished, centrifuging and collecting precipitates from the electrolyte to obtain the niobium carbide/graphite oxide material;

preparing a niobium carbide MXene/reduced graphene oxide dispersion liquid: dissolving the niobium carbide/graphite oxide material in isopropanol according to the mass-volume ratio of 50-500 mg/ml, performing probe ultrasound on the isopropanol containing the niobium carbide/graphite oxide material, centrifuging the isopropanol containing the niobium carbide/graphite oxide material at 8000-15000 rpm for 10-30 min after the probe ultrasound is finished, collecting precipitates, immersing the precipitates into a reducing reagent for reduction, centrifuging, collecting the precipitates, drying, dispersing the dried precipitates in a first dispersing agent, and performing water bath ultrasound to obtain a niobium carbide MXene/reduced graphene oxide dispersion solution;

preparing a particle resin slurry: providing and mixing particulate matter powder and a second dispersing agent, adding resin into the second dispersing agent while stirring the second dispersing agent to prepare particulate matter resin slurry, wherein the diameter of the particulate matter powder is 0.1-1 mu m, the concentration of the particulate matter powder is 10-100 mg/ml, and the concentration of the resin is 50-500 mg/ml;

preparing porous niobium carbide MXene/reduced graphene oxide-based conductive ink: mixing the granular resin slurry, the niobium carbide MXene/reduced graphene oxide dispersion liquid, the polyacrylonitrile-maleic anhydride copolymer and the stabilizer according to the mass ratio of 500: 1000-10000: 1-50: 5-20, transferring the mixture to a protective gas environment, stirring at a constant temperature of 65-85 ℃ until the volume is 1/2-1/6, and preparing the porous niobium carbide MXene/reduced graphene oxide-based conductive ink;

preparing a porous niobium carbide MXene/reduced graphene oxide-based conductive film: forming the porous niobium carbide MXene/reduced graphene oxide-based conductive ink into a film by adopting a printing, blade coating or printing mode, immersing the film into a dilute acid solution, washing and drying to obtain a porous niobium carbide MXene/reduced graphene oxide-based conductive film;

the niobium aluminum carbide powder is Nb₃AlC₂Powder or Nb₄AlC₃And the particle powder is carbonate powder or metal oxide powder.

The porous niobium carbide MXene/reduced graphene oxide-based floor heating brick comprises a heat-insulating layer, a porous niobium carbide MXene/reduced graphene oxide-based heating film and a ceramic brick layer, wherein the porous niobium carbide MXene/reduced graphene oxide-based heating film is clamped between the heat-insulating layer and the ceramic brick layer. During the use, with this warm brick of porous niobium carbide MXene/reduction oxidation graphite alkene base flatly spread on indoor subaerial, heat preservation down and the ceramic tile layer up, the heat preservation has comparable thermal-insulated heat preservation effect, prevents that the heat from diffusing from the below, and the ceramic tile layer has good heat conductivility, guarantees from this that the heat that porous niobium carbide MXene/reduction oxidation graphite alkene base heating film produced does not flow outward, concentrates on the heat dissipation of ceramic tile layer surface, the increase of thermal efficiency. The ceramic tile layer has good insulation and waterproof effects, the wires and the circuit connecting terminals can also penetrate through the heat insulation layer to be electrically connected with the porous niobium carbide MXene/reduced graphene oxide-based heating film, water leakage and electric leakage can be effectively prevented, and the ceramic tile layer has high safety.

The porous niobium carbide MXene/reduced graphene oxide-based heating film comprises a first transparent insulating layer, a porous niobium carbide MXene/reduced graphene oxide-based conductive film, a second transparent insulating layer and an electrode, wherein the first transparent insulating layer and the second transparent insulating layer respectively cover two sides of the porous niobium carbide MXene/reduced graphene oxide-based conductive film to achieve an insulating protection effect, and the electrode is used for supplying power to the porous niobium carbide MXene/reduced graphene oxide-based conductive film. The porous niobium carbide MXene/reduced graphene oxide-based heating film has excellent electronic conduction performance, good flexibility and tensile resistance, excellent heat conduction performance, infrared emission performance, antibacterial performance and structural stability, so that the porous niobium carbide MXene/reduced graphene oxide-based heating brick has good heat conduction performance, infrared emission performance, antibacterial performance and long-term use stability. In addition, the porous niobium carbide MXene/reduced graphene oxide-based heating film can release 5-14 micron far infrared light waves after being electrified, and the light waves in the wave band can activate biomolecules such as nucleic acid proteins of a human body and the like, so that the porous niobium carbide MXene/reduced graphene oxide-based heating film has a physical therapy health-care effect on the human body; and the graphene molecules move violently, parasitic capacitance does not exist in the molecules, and the electric conversion efficiency is high.

The preparation method of the porous niobium carbide MXene/reduced graphene oxide-based conductive film comprises the steps of preparing a working electrode, preparing a niobium carbide/graphite oxide material, preparing a niobium carbide MXene/graphene oxide dispersion liquid, preparing a particulate resin slurry, preparing a niobium carbide MXene/graphene oxide ink and preparing the porous niobium carbide MXene/reduced graphene oxide-based conductive film. In the working electrode preparation step, graphite powder and niobium-aluminum carbide powder are mixed to be used as a working electrode, and the working electrode is used as an etching base material for subsequent electrolytic etching. The ratio of the graphite powder to the niobium-aluminum carbide powder can also control the ratio of niobium carbide MXene, reduced graphene oxide and graphite powder which are prepared subsequently, the niobium carbide MXene, reduced graphene oxide and graphite powder which are not completely stripped can improve the conductivity, dispersion effect and conductivity uniformity of the conductive ink, and the effect of promoting the stripping and dispersion of the niobium carbide MXene and the graphene oxide can be achieved.

The working electrode is fixed in an electrolytic cell, fluorine-containing anion liquid is ionized near the anode to generate fluorine free radicals (F), the fluorine free radicals etch graphite powder on the surface of the electrode to enable the graphite powder to fall off from the electrode, and at the moment, a large number of active groups such as hydroxyl groups are formed on the surface of the graphite powder to play a role in primarily stripping the graphite powder. Meanwhile, the fluorine free radicals also etch the metal aluminum in the niobium aluminum carbide powder, and the niobium aluminum carbide powder is separated from the electrode and forms flaky multilayer net-shaped niobium carbide. Graphite powder and niobium aluminum carbide powder are doped and distributed, and the graphite powder and the niobium aluminum carbide powder can be etched simultaneously in the fluorine free radical etching process, so that the stripping efficiency of the graphite powder and the niobium aluminum carbide powder is improved, and the subsequent preparation of graphene oxide and niobium carbide MXene is facilitated. And further dissolving the niobium carbide/graphite oxide material in isopropanol (stripping dispersion liquid) to carry out probe ultrasonic liquid phase stripping, carrying out common probe ultrasonic treatment on the preliminarily stripped multilayer net-shaped niobium carbide and the preliminarily stripped graphite powder, further stripping the multilayer net-shaped niobium carbide to obtain niobium carbide MXene, and stripping the graphite powder to obtain graphene oxide. The pulse oscillation process of probe ultrasound can realize the generation of niobium carbide MXene and graphene oxide, and can ensure that the power is not too high, so that the prepared sheet is incomplete and has too small size. The multilayer net-shaped niobium carbide is poor in dispersibility in stripping dispersion liquid, the preliminarily stripped graphene is added into the stripping dispersion liquid of the multilayer net-shaped niobium carbide, probe ultrasound is carried out together, the multilayer net-shaped niobium carbide is effectively stripped to form niobium carbide MXene under the assistance of the preliminarily stripped graphene, graphite powder is stripped to form graphene oxide, and the niobium carbide MXene and the graphene oxide can be promoted to be well doped in the common stripping process to prevent re-stacking. And centrifuging isopropanol containing the niobium carbide/graphite oxide material, collecting precipitate, wherein the precipitate comprises niobium carbide MXene, graphene oxide and graphite powder which is not completely stripped, and immersing the precipitate into a reducing reagent for reduction, so that the graphene oxide is reduced into reduced graphene oxide, and the effect of stabilizing the lamellar structure of the graphene and the niobium carbide MXene is achieved. And centrifuging the reduced mixed solution again, collecting the precipitate, drying, dispersing the dried precipitate in a first dispersing agent, and further dispersing the niobium carbide MXene, the graphene oxide and the graphite powder which is not completely stripped in the first dispersing agent by water bath ultrasound to obtain the niobium carbide MXene/reduced graphene oxide dispersion liquid.

