CN115938818A - Preparation method and application of flexible nitrogen-doped titanium carbide MXene thin-film electrode with high volume-to-volume ratio capacitance - Google Patents

Preparation method and application of flexible nitrogen-doped titanium carbide MXene thin-film electrode with high volume-to-volume ratio capacitance Download PDF

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CN115938818A
CN115938818A CN202211470770.3A CN202211470770A CN115938818A CN 115938818 A CN115938818 A CN 115938818A CN 202211470770 A CN202211470770 A CN 202211470770A CN 115938818 A CN115938818 A CN 115938818A
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罗洋洋
李喜飞
贾舒婷
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Xian University of Technology
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Abstract

The invention discloses a preparation method of a flexible nitrogen-doped titanium carbide MXene thin-film electrode with high volume-to-volume ratio capacitance, which comprises the steps of firstly carrying out Ti treatment on Ti 3 AlC 2 The Al layer in the alloy is selectively etched to obtain single-layer or few-layer Ti 3 C 2 Adding the nanosheet colloidal solution into absolute ethyl alcohol, and centrifuging to obtain Ti 3 C 2 Precipitating; adding it into ethanol solution containing urea; transferring the mixed solution into a polytetrafluoroethylene lining for sealing, and reacting in a forced air drying oven to obtain nitrogen-doped Ti 3 C 2 Precipitation, i.e. N-Ti 3 C 2 Adding deionized water into the precipitate, and performing ultrasonic treatment to obtain N-Ti 3 C 2 Vacuum filtering the colloidal solution, and naturally air drying to obtain the flexible self-supporting nitrogen-doped Ti 3 C 2 A film; the invention has simple synthesis process and easy operation, and the prepared flexible self-supporting nitrogen-doped Ti is 3 C 2 The film electrode has ultrahigh volume specific capacitance, can be used for flexible and miniature super capacitors, and has good application prospect in the field of energy storage.