In the step of preparing the particulate resin slurry, the particulate powder and the second dispersant are mixed, and the resin is added to the second dispersant while stirring the second dispersant to prepare the particulate resin slurry. The second dispersing agent can promote the good mixing of the resin and the particle powder and also can effectively promote the mixing and dissolution of the particle resin slurry and the niobium carbide MXene/reduced graphene oxide dispersion liquid. The particulate powder is carbonate powder or metal oxide powder, and after the conductive film is formed by printing, printing or coating, the particulate powder is mostly fixed on the surface of the conductive film due to the thin film layer. After film formation, the conductive film is immersed in an acid solution, surface particle powder is dissolved in an acid liquid to enable the conductive film to form a surface porous structure, the cleaned and dried conductive film has the surface porous structure, the surface infrared emission amount of the conductive film is higher, the heat release of the conductive film is facilitated, and the thermal conductivity is higher.

In the step of preparing the niobium carbide MXene/reduced graphene oxide-based conductive ink, the granular resin slurry, the niobium carbide MXene/reduced graphene oxide dispersion liquid, the polyacrylonitrile-maleic anhydride copolymer and the stabilizer are uniformly mixed in a constant-temperature water bath mode, meanwhile, the niobium carbide MXene and the reduced graphene oxide can be promoted to be connected with active groups on the surfaces of resin particles in a heating process, so that the conductive particles with high conductivity of the niobium carbide MXene and high flexibility of the reduced graphene oxide are formed, and finally, the film is formed by means of the resin particles. The single niobium carbide MXene has poor flexibility and is easy to oxidize, the conductive capacity of the oxidized MXene is reduced rapidly, the niobium carbide MXene and the reduced graphene oxide can be promoted to be peeled and dispersed in the process of peeling together, the niobium carbide MXene and the reduced graphene oxide are blended in the printing ink, and the effects of preventing the niobium carbide MXene from being oxidized and enhancing the flexibility of the conductive film are achieved by virtue of the high conductivity and flexibility of the reduced graphene oxide and the reductive protection effect of the stabilizer. The polyacrylonitrile-maleic anhydride copolymer has the main functions of harmonizing the uniformity of the ink, reducing the viscosity and surface tension of the ink, and simultaneously playing the roles of maintaining the long-term stability of the ink structure and preventing brittle fracture in the using process.

Preferably, the heat-insulating layer is made of polyurethane;

in the process of preparing the porous niobium carbide MXene/reduced graphene oxide base warm brick, the porous niobium carbide MXene/reduced graphene oxide base heating film is placed in an upper die cavity, a polyurethane base material is placed in a lower die cavity, the upper die cavity and the lower die cavity are buckled while the polyurethane base material is heated and foamed, a heating and insulating layer formed by integrally forming the porous niobium carbide MXene/reduced graphene oxide base heating film and the insulating layer is prepared, and finally the ceramic brick layer is bonded with the porous niobium carbide MXene/reduced graphene oxide base heating film to prepare the porous niobium carbide MXene/reduced graphene oxide base warm brick. The polyurethane heat-insulating layer is prepared through integrated foaming molding, the porous niobium carbide MXene/reduced graphene oxide-based heating film is tightly combined with the heat-insulating layer, and the secondary bonding procedure between the porous niobium carbide MXene/reduced graphene oxide-based heating film and the heat-insulating layer is reduced.

Preferably, in the step of preparing the working electrode, the graphite powder and the niobium aluminum carbide powder are ground to 300-mesh fineness, and the mass ratio of the graphite powder to the niobium aluminum carbide powder is 2-6: 1. The graphite powder and the niobium-aluminum carbide powder are ground to 300-mesh fineness, so that the graphite powder and the niobium-aluminum carbide powder can be efficiently etched in the subsequent etching process, the doping of the preliminarily stripped multilayer net-shaped niobium carbide and the preliminarily stripped graphite powder can be promoted, and the subsequent stripping process is facilitated.

Preferably, in the step of preparing the niobium carbide/graphite oxide material, the fluorine-containing anion liquid is an organic solvent containing fluorine anions, wherein the fluorine-containing anions in the fluorine-containing anion liquid are at least one of tetrafluoroborate ions and hexafluorophosphate ions. The tetrafluoroborate ions and the hexafluorophosphate ions are organic fluorine-containing anions, and can be ionized to generate fluorine free radicals in the ionization process of the tetrafluoroborate ions and the hexafluorophosphate ions in the electrolysis process, and the fluorine free radicals only remain near the anode, so that the electrolyzed water is prevented from generating hydrogen ions, graphite powder and niobium aluminum carbide powder are etched through the fluorine free radicals, and meanwhile, the organic solvent containing the fluorine anions has a certain protective effect on the preliminarily etched multilayer network structure niobium carbide.

Preferably, in the step of preparing the niobium carbide/graphite oxide material, the fluorine-containing anion liquid includes at least one of 1-ethyl-3-methylimidazole tetrafluoroborate, 1-ethyl-3-methylimidazole hexafluorophosphate, 1-butyl-3-methylimidazole tetrafluoroborate, 1-butyl-3-methylimidazole hexafluorophosphate, 1-octyl-3-methylimidazole tetrafluoroborate, 1-octyl-3-methylimidazole hexafluorophosphate, 1-hexyl-3-methylimidazole tetrafluoroborate and 1-hexyl-3-methylimidazole hexafluorophosphate. Therefore, by selecting the fluorine-containing organic salt, the fluorine-containing organic salt can be effectively dissolved in an organic solvent, a good mass transfer function is realized, fluorine free radicals can be generated by high-efficiency ionization, and the normal operation of an etching process is ensured.

Preferably, in the step of preparing the niobium carbide/graphite oxide material, the organic solvent of the organic solvent containing fluoride anion is at least one of acetonitrile, ethanol, isopropanol, acetone, N-methylpyrrolidone, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran and dichloromethane. Therefore, efficient mass transfer can be ensured through the organic solvent, fluorine-containing anions in the electrolyte can be promoted to be electrophoresed to the vicinity of the positive electrode for ionization to generate fluorine radicals, and the fluorine radicals are active and can only exist temporarily, namely the fluorine radicals only exist in the vicinity of the electrode and not in all electrolyte of the electrolytic cell, so that the electrode can be efficiently etched, and the effect of protecting the primarily stripped multilayer net-shaped structure niobium carbide can be achieved.

Preferably, in the step of preparing the niobium carbide/graphite oxide material, the concentration of the fluorine-containing anion liquid is 1-3 mol/L, the voltage is + 4-10V, and the electrolysis time is 5-15 h;

the temperature of the electrolyte in the electrolysis process is 35-45 ℃, the electrolyte is continuously stirred in the electrolysis process, and the stirring revolution is 150-300 rpm. The proper fluorine-containing anion concentration, voltage, electrolysis time and temperature can promote the etching process, and can prevent the excessive etching from reducing the yield of the graphene oxide and the niobium carbide MXene. The continuous stirring of the electrolyte in the electrolysis process can promote the graphite powder and niobium-aluminum carbide powder which are initially stripped to be rapidly separated from the electrode area (namely the fluorine radical etching area), and the function of preventing excessive etching is achieved.

More preferably, in the step of preparing the niobium carbide/graphite oxide material, the fluorine-containing anion liquid has a concentration of 2 mol/L, the voltage is + 6V, and the electrolysis time is 10 h.

Preferably, in the step of preparing the niobium carbide/graphite oxide material, the electrolyte is sieved by a 400-mesh sieve and then centrifuged to collect precipitates, wherein the centrifugation speed is 5000-10000 rpm, and the centrifugation time is 20-60 min. The electrolyte can be effectively removed by sieving the electrolyte with a 400-mesh sieve, so that the efficiency of subsequent liquid-phase ultrasonic stripping is improved, the electrolyte and the liquid-phase ultrasonic stripping can also promote the mixing of graphite powder, graphene and niobium carbide, and the electrolyte is centrifugally collected and precipitated for the subsequent stripping process.