Description

Preparation method and application of flexible nitrogen-doped titanium carbide MXene thin-film electrode with high volume-to-volume ratio capacitance
Technical Field
The invention belongs to the technical field of thin film electrode materials, and relates to a flexible nitrogen-doped titanium carbide MXene thin film electrode with high volume ratio capacitance.
The invention also relates to a preparation method of the flexible nitrogen-doped titanium carbide MXene thin-film electrode with high volume-specific capacitance;
the invention also relates to application of the flexible nitrogen-doped titanium MXene thin-film electrode with high volume-specific capacitance in a flexible supercapacitor.
Background
With the continuous development of global economy and society, people increasingly expand the requirements on novel energy storage devices with high power, long service life, large capacity and environmental protection. The super capacitor is an energy storage device between a traditional capacitor and a storage battery, and has the advantages of high power density, high charging and discharging speed, long cycle service life, wide working temperature range and the like. The electrode material is a core component of the super capacitor and plays an important role in the energy storage property of the super capacitor; therefore, the preparation of the low-cost and high-performance electrode material has remarkable significance for the application of the super capacitor;
two-dimensional layered transition metal carbide, nitride or carbonitride (MXenes) has good surface hydrophilicity and mechanical strength, high specific surface area and electrical conductivity, and has caused extensive research hot tide in the aspects of energy storage, catalysis, sensors and the like in recent years; in particular Ti 3 C 2 As one of the most widely studied materials in the two-dimensional MXenes family of materials, the material shows excellent energy storage characteristics in the aspect of supercapacitor application; to accelerate Ti 3 C 2 Application in flexible and miniature super capacitor to improve Ti 3 C 2 The volume specific capacitance of (2) is imminent;
due to Ti 3 C 2 Weak van der Waals acting force exists between the (MXene) layers, so that the nano sheets are easy to stack and re-overlap, and Ti is reduced 3 C 2 The surface utilization rate of the nano-sheet seriously influences the electrochemical performance of the nano-sheet as an electrode material. And heteroatom doping can introduce defect sites, regulate and control surface functional groups and chemical bonds of the defect sites, reduce Fermi level and further improve Ti 3 C 2 The conductivity of the nano-sheet is increased, more reactive active sites are added, and the re-stacking of the nano-sheet is effectively inhibited, so that the Ti content is improved 3 C 2 The specific capacitance and rate capability of (a) and the like are considered as effective performance improvement measures.
Disclosure of Invention
The invention aims to provide a flexible nitrogen-doped titanium carbide MXene thin-film electrode with high volume-to-volume ratio capacitance, and solves the problems of high cost, complex synthesis and poor electrochemical performance in the existing electrode material.
The invention also provides a preparation method of the flexible nitrogen-doped titanium MXene thin-film electrode with high volume-specific capacitance.
The third purpose of the invention is to provide the application of the flexible nitrogen-doped titanium carbide MXene thin film electrode with high volume ratio capacitance.
The first technical scheme adopted by the invention is that the preparation method of the flexible nitrogen-doped titanium MXene thin-film electrode with high volume-specific capacitance is implemented by the following steps:
step 1, adding deionized water and concentrated HCl into a polytetrafluoroethylene lining, and uniformly stirring to obtain an HCl aqueous solution; slowly adding LiF into the HCl aqueous solution, and uniformly stirring to obtain a mixed aqueous solution of HCl and LiF as an etching agent;
step 2, slowly adding Ti into the HCl and LiF mixed solution prepared in the step 1 3 AlC 2 Continuously stirring the powder in an oil bath kettle under constant temperature and magnetic force to etch off the Al layer;
step 3, repeatedly centrifuging and washing the etched suspension by using deionized water to obtain a plurality of layers of Ti 3 C 2 Precipitating;
step 4, in the multilayer Ti 3 C 2 Adding deionized water into the precipitate, introducing continuous argon flow, ultrasonically stripping, centrifuging to obtain supernatant as single layer or few layers of Ti 3 C 2 A nanosheet colloidal aqueous solution;
step 5, dissolving urea in absolute ethyl alcohol, and uniformly stirring;
step 6, measuring a certain volume of Ti 3 C 2 Adding the nanosheet colloid aqueous solution into ethanol, and centrifuging to obtain Ti 3 C 2 Precipitating;
step 7, subjecting the obtained Ti to 3 C 2 Adding the precipitate into the ethanol solution containing urea, and uniformly stirring;
step 8, transferring the mixed solution obtained in the step 7 into a polytetrafluoroethylene lining, sealing the polytetrafluoroethylene lining by using a stainless steel hydrothermal reaction kettle, carrying out solvothermal reaction in a forced air drying oven, cooling the reaction kettle to room temperature, and centrifugally washing the reaction kettle by using ethanol and deionized water to obtain nitrogen-doped Ti 3 C 2 Precipitating;
step 9, doping Ti in nitrogen 3 C 2 Adding deionized water into the precipitate, performing ultrasonic dispersion, vacuum filtration, and naturally air drying to obtain flexible self-supporting nitrogen-doped Ti 3 C 2 And a thin film electrode.
The invention is also characterized in that:
wherein the molar concentration of the HCl aqueous solution in the step 1 is 9mol/L, and the mass concentration of LiF is 0.1g/mL; the two times of stirring are 15 to 30min;
wherein the temperature of the oil bath in the step 2 is 35-45 ℃, the magnetic stirring time is 24-48 h, and the rotating speed of the magnetic stirring is 400-800 r/min; ti 3 AlC 2 The mass concentration of (A) is 0.05g/mL;
wherein the centrifugal time required by repeated centrifugal washing with deionized water in the step 3 is 2-5 min, the centrifugal rotating speed is 3500r/min, and the centrifugation is 1-2 times; centrifuging at 6000r/min for 2-3 times; centrifuging for 2-3 times at 9000 r/min; centrifugally washing until the pH value of the supernatant is not less than 6.0;