Preferably, in the step of preparing the niobium carbide MXene/reduced graphene oxide dispersion liquid, the ultrasonic power of the probe is 300-500W, the ultrasonic time of the probe is 3-10 h, and the temperature of isopropanol of the niobium carbide/graphite oxide material in the ultrasonic process of the probe is lower than 15 ℃. After the etching process, the graphite powder and the niobium-aluminum carbide powder are easier to be stripped into flaky nano materials. The isopropanol used as the dispersion liquid has a good dispersion effect, has the effect of stabilizing the structures of the niobium carbide MXene and the graphene oxide, and prevents the niobium carbide MXene or the graphene oxide from being stacked or agglomerated again. In the ultrasonic process of the probe, the multi-layer net-shaped structure niobium carbide can be effectively stripped to form niobium carbide MXene and graphite is stripped to form graphene oxide by means of pulse ultrasonic waves, the graphene oxide and the niobium carbide MXene are ultrasonically stripped together, the stripping efficiency of the graphene oxide and the niobium carbide MXene is improved, and on the other hand, the stripped graphene oxide and the niobium carbide MXene are uniformly doped, so that the probe has the functions of protecting the niobium carbide MXene and preventing the niobium carbide MXene from being oxidized and degraded.

Preferably, the working frequency of the probe ultrasound is set to work for 5 s and pause for 5 s. The ultrasonic frequency setting of the probe ultrasonic can effectively promote the stripping of the graphene oxide and the niobium carbide MXene, and meanwhile, the local temperature rise and degradation caused by the continuous ultrasonic process can be avoided.

Preferably, the reducing agent is at least one of hydroiodic acid, hydrazine hydrate, ascorbic acid, and sodium borohydride. The reduction of graphene oxide in the precipitate to reduced graphene oxide can be promoted by the reducing reagent, and the niobium carbide MXene also has a certain stabilizing effect.

Preferably, the power of the water bath ultrasound is 200-300W, the time of the water bath ultrasound is 8-24 h, and the temperature of the first dispersing agent in the water bath ultrasound process is lower than 15 ℃. The proper power, time and temperature of the water bath ultrasound can ensure that the graphite powder, the reduced graphene oxide and the niobium carbide MXene are uniformly dispersed in the first dispersing agent, and the effect of stabilizing the structure of the niobium carbide MXene is achieved.

Preferably, the first dispersant is one or more of propylene glycol, cyclohexanol, terpineol, ethanol, ethylene glycol and isopropanol. The first dispersing agent plays a role in dispersing graphite powder, reduced graphene oxide and niobium carbide MXene, and when the uniformly dispersed graphite powder, reduced graphene oxide and niobium carbide MXene are mixed with other components in the printing ink, the uniformly dispersed graphite powder, reduced graphene oxide and niobium carbide MXene are conveniently dispersed, and the overall uniformity of the printing ink is improved.

Preferably, in the step of preparing the resin slurry of particulate matter, the second dispersant is a cellulose derivative, and the cellulose derivative is one or more of methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, cellulose acetate and cellulose nitrate in combination. The second dispersing agent plays a role in promoting mixing and dispersion of the particulate powder and the resin, the particulate powder and the resin are dispersed in advance through the second dispersing agent, and then the particulate resin slurry is mixed with the niobium carbide MXene/reduced graphene oxide dispersion liquid to promote uniform mixing of the whole printing ink, so that the surface porous structure (the porous structure formed after pickling) of the film-formed conductive film is more uniform, the infrared ray release amount, the conductivity and the heat conductivity of the unit area are higher, and the local temperature is prevented from being too high.

Preferably, in the step of preparing the particulate resin slurry, the resin is one or more of epoxy resin, polydimethylsiloxane resin, polycarbonate resin, polyurethane resin, acrylic resin, waterborne alkyd resin, phenolic resin and silicone-acrylic resin. The conductive ink has the advantages that the film forming effect of the resin is beneficial to the overall film forming of the conductive ink, the resin has certain flexibility and brittle fracture resistance after film forming, and the conductive film after film forming has excellent flexibility, brittle fracture resistance and adhesion performance and can be attached to a required substrate to form a film based on requirements.

Preferably, in the step of preparing the porous niobium carbide MXene/reduced graphene oxide ink, the stabilizer comprises at least one of ethylenediamine, propylenediamine, hexamethylenediamine, phenylenediamine, glycine, 6-aminocaproic acid and octadecylamine. The stabilizer has the functions of stabilizing niobium carbide MXene and reducing graphene oxide structures, and maintains the long-term stability of ink structures, conductivity, infrared emissivity and the like.

Preferably, in the step of preparing the porous niobium carbide MXene/reduced graphene oxide ink, the protective gas is nitrogen or argon. The niobium carbide MXene/reduced graphene oxide ink is protected by protective gas in the heating and mixing process, so that the niobium carbide MXene is prevented from being oxidized or degraded, and the whole structure of the ink is protected to a certain extent. After the niobium carbide MXene/reduced graphene oxide ink is solidified and formed into a film, the reduced graphene oxide ink and the niobium carbide MXene are mutually doped and sealed in resin, so that the protective effect is quite good.

Preferably, in the step of preparing the porous niobium carbide MXene/reduced graphene oxide ink, stirring at a constant temperature of 75 ℃ until the volume is concentrated to 1/4 to prepare the porous niobium carbide MXene/reduced graphene oxide-based conductive ink. The prepared porous niobium carbide MXene/reduced graphene oxide-based conductive ink has proper viscosity, density and conductivity, and the film thickness and the leveling property of a film can be conveniently controlled.

Preferably, a non-layered molybdenum nanosheet/graphene-based fiber film is further arranged between the second transparent insulating layer and the porous niobium carbide MXene/reduced graphene oxide-based conductive film, and the preparation method of the non-layered molybdenum nanosheet/graphene-based fiber film comprises the following steps:

preparing a pre-stripping dispersion of molybdenum powder: providing molybdenum powder and adding the molybdenum powder into the pre-stripping dispersion liquid, performing primary water bath ultrasound on the pre-stripping dispersion liquid added with the molybdenum powder, wherein the temperature of the primary water bath ultrasound is 5-15 ℃, and centrifuging and collecting supernatant after the ultrasound is finished to prepare the pre-stripping dispersion liquid of the molybdenum powder;

preparing a mixture of molybdenum powder and graphene oxide: adding graphene oxide into a pre-stripping dispersion liquid of molybdenum powder, performing secondary water bath ultrasound, wherein the temperature of the secondary water bath ultrasound is 5-15 ℃, centrifuging after the ultrasound is finished, collecting a bottom layer mixture, dispersing the bottom layer mixture in water, washing and drying to obtain a mixture of the molybdenum powder and the graphene oxide;

preparing a non-layered molybdenum nanosheet/graphene oxide dispersion liquid: dispersing a mixture of molybdenum powder and graphene oxide in N-methyl pyrrolidone to prepare a mixed solution, performing ultrasonic treatment on the mixed solution by using a pulse probe, wherein the ultrasonic temperature of the pulse probe is 5-15 ℃, and concentrating the mixed solution after the ultrasonic treatment is finished to prepare a non-layered molybdenum nanosheet/graphene oxide dispersion solution;

spinning: adding PI powder into a non-layered molybdenum nanosheet/graphene oxide dispersion liquid, transferring the dispersion liquid into an oil bath kettle at the temperature of 103-110 ℃, uniformly stirring the dispersion liquid to serve as a spinning stock solution, and performing electrostatic spinning and collection by using a spinning needle with the inner diameter increased along the filament outlet direction to prepare a non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane;

and (3) post-treatment: washing the non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane, drying and reducing to obtain a non-layered molybdenum nanosheet/graphene-based fiber membrane;

the mass of the graphene oxide is 0.5-5 times of that of molybdenum powder in a pre-stripping dispersion liquid of the molybdenum powder, the mass fraction of PI in the spinning stock solution is 8-12%, and the pre-stripping dispersion liquid is isopropanol, deionized water or a mixed solution of the isopropanol and the deionized water.

The preparation method of the non-layered molybdenum nanosheet/graphene-based fiber membrane comprises the steps of preparing a pre-stripping dispersion liquid of molybdenum powder, preparing a mixture of the molybdenum powder and graphene oxide, preparing the non-layered molybdenum nanosheet/graphene oxide dispersion liquid, spinning and post-treating. The step of preparing the pre-stripping dispersion liquid of the molybdenum powder can strip the molybdenum powder in advance, and the stripping efficiency of the molybdenum powder and the preparation efficiency of the non-layered molybdenum nanosheets are improved by collecting the primarily stripped molybdenum powder and using the primarily stripped molybdenum powder for the next stripping. In the step of preparing the mixture of the molybdenum powder and the graphene oxide, the preliminarily peeled molybdenum powder and the graphene oxide are subjected to water bath ultrasound together, so that the molybdenum powder is poor in dispersibility in the pre-peeling dispersion liquid, the graphene is added into the pre-peeling dispersion liquid of the molybdenum powder and the water bath ultrasound is carried out together, and the molybdenum powder is effectively peeled and can be well mixed with the graphene oxide with the aid of the graphene. In the step of preparing the non-layered molybdenum nanosheet/graphene oxide dispersion liquid, the mixed liquid is subjected to ultrasonic treatment by adopting a pulse probe, so that the non-layered molybdenum nanosheets can be effectively prepared, and the non-layered molybdenum nanosheets and the graphene oxide dispersion liquid are further mixed, so that the phenomenon that the non-layered molybdenum nanosheets are stacked mutually to cause overhigh local concentration and cannot be spun is prevented, and the conductivity and the dispersion uniformity among graphene layers can be improved. The first-stage water bath ultrasound, the second-stage water bath ultrasound and the pulse probe ultrasound are carried out at low temperature, so that the prepared non-layered molybdenum nanosheets can be effectively prevented from being degraded. In the spinning step, the PI powder is added into the non-layered molybdenum nanosheet/graphene oxide dispersion liquid, and the mixture is subjected to oil bath and stirring to be uniformly mixed, so that the electric conductor is fully doped on the PI high molecular compound, the physical size and performance of the spun yarn are ensured to be uniform, and the electric conductor of the spun fiber is uniformly distributed and has uniform electric conductivity. In the post-treatment step, the non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane is washed, dried and reduced, and the graphene oxide is reduced to reduced graphene oxide, so that the reduced non-layered molybdenum nanosheet/graphene-based fiber membrane is prepared, and has the advantages of stable chemical property, heat resistance, strong electric conductivity, high thermal conductivity, high infrared radiation rate and the like. Compared with a non-layered molybdenum nanosheet/graphene-based fiber film, the porous niobium carbide MXene/reduced graphene oxide-based conductive film is smaller in resistance, large in current and more in heat generation, and the porous niobium carbide MXene/reduced graphene oxide-based conductive film is arranged on the non-layered molybdenum nanosheet/graphene-based fiber film to play a role in rapid heat conduction, so that heat generated by the porous niobium carbide MXene/reduced graphene oxide-based conductive film is rapidly conducted out, and local heat accumulation is prevented. In addition, the non-layered molybdenum nanosheet/graphene-based fiber film also has the effects of high infrared radiation, high flexibility, bending resistance and the like, and can enhance the infrared radiance, the flexibility and the bending resistance of the porous niobium carbide MXene/reduced graphene oxide-based heating film.

Preferably, in the step of preparing the non-layered molybdenum nanosheet/graphene oxide dispersion, the mass-to-volume ratio of the mixture of molybdenum powder and graphene oxide to N-methylpyrrolidone is 5 mg/ml, the time of the pulse probe ultrasound is 8 hours, the power of the pulse probe ultrasound is 250W, and the frequency of the pulse probe ultrasound is set as follows: ultrasound 5 s, interval 5 s. Therefore, the mixture of molybdenum powder and graphene oxide can be promoted to be well dispersed in N-methyl pyrrolidone by the aid of pulse probe ultrasound, and a dispersion liquid with well dispersed non-layered molybdenum nanosheets and graphene oxide is prepared to prepare a spinning stock solution for subsequent preparation.

Preferably, in the post-treatment step, the non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane is washed by deionized water for 3 times, and the non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane is transferred to a vacuum drying oven at 70 ℃ for drying for 8 hours;

soaking the dried non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane in HI and NaBH₄And hydrazine hydrate and ascorbic acid are reduced to prepare the non-layered molybdenum nanosheet/graphene-based fiber membrane. And removing residual N-methyl pyrrolidone in the non-layered molybdenum nanosheets/graphene-based fiber membrane through washing and drying processes to prepare the PI/non-layered molybdenum nanosheets/graphene oxide hybrid porous fiber membrane, wherein the washed and dried PI/non-layered molybdenum nanosheets/graphene oxide hybrid porous fiber membrane has higher porosity and larger specific surface area and flexibility. And finally, the graphene oxide is reduced into reduced graphene oxide through a reduction process, and the reduced non-layered molybdenum nanosheet/graphene-based fiber membrane has better environmental stability and heat resistance, so that the service life of the non-layered molybdenum nanosheet/graphene-based fiber membrane is effectively prolonged.

Preferably, a waterproof bonding layer is further arranged between the first transparent insulating layer and the second transparent insulating layer, and the waterproof bonding layer is bonded with the first transparent insulating layer and the second transparent insulating layer respectively to form a closed cavity;

the porous niobium carbide MXene/reduced graphene oxide-based conductive film and the non-layered molybdenum nanosheet/graphene-based fiber film are arranged in the closed cavity, and the electrode extends out of the closed cavity. The first transparent insulating layer and the second transparent insulating layer are respectively bonded with the waterproof bonding layer to form a closed cavity, and the porous niobium carbide MXene/reduced graphene oxide-based conductive film and the non-layered molybdenum nanosheet/graphene-based fiber film are arranged in the closed cavity, so that a good insulating and waterproof effect is achieved.

Preferably, the electrode comprises a transverse arm and a vertical arm which are connected with each other, the transverse arm extends out of the closed cavity from the non-layered molybdenum nanosheet/graphene-based fiber film, and the vertical arm extends out of the non-layered molybdenum nanosheet/graphene-based fiber film and is electrically connected with the porous niobium carbide MXene/reduced graphene oxide-based conductive thin film. The electrode is set to be L-shaped and comprises a transverse arm and a vertical arm which are connected with each other, the porous niobium carbide MXene/reduced graphene oxide-based conductive film can be electrically connected with an external power supply by virtue of the L-shaped electrode, and a closed waterproof cavity can be formed in an L-shaped loop, so that the waterproof performance of the porous niobium carbide MXene/reduced graphene oxide-based conductive film is facilitated.

Preferably, a heat reflecting layer is further arranged between the first transparent insulating layer and the porous niobium carbide MXene/reduced graphene oxide-based conductive film, and the heat reflecting layer is arranged in a concave shape to form an accommodating groove;

one surface of the non-layered molybdenum nanosheet/graphene-based fiber membrane is embedded into the accommodating groove, the non-layered molybdenum nanosheet/graphene-based fiber membrane and the accommodating groove enclose a cavity, and the porous niobium carbide MXene/reduced graphene oxide-based conductive film is arranged in the cavity. The heat reflecting layer arranged in a concave shape covers the porous niobium carbide MXene/reduced graphene oxide-based conductive film and part of the non-layered molybdenum nanosheets/graphene-based fiber film, so that the porous niobium carbide MXene/reduced graphene oxide-based conductive film and the non-layered molybdenum nanosheets/graphene-based fiber film can only radiate heat from the opening direction of the heat reflecting layer when being electrified to generate heat, and the heat reflecting layer has the effects of restraining the infrared radiation direction, controlling the heat conduction direction and improving the heat utilization rate.

Preferably, the porous niobium carbide MXene/reduced graphene oxide-based conductive thin film comprises a plurality of porous niobium carbide MXene/reduced graphene oxide-based conductive thin film monomers arranged side by side, and correspondingly, the non-layered molybdenum nanosheet/graphene-based fiber film comprises a plurality of non-layered molybdenum nanosheet/graphene-based fiber film monomers arranged side by side;

a non-layered molybdenum nanosheet/graphene-based fiber membrane monomer is arranged between any porous niobium carbide MXene/reduced graphene oxide-based conductive membrane monomer and the second transparent insulating layer. Therefore, by arranging a plurality of groups of porous niobium carbide MXene/reduced graphene oxide-based conductive film monomers and non-layered molybdenum nanosheets/graphene-based fiber film monomers, each porous niobium carbide MXene/reduced graphene oxide-based conductive film monomer is arranged in parallel, the heat generation effect of the whole heating film can be effectively prevented from being influenced after the single porous niobium carbide MXene/reduced graphene oxide-based conductive film monomer is broken, the rear-end process can be randomly cut according to different product lengths, and the purpose of one film is achieved. Each porous niobium carbide MXene/reduced graphene oxide-based conductive film monomer corresponds to a non-layered molybdenum nanosheet/graphene-based fiber film monomer, and the non-layered molybdenum nanosheet/graphene-based fiber film monomer can conduct heat and electricity, can promote the heat release of the porous niobium carbide MXene/reduced graphene oxide-based heating film, and can also effectively prevent the open circuit of the porous niobium carbide MXene/reduced graphene oxide-based heating film.

Preferably, a plurality of square holes are uniformly distributed at two ends of any porous niobium carbide MXene/reduced graphene oxide-based conductive film monomer, so that the impedance of each section of graphene heating coating can be controlled within a standard range in the production process, and the safe current carrying is more reliable.

Advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of embodiments of the invention.

Drawings

In order to more clearly illustrate the contents of the present invention, a detailed description thereof will be given below with reference to the accompanying drawings and specific embodiments.

Fig. 1 is an exploded view of a porous niobium carbide MXene/reduced graphene oxide-based warm brick provided in an embodiment of the present invention;

FIG. 2 is an exploded view of the porous niobium carbide MXene/reduced graphene oxide-based heating film shown in FIG. 1;

fig. 3 is a schematic longitudinal sectional view of the porous niobium carbide MXene/reduced graphene oxide-based heating film in fig. 2.

Detailed Description

While the following is a description of the preferred embodiments of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

As shown in fig. 1, the porous niobium carbide MXene/reduced graphene oxide based warm brick is an embodiment of the present invention. The porous niobium carbide MXene/reduced graphene oxide-based floor heating brick sequentially comprises a tile layer 01, a porous niobium carbide MXene/reduced graphene oxide-based heating film 02 and a heat preservation layer 03 from top to bottom, wherein the porous niobium carbide MXene/reduced graphene oxide-based heating film 02 is clamped between the tile layer 01 and the heat preservation layer 03.

The preparation method of the porous niobium carbide MXene/reduced graphene oxide base warm brick comprises the following steps:

the preparation process comprises the following steps: weighing polyurethane black materials and white materials, uniformly mixing the polyurethane black materials and the white materials, injecting the mixture into a lower die cavity, placing the porous niobium carbide MXene/reduced graphene oxide-based heating film connecting wires into an upper die cavity, carrying out chemical reaction on the uniformly mixed polyurethane black materials and the polyurethane white materials in the lower die cavity, heating for foaming, buckling the lower die cavity onto the upper die cavity, and integrally forming the porous niobium carbide MXene/reduced graphene oxide-based heating film and foamed polyurethane to obtain the heating insulation board.

The ceramic tile layer is compounded with the heating insulation board: and spraying a proper amount of adhesive on the bottom of the ceramic tile layer, and then adhering the ceramic tile layer with the porous niobium carbide MXene/reduced graphene oxide-based heating film of the heating insulation board to obtain the porous niobium carbide MXene/reduced graphene oxide-based heating brick.

Further, in the preparation process, the curing, curing and trimming of the heating insulation board are also included. The concrete operation of solidification is: and taking out the cured heating insulation board from the mold cavity, wherein the curing time is 8-30 minutes. The specific operation of curing is as follows: curing the heating insulation board for 2 days after curing. And trimming after curing.

Further, in order to improve the adhesive force between the tile layer and the porous niobium carbide MXene/reduced graphene oxide-based heating film, the bonded porous niobium carbide MXene/reduced graphene oxide-based heating brick is subjected to pressure maintaining reinforcement for 3 days.

As shown in fig. 2 to 3, the present invention is a porous niobium carbide MXene/reduced graphene oxide based heat generating film 02 according to an embodiment of the present invention. The porous niobium carbide MXene/reduced graphene oxide-based heating film 02 sequentially comprises a first transparent insulating layer 1, a porous niobium carbide MXene/reduced graphene oxide-based conductive film 2, an electrode 3 and a second transparent insulating layer 4 from top to bottom. The first transparent insulating layer 1 covers the upper surface of the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2, and the second transparent insulating layer 4 covers the lower surface of the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2, so that the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2 is isolated in a closed insulating space, and electric leakage is prevented when the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2 generates heat when electricity is conducted. One end of the electrode 3 is electrically connected with the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2, specifically, the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2 is pressed against the electrode 3 or is electrically connected with the electrode 3 through a conductive bonding pad. The other end of the electrode 3 extends out of the first transparent insulating layer 1 (or extends out of the second transparent insulating layer 4, and also has a waterproof function), that is, the electrode 3 extends to the outside from the inside of the insulating space between the first transparent insulating layer 1 and the second transparent insulating layer 4, so that the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2 is electrically conducted with an external power supply.

Further, the material of the first transparent insulating layer 1 and the second transparent insulating layer 4 may be PET or PI.

Further, a non-layered molybdenum nanosheet/graphene-based fiber film 6 is further arranged between the second transparent insulating layer 4 and the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2, and the non-layered molybdenum nanosheet/graphene-based fiber film 6 is abutted to the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2 to play a role in a heat conducting layer and a conducting layer. The non-layered molybdenum nano sheet/graphene-based fiber film 6 has extremely high thermal conductivity, and the non-layered molybdenum nano sheet/graphene-based fiber film 6 is arranged in a fibrous shape, so that the surface area is extremely large, infrared rays can be rapidly radiated outwards to realize heat dissipation, and the local temperature of the porous niobium carbide MXene/reduced graphene-oxide-based conductive film 2 is prevented from being too high due to insufficient heat dissipation. The non-layered molybdenum nano sheet/graphene-based fiber film 6 has conductivity and can also serve as an electrode of the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2.

Further, a waterproof adhesive layer 5 is further arranged between the first transparent insulating layer 1 and the second transparent insulating layer 4, and the waterproof adhesive layer 5 is respectively adhered to the first transparent insulating layer 1 and the second transparent insulating layer 4 to form a closed cavity. The porous niobium carbide MXene/reduced graphene oxide-based conductive film 2 and the non-layered molybdenum nanosheet/graphene-based fiber film 6 are arranged in the closed cavity, and the electrode 3 extends out of the closed cavity from the inside of the closed cavity.

Further, the electrode 3 includes a transverse arm and a vertical arm that are connected to each other vertically, the transverse arm extends out of the closed cavity from the non-layered molybdenum nanosheet/graphene-based fiber film 6 in a transverse direction (specifically, the transverse arm is transversely inserted into the non-layered molybdenum nanosheet/graphene-based fiber film 6), and the vertical arm extends out of the non-layered molybdenum nanosheet/graphene-based fiber film 6 in a longitudinal direction and is electrically connected to the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2 (also, the longitudinal arm is longitudinally inserted into the non-layered molybdenum nanosheet/graphene-based fiber film 6). In other embodiments, the electrode 3 may have other structures, and only the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2 is ensured to be electrically connected with the outside through the electrode 3.

Further, the solar cell further comprises a heat reflecting layer 7, wherein the heat reflecting layer 7 is arranged in a concave shape (a cap shape), and a containing groove is formed below the heat reflecting layer 7. In the porous niobium carbide MXene/reduced graphene oxide-based heating film, the upper end of the non-layered molybdenum nanosheet/graphene-based fiber film 6 is embedded into the accommodating groove, the non-layered molybdenum nanosheet/graphene-based fiber film 6 and the accommodating groove surround a cavity (which can be a sealed cavity or a non-sealed cavity), the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2 is arranged in the cavity, on one hand, the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2 is fixed, on the other hand, the infrared radiation direction of the porous niobium carbide MXene/reduced graphene oxide-based heating film is restrained by means of the heat reflection layer 7, and the heat utilization rate is improved. In a specific embodiment, the first transparent insulation layer 1 is installed adjacent to the insulation layer 03 and the second transparent insulation layer 4 is installed adjacent to the tile layer 01, thereby ensuring that the heat radiation direction is radiated toward the indoor space on the ground.

Further, the porous niobium carbide MXene/reduced graphene oxide-based conductive film 2 comprises three porous niobium carbide MXene/reduced graphene oxide-based conductive film monomers arranged side by side, and correspondingly, the non-layered molybdenum nanosheet/graphene-based fiber film 6 comprises three non-layered molybdenum nanosheet/graphene-based fiber film monomers arranged side by side. A non-layered molybdenum nanosheet/graphene-based fiber film monomer 6 is arranged between each porous niobium carbide MXene/reduced graphene oxide-based conductive film monomer and the second transparent insulating layer 4.

Furthermore, two ends of each of the three porous niobium carbide MXene/reduced graphene oxide-based conductive film monomers are respectively provided with a square hole which is uniformly distributed.

The following describes in detail the preparation method of the non-layered molybdenum nanosheet/graphene-based fibrous membrane and the prepared non-layered molybdenum nanosheet/graphene-based fibrous membrane by using specific examples.

Preferably, the preparation of the non-layered molybdenum nanosheet/graphene-based fibrous membrane comprises the following steps:

preparing a pre-stripping dispersion of molybdenum powder: molybdenum powder was provided and added to isopropanol to prepare an isopropanol dispersion of molybdenum powder at a concentration of 200 mg/ml. Performing 400W ultrasound on the isopropanol dispersion liquid added with the molybdenum powder at the temperature of 10 ℃ for 48 h, and centrifuging the isopropanol dispersion liquid of the molybdenum powder to collect supernatant after the ultrasound is finished, wherein the centrifugation speed is 2200 rpm, the centrifugation time is 20 h, and the obtained supernatant is the pre-stripping dispersion liquid of the molybdenum powder.

Preparing a mixture of molybdenum powder and graphene oxide: adding graphene oxide into the prepared pre-stripping dispersion liquid of the molybdenum powder, wherein the mass ratio of the graphene oxide to the molybdenum powder in the supernatant is 3:1, transferring the pre-stripping dispersion liquid of the graphene oxide and the molybdenum powder into a 10 ℃ water bath kettle to perform secondary water bath ultrasound, wherein the power of the secondary water bath ultrasound is 400W, and the time of the secondary water bath ultrasound is 16 h. And after the secondary water bath ultrasound is finished, centrifuging the pre-stripping dispersion liquid of the molybdenum powder added with the graphene oxide at 11000 rpm for 50 min, and collecting a bottom layer mixture. And dispersing the bottom layer mixture in water, shaking and washing the bottom layer mixture, and freeze-drying the washed mixture to obtain a mixture of molybdenum powder and graphene oxide.

Preparing a non-layered molybdenum nanosheet/graphene oxide dispersion liquid: and dispersing the mixture of molybdenum powder and graphene oxide in N-methyl pyrrolidone to prepare a mixed solution, wherein the concentration of the mixture of molybdenum powder and graphene oxide is 5 mg/ml. Performing ultrasonic treatment on an N-methylpyrrolidone solution of a mixture of molybdenum powder and graphene oxide by using pulse probe ultrasonic treatment, wherein the frequency of the pulse probe ultrasonic treatment is set as follows: the ultrasonic treatment is carried out for 5 s at an interval of 5 s, the temperature of the pulse probe ultrasonic treatment is 10 ℃, the power of the pulse probe ultrasonic treatment is 250W, and the time of the pulse probe ultrasonic treatment is 8 h. And after the pulse probe finishes the ultrasonic treatment, concentrating the mixed solution by a vacuum rotary evaporation method, wherein the solid content concentration of the concentrated mixed solution is 25 mg/ml. And concentrating to obtain the non-layered molybdenum nanosheet/graphene oxide dispersion liquid.

Spinning: adding PI powder into the non-layered molybdenum nanosheet/graphene oxide dispersion liquid, transferring the mixture into an oil bath pan at 105 ℃, uniformly stirring the mixture, and performing electrostatic spinning by taking the mixture as spinning solution, wherein the mass fraction of the PI powder is 9%. And (3) collecting and preparing the non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane by using a spinning needle with the inner diameter increased along the filament outlet direction, wherein the inner diameter of the thin end of the spinning needle is 0.3 mm, the inner diameter of the thick end of the spinning needle is 0.36 mm, the receiving distance is 20 cm, and the electrostatic spinning voltage is 30 KV.

And (3) post-treatment: and (3) washing the non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane with deionized water for three times, vacuum-drying at 70 ℃ for 8 h, and repeating the washing and drying processes once. And (3) soaking the washed non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane in hydrazine hydrate for reduction for 2 h. And repeating the washing and drying processes once again after reduction to obtain the non-layered molybdenum nanosheet/graphene-based fiber membrane.

The following describes in detail the preparation method of the porous niobium carbide MXene/reduced graphene oxide-based heating film and the prepared porous niobium carbide MXene/reduced graphene oxide-based heating film by examples. The preparation method of the porous niobium carbide MXene/reduced graphene oxide-based heating film comprises the following steps.

Preparing a working electrode: graphite powder and niobium-containing aluminum carbide powder (Nb in examples 1, 3, 5 and 7) were provided₃AlC₂Nb in examples 2, 4, 6 and 8₄AlC₃Powder), grinding graphite powder and niobium-aluminum carbide powder and uniformly mixing, and pressing the ground graphite powder and niobium-aluminum carbide powder into a cylindrical working electrode. The amount of graphite powder, niobium-aluminum carbide powder, and fineness of grinding (mesh number of sieve) in each example are shown in table 1.

TABLE 1 amount of graphite powder and niobium-aluminum carbide powder used and grinding fineness

Preparing a niobium carbide/graphite oxide material: fixing the working electrode prepared in the previous step as a positive electrode in an electrolytic cell, adding an electrolyte into the electrolytic cell to immerse the working electrode in the electrolyte, and specifically: the upper end of the working electrode is connected with a lead, and the lower part of the working electrode is immersed in electrolyte (the lead is ensured not to be in contact with the electrolyte, and the lead is prevented from ionizing to generate impurity substances). The working electrode is electrified to be electrolyzed, the electrolytic cell is cooled through cooling equipment in the electrolysis process, and the electrolyte is stirred through a stirring device, such as a magnetic stirrer. The electrolyte is an organic solvent containing fluorine anions, and an etchant is generated in the electrolysis process of the fluorine anions, specifically, the type of the fluorine anions, the type of the organic solvent (two or more organic solvents are mixed organic solvents, and equal amount combination is adopted in the embodiment), the concentration of the fluorine anion-containing liquid, the voltage, the electrolysis time and the temperature maintained by the electrolyte are shown in table 2. After the electrolysis, the electrolyte is sieved by a 400-mesh sieve and then centrifuged to collect precipitates, and the centrifugal rotating speed and time are shown in table 2.

TABLE 2 parameters in the preparation of niobium carbide/graphite oxide materials

Preparing a niobium carbide MXene/reduced graphene oxide dispersion liquid: and dissolving the niobium carbide/graphite oxide material precipitate prepared in the previous step into isopropanol to prepare isopropanol containing the niobium carbide/graphite oxide material, wherein the mass-volume ratio of the niobium carbide/graphite oxide material to the isopropanol is shown in table 3. The isopropyl alcohol containing the niobium carbide/graphite oxide material was subjected to probe ultrasound, and the power of the probe ultrasound (referred to as "probe ultrasound power"), the time (referred to as "probe ultrasound time"), the frequency, and the temperature maintained during the ultrasound process (referred to as "probe ultrasound temperature", which refers to the temperature set for the constant temperature water bath) are shown in table 3. After the probe ultrasound is finished, primarily centrifuging isopropanol containing niobium carbide/graphite oxide materials at 8000-15000 rpm for 10-30 min, and collecting primary precipitates. The rotation speed and time of the primary centrifugation are shown in Table 3.

TABLE 3 parameters of the Probe ultrasonic and Primary centrifugation Process

And adding the collected primary precipitate into a reducing reagent for reduction, and uniformly stirring and mixing the reducing reagent to ensure that the primary precipitate is fully dispersed in the reducing reagent. Wherein the kind of the reducing agent, the concentration of the reducing agent, the ratio of the primary precipitate to the mass volume of the reducing agent (referred to as "mass volume ratio"), and the reduction time are shown in Table 4. And after the reduction is finished, centrifuging the reducing reagent again, collecting the reduced precipitate, and drying. The re-centrifugation rotation speed and re-centrifugation time are shown in table 4. The drying is completed by a freezing vacuum drying device. After drying, dispersing the dried precipitate in a first dispersing agent (wherein, the mixture of the two dispersing agents in any proportion is adopted in the embodiment, and equal amount combination is adopted), and performing water bath ultrasound to obtain the niobium carbide MXene/reduced graphene oxide dispersion liquid. Wherein, the species of the first dispersant, the ultrasonic power of the water bath, the ultrasonic time of the water bath, the ultrasonic temperature of the water bath, and the like are shown in table 4.

TABLE 4 reductive reagent and parameters of the Water bath sonication Process

Preparing granular resin slurry: a particulate powder and a second dispersant are provided and mixed, wherein the type of particulate powder, the diameter of the particulate powder, the type of second dispersant, and the ratio of the particulate powder to the second dispersant by mass to volume (referred to as "mass to volume ratio") are shown in table 5. Resin was added to the second dispersion while stirring the second dispersion to produce a resin slurry of the particles, wherein the resin type (mixture of resins including a mixture of resins in any ratio, in the example, in equal combination) and the resin concentration are shown in Table 5.

TABLE 5 parameters in the step of preparing a resin slurry of particulate matter

Preparing niobium carbide MXene/reduced graphene oxide-based conductive ink: 500 mg of the particulate resin slurry, the niobium carbide MXene/reduced graphene oxide dispersion liquid, the polyacrylonitrile-maleic anhydride copolymer and the stabilizer are mixed, wherein the mass of the niobium carbide MXene/reduced graphene oxide dispersion liquid, the mass of the polyacrylonitrile-maleic anhydride copolymer and the mass of the stabilizer (containing multiple stabilizers, the multiple stabilizers are combined in any proportion, and the same amount of stabilizer is combined in the embodiment) and the type of the stabilizer are shown in Table 6. After mixing, the mixture was transferred to a protective gas atmosphere and then stirred in a constant temperature water bath until the volume was concentrated, and the specific protective gas type, water bath temperature and concentration factor (volume of the concentrated liquid compared with the original liquid volume) are shown in table 6. After concentration, the mixed solution has proper film forming property and leveling property, and the porous niobium carbide MXene/reduced graphene oxide-based conductive ink is prepared.

TABLE 6 parameters in the preparation of niobium carbide MXene/reduced graphene oxide inks

Preparing a porous niobium carbide MXene/reduced graphene oxide-based heating film: and (2) taking the non-layered molybdenum nanosheet/graphene-based fiber film, printing the porous niobium carbide MXene/reduced graphene oxide-based conductive ink on the non-layered molybdenum nanosheet/graphene-based fiber film in a printing mode, curing to form a film, immersing the whole film into a dilute hydrochloric acid solution, soaking for 2 hours, washing and drying to obtain the porous niobium carbide MXene/reduced graphene oxide-based conductive film. And (3) thermally compounding the porous niobium carbide MXene/reduced graphene oxide-based conductive film with an electrode to obtain a PET insulating layer, thus obtaining the porous niobium carbide MXene/reduced graphene oxide-based heating film.

Effects of the embodiment

(1) Service life test

The porous niobium carbide MXene/reduced graphene oxide-based heating films prepared in examples 1 to 8 were subjected to an initial sheet resistance test by cutting the heating film with a blade having a length and a width of 10 cm. And inserting electrodes at two ends of the non-layered molybdenum nanosheet/graphene-based fiber membrane for electrifying and generating heat, and simultaneously carrying out a service life test. The test method is as follows: the porous niobium carbide MXene/reduced graphene oxide-based heating film corresponding to each example was continuously electrified to generate heat, and the sheet resistance value results of the heating film measured every other week (W) are shown in Table 7.

TABLE 7 service life test results

From the results in table 7, it can be seen that the porous heating films corresponding to examples 1-8 have small changes in the overall sheet resistance after being continuously electrified for 5W heat generation, which indicates that the porous niobium carbide MXene/reduced graphene oxide-based heating film of the present invention has stable structure, composition, and electrical conductivity, and can meet the heat generation requirement of electrical heating equipment for long-time heating.

(2) Antibacterial testing

The porous niobium carbide MXene/reduced graphene oxide-based heating film prepared in the examples 1 to 8 is cut into a heating film with the length, the width and the thickness of 20 cm and about 1 mm by a blade, and electrodes are inserted at two ends of the non-layered molybdenum nanosheet/graphene-based fiber film for electrifying, generating heat and carrying out an antibacterial test. The test method is as follows: the culture solution (rejuvenated) of model strains (escherichia coli, candida albicans, salmonella typhimurium, staphylococcus aureus) was spotted by means of an inoculating needle onto petri dishes (containing conventional solid medium for bacterial culture), each petri dish was inoculated with a single strain 10 times and each strain 200 times (divided into 20 dishes). After inoculation, all the culture dishes are divided into two groups and respectively placed in two culture chambers for simulating living environment. One of them is the laboratory group culture room, is provided with a plurality of aforementioned heating film and circular telegram heat production in the laboratory group culture room, and the culture dish is 5~ 30 cm apart from the fibrous membrane, and the laboratory group culture room is by the heating film heat production energy supply, and the temperature control in the culture room is about 37 ℃, and another culture room is the control group culture room, and the temperature that sets up the control group culture room equally is 37 ℃, is supplied heat by the air conditioner, and statistics laboratory group bacterial colony growth condition after 12 h all cultivateed in laboratory group culture room and control group culture room. The average colony size (diameter of colony) of each bacterial colony in the control group is calculated, the average colony size is used as a reference value, the colony with the diameter less than or equal to half of the reference value in the experimental group is marked as bacteriostasis, the colony which does not grow at the point of sample application is marked as sterilization, and the colony with the diameter more than or equal to half of the reference value is marked as normal growth. The results of the statistical percentages are shown in Table 8.

TABLE 8 antimicrobial test results

As is clear from the results in Table 8, the sterilization rates of the exothermic films of examples 1 to 8 against Escherichia coli, Candida albicans and Salmonella typhimurium were all over 99%, and the sterilization rates against Staphylococcus aureus were all over 93%. After being doped with each other, the niobium carbide MXene and the reduced graphene oxide can be promoted to be in direct contact with and doped with the reduced graphene oxide, so that the mutual stacking or local aggregation of the niobium carbide MXene or the reduced graphene oxide is prevented, a single two-dimensional material is promoted to be stripped into few layers of nanosheets, and the nanosheets are mixed with dispersed graphite powder to form a conductive network structure with stable niobium carbide MXene-reduced graphene oxide-graphite particles. After the heating films corresponding to embodiments 1-8 are electrified, the surface area can be increased by virtue of a large number of gap structures on the surfaces of the heating films, which is helpful for releasing a large number of infrared rays and has a sterilization effect. In addition, by means of carrier transmission between the niobium carbide MXene and the graphene sheet layer, a small amount of active oxygen free radicals can be generated at a heterojunction between the niobium carbide MXene and the graphene sheet layer, and the effects of assisting sterilization and cleaning the surface are achieved.

(3) Infrared wavelength and normal emissivity testing

The heating films corresponding to the embodiments 1 to 8 were taken and tested for infrared wavelength range and normal emissivity according to the national standard GB/T7287-. The calculation data show that the heating film corresponding to the embodiment 1-8 can release 3-20 micrometers of far infrared rays, the proportion of the far infrared rays with the wave band of 4-16 micrometers is over 90%, the normal emissivity is over 88%, and the electrothermal conversion rate is over 99%, so that the heating film can be widely applied to the fields of floor heating, physiotherapy, clothes and the like. The niobium carbide MXene and the reduced graphene oxide are doped with each other, so that the uniform distribution of the conductor is increased, the resistance value of the heating film is reduced, the uniformity of the heating film is improved, and the like.

(4) Stability and leakage safety testing

The heating films corresponding to the embodiments 1 to 8 are cut into heating films with the length, the width and the thickness of 20 cm and the thickness of about 1 mm by a blade, electrodes are inserted on the fiber films at the two ends of the heating films, electricity is conducted to generate heat, and the uniformity of heating temperature is assessed by an infrared imaging instrument. Any two heating temperature differences of each heating film are less than or equal to 5 ℃ and more than 2.5 ℃, the heating film is qualified, the heating film is excellent when the heating temperature difference is less than or equal to 2.5 ℃, the heating film is unqualified when the heating temperature difference is more than 5 ℃, and the statistical result is shown in table 9.

The heating film for the heat production uniformity test is continuously electrified to produce heat for the heat production stability test. The statistical method, the heat production is carried out for 90000 hours by continuous electrification, and compared with the beginning of the heat production, the disqualification is marked when the heat production power is reduced by more than 2.5 percent after the 90000 hours of the heat production; the heat production power is reduced by less than or equal to 2.5 percent and is greater than 1 percent, and the product is marked as qualified; the decrease of heat generation power less than or equal to 1% is marked as excellent, and the statistical results are shown in Table 9.

After 90000 hours of electricity and heat generation, the electricity and the heat generation are continued for a leakage safety test. The specific test method was measured with reference to GB/T12113 (idt IEC 60990). The leakage current is less than or equal to 0.05 mA and greater than 0.02 mA and is marked as qualified; the leakage current is less than 0.02 mA and is marked as excellent; the leakage current is greater than 0.05 mA and is marked as unqualified. The results of the measurements are shown in Table 9.

TABLE 9 stability and leakage safety test data

As can be seen from the results in table 9, the heat-generating films of examples 1 to 8 all showed excellent test results in the temperature uniformity test, the heat-generating stability test, and the leakage safety test, indicating that the heat-generating films of examples 1 to 8 of the present invention have excellent heat-generating uniformity, heat-generating stability, and leakage safety.

(5) Heat resistance and tensile Property test

The porous niobium carbide MXene/reduced graphene oxide-based heating film prepared in the examples 1 to 8 was cut by a blade to form a heating film with a width of 20 cm and a thickness of about 1 mm, and a thermal deformation temperature test was performed according to GB/T1634-. The test results are shown in Table 10.

The prepared porous niobium carbide MXene/reduced graphene oxide-based heating film is subjected to tensile resistance test on a universal tester (the test standard is GB/T1040-.

TABLE 10 Heat resistance test results

The results in Table 10 show that the thermal deformation temperatures of the porous niobium carbide MXene/reduced graphene oxide-based heating films prepared in examples 1-8 exceed 100 ℃, and the fiber films can meet the heat production requirements of low-temperature and medium-temperature heat production equipment. The results in Table 10 show that the tensile strength of the porous niobium carbide MXene/reduced graphene oxide-based heating films prepared in examples 1-8 exceeds 34 MPa, and the films can meet the requirements of flexibility, wear resistance and tensile resistance of common heat-generating equipment.

(6) Ambient temperature test

The porous niobium carbide MXene/reduced graphene oxide-based heating film prepared in example 4 is used for preparing a porous niobium carbide MXene/reduced graphene oxide-based warm brick, and the porous niobium carbide MXene/reduced graphene oxide-based warm brick is used for testing the ambient temperature after heat production. The test method is as follows: ambient temperature is 20 ℃, and the temperature of setting up the brick with ground through the temperature setting button after the circular telegram is 60 ℃ and continuous heat production 10min, through the temperature of infrared temperature detector detection brick with ground, the temperature of 1 meter department above the brick with ground and the temperature of 2 meters departments above the brick with ground, the result shows: the temperature of the floor heating brick is 60 ℃, the temperature of the place 1 meter above the floor heating brick is 48 ℃, and the temperature of the place 2 meter above the floor heating brick is 44 ℃.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The porous niobium carbide MXene/reduced graphene oxide base heating brick is characterized by comprising an insulating layer, a porous niobium carbide MXene/reduced graphene oxide base heating film and a ceramic tile layer, wherein the porous niobium carbide MXene/reduced graphene oxide base heating film is clamped between the insulating layer and the ceramic tile layer;

2. The porous niobium carbide MXene/reduced graphene oxide based warm brick according to claim 1, wherein the heat insulating layer is made of polyurethane;

in the process of preparing the porous niobium carbide MXene/reduced graphene oxide base warm brick, the porous niobium carbide MXene/reduced graphene oxide base heating film is placed in an upper die cavity, a polyurethane base material is placed in a lower die cavity, the upper die cavity and the lower die cavity are buckled while the polyurethane base material is heated and foamed, a heating and insulating layer formed by integrally forming the porous niobium carbide MXene/reduced graphene oxide base heating film and the insulating layer is prepared, and finally the ceramic brick layer is bonded with the porous niobium carbide MXene/reduced graphene oxide base heating film to prepare the porous niobium carbide MXene/reduced graphene oxide base warm brick.

3. The porous niobium carbide MXene/reduced graphene oxide based warm brick as claimed in claim 1, characterized in that, in the step of preparing the niobium carbide/graphite oxide material, the fluorine-containing anion liquid includes at least one of 1-ethyl-3-methylimidazole tetrafluoroborate, 1-ethyl-3-methylimidazole hexafluorophosphate, 1-butyl-3-methylimidazole tetrafluoroborate, 1-butyl-3-methylimidazole hexafluorophosphate, 1-octyl-3-methylimidazole tetrafluoroborate, 1-octyl-3-methylimidazole hexafluorophosphate, 1-hexyl-3-methylimidazole tetrafluoroborate and 1-hexyl-3-methylimidazole hexafluorophosphate.

4. The porous niobium carbide MXene/reduced graphene oxide-based heating brick as claimed in claim 1, wherein a non-layered molybdenum nanosheet/graphene-based fiber film is further disposed between the second transparent insulating layer and the porous niobium carbide MXene/reduced graphene oxide-based conductive thin film, and the preparation method of the non-layered molybdenum nanosheet/graphene-based fiber film comprises the following steps:

5. The porous niobium carbide MXene/reduced graphene oxide based warm brick according to claim 4, wherein a waterproof adhesive layer is further disposed between the first transparent insulating layer and the second transparent insulating layer, and the waterproof adhesive layer is respectively adhered to the first transparent insulating layer and the second transparent insulating layer to form a closed cavity;

the porous niobium carbide MXene/reduced graphene oxide-based conductive film and the non-layered molybdenum nanosheet/graphene-based fiber film are arranged in the closed cavity, and the electrode extends out of the closed cavity.

6. The porous niobium carbide MXene/reduced graphene oxide based warm brick of claim 5, wherein the electrode comprises interconnected lateral arms extending from the non-layered molybdenum nanoplatelet/graphene-based fiber membrane out of the closed cavity and vertical arms extending from the non-layered molybdenum nanoplatelet/graphene-based fiber membrane and electrically connected to the porous niobium carbide MXene/reduced graphene oxide-based conductive thin film.

7. The porous niobium carbide MXene/graphene oxide-based heating brick according to claim 6, wherein a heat reflecting layer is further disposed between the first transparent insulating layer and the porous niobium carbide MXene/graphene oxide-based conductive film, and the heat reflecting layer is disposed in a concave shape to form a receiving groove;

one surface of the non-layered molybdenum nanosheet/graphene-based fiber membrane is embedded into the accommodating groove, the non-layered molybdenum nanosheet/graphene-based fiber membrane and the accommodating groove enclose a cavity, and the porous niobium carbide MXene/reduced graphene oxide-based conductive film is arranged in the cavity.

8. The porous niobium carbide MXene/reduced graphene oxide based heating brick according to claim 7, wherein the porous niobium carbide MXene/reduced graphene oxide based conductive thin film comprises a plurality of porous niobium carbide MXene/reduced graphene oxide based conductive thin film monomers arranged side by side, and correspondingly, the non-layered molybdenum nano sheet/graphene based fiber film comprises a plurality of non-layered molybdenum nano sheet/graphene based fiber film monomers arranged side by side;

a non-layered molybdenum nanosheet/graphene-based fiber membrane monomer is arranged between any porous niobium carbide MXene/reduced graphene oxide-based conductive membrane monomer and the second transparent insulating layer.

9. The porous niobium carbide MXene/reduced graphene oxide based warm brick according to claim 4, wherein in the step of preparing the non-layered molybdenum nanosheet/graphene oxide dispersion, the mass-to-volume ratio of the mixture of molybdenum powder and graphene oxide to N-methyl pyrrolidone is 5 mg/ml, the pulse probe ultrasound time is 8 h, the pulse probe ultrasound power is 250W, and the pulse probe ultrasound frequency is set as follows: ultrasound 5 s, interval 5 s.

10. The porous niobium carbide MXene/reduced graphene oxide based warm brick according to claim 4, wherein in the post-treatment step, the non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane is washed with deionized water 3 times, and the non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane is transferred to a vacuum drying oven at 70 ℃ for drying for 8 hours;

soaking the dried non-layered molybdenum nanosheet/graphene oxide hybrid porous fiber membrane in HI and NaBH₄And hydrazine hydrate and ascorbic acid are reduced to prepare the non-layered molybdenum nanosheet/graphene-based fiber membrane.