wherein in the step 4, the ultrasonic power is 90-100W, the ultrasonic time is 40-90min 3 C 2 The volume concentration of the nano-sheet colloid aqueous solution is 3.0-5.5 mg/mL; the centrifugal rotating speed is 1400-1600 r/min, and the centrifugal time is 20-40 min;
wherein the urea and Ti added in the step 5 3 C 2 The mass ratio of (A) to (B) is 0.5-4.0: 0.0485, and the stirring time is 20-40 min;
wherein in step 6 Ti 3 C 2 Colloidal aqueous solutionThe volume ratio of the ethanol to the ethanol is 1:1 to 3; the centrifugal speed is 6000 to 10000r/min, and the centrifugal time is 2 to 5min;
wherein the stirring time in the step 7 is 20-40 min;
wherein in the step 8, the filling ratio of the mixed solution in the polytetrafluoroethylene lining is 35-50%, the solvothermal reaction temperature is 200 ℃, and the reaction time is 24 hours; washing with ethanol and deionized water until the supernatant is neutral; the ultrasonic dispersion time in the step 9 is 10-30 min.
The second technical scheme adopted by the invention is that the flexible nitrogen-doped titanium MXene thin film electrode with high volume-specific capacitance prepared by the preparation method is doped with heteroatom nitrogen into Ti 3 C 2 Lattice of (2), nitrogen doped Ti 3 C 2 The interlayer spacing of the film is increased, and the nitrogen is doped with Ti 3 C 2 The film has flexible self-supporting characteristic and ultrahigh volume specific capacitance in acid electrolyte.
The third technical scheme adopted by the invention is that the high-volume-ratio-capacitance flexible nitrogen-doped titanium MXene thin-film electrode prepared by the preparation method is applied to a flexible supercapacitor.
The invention has the beneficial effects that:
the invention relates to a preparation method of a flexible nitrogen-doped titanium carbide MXene thin-film electrode with high volume-specific capacitance, which takes urea as a nitrogen source and adopts a one-step solvothermal method to prepare the flexible nitrogen-doped titanium MXene thin-film electrode on Ti 3 C 2 Introducing heteroatom nitrogen into the Ti alloy to prepare flexible self-supporting nitrogen-doped Ti 3 C 2 (N-Ti 3 C 2 ) A thin film electrode material; replacement of Ti by hetero atom nitrogen 3 C 2 C atoms in the crystal lattice and a part of the surface are adsorbed to generate abundant defect sites, so that the interlayer spacing is enlarged, and Ti is effectively prevented 3 C 2 The re-overlapping of the nano sheets provides more reactive active sites, improves the charge transmission speed and effectively improves the N-Ti 3 C 2 Specific capacitance and rate capability of the thin film electrode; the synthetic process is simple, the operation is easy, and the prepared flexible self-supporting nitrogen-doped Ti is 3 C 2 Electrochemical performance of the thin film electrodeLifting;
the nitrogen-doped Ti provided by the invention 3 C 2 Still maintains good two-dimensional sheet shape, and is doped with Ti 3 C 2 The nano-sheet colloid water solution is filtered in vacuum to form self-supporting N-Ti 3 C 2 The film has good flexibility, has ultrahigh volume specific capacitance in acid electrolyte, can be applied to flexible and miniature super capacitors, and achieves the aim of Ti 3 C 2 The electrochemical performance is improved, and the method has good application prospect.
Drawings
FIG. 1 is a schematic representation of nitrogen-doped Ti prepared in example 3 of the present invention 3 C 2 Optical photograph and SEM image of the thin film, wherein a is nitrogen-doped Ti 3 C 2 Planar optical picture of film, b picture is nitrogen doped Ti 3 C 2 Flexible self-supporting film, graph c is nitrogen doped Ti 3 C 2 Planar SEM image of film, d is nitrogen-doped Ti 3 C 2 Cross-sectional SEM images of the films.
FIG. 2 shows pure phase Ti of the present invention 3 C 2 Thin film and nitrogen-doped Ti prepared under different nitrogen doping amounts 3 C 2 XRD diffraction pattern of the film, wherein a-d are nitrogen-doped Ti prepared in examples 1-4 of the invention respectively 3 C 2 XRD diffraction pattern of the film;
FIG. 3 shows pure phase Ti of the present invention 3 C 2 Film and nitrogen-doped Ti prepared under different nitrogen doping amounts 3 C 2 XPS full spectrum of the film, wherein a-d are nitrogen-doped Ti prepared in examples 1-4 of the invention 3 C 2 XPS full spectrum of thin films;
FIG. 4 shows pure phase Ti of the present invention 3 C 2 Electrochemical performance of the thin film electrode, wherein a is pure phase Ti 3 C 2 Cyclic Voltammetry (CV) curves of the thin film electrode at different sweep rates, with the b diagram being pure phase Ti 3 C 2 Constant current charge and discharge (GCD) curves of the thin film electrode under different current densities;
FIG. 5 shows nitrogen-doped Ti prepared in example 3 of the present invention 3 C 2 Electrochemical performance of the thin film electrode, in the figure, a is the nitrogen-doped Ti prepared in example 3 3 C 2 Cyclic Voltammetry (CV) curves of the thin film electrode at different sweep rates, with the b plot being the nitrogen-doped Ti prepared in example 3 3 C 2 Constant current charging and discharging (GCD) curves of the film electrode under different current densities;
FIG. 6 shows pure phase Ti of the present invention 3 C 2 Film and nitrogen-doped Ti prepared under different nitrogen doping amounts 3 C 2 The volume ratio capacitance values of the thin film electrode under different sweep rates are shown in the figures, wherein a to d are respectively nitrogen-doped Ti prepared in the embodiments 1 to 4 of the present invention 3 C 2 The volume ratio capacitance value of the film electrode under different sweep speeds.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
Example 1
Flexible nitrogen-doped titanium carbide MXene thin-film electrode material with high volume-specific capacitance, wherein nitrogen atoms enter Ti 3 C 2 In the lattice, the interlayer spacing is enlarged, urea and Ti 3 C 2 Is 0.5:0.0485;
the preparation method of the flexible nitrogen-doped titanium carbide MXene thin film electrode with high volume-to-volume ratio capacitance comprises the following steps:
step 1, adding deionized water and concentrated HCl into a polytetrafluoroethylene lining, and stirring for 15min on a magnetic stirrer to obtain HCl aqueous solution with the molar concentration of 9 mol/L; slowly adding LiF into the 9mol/L HCl aqueous solution, stirring on a magnetic stirrer for 15min, wherein the mass concentration of LiF is 0.1g/mL, and obtaining a mixed aqueous solution of HCl and LiF as an etching agent;
step 2, slowly adding Ti into the HCl and LiF mixed solution 3 AlC 2 Powder of Ti 3 AlC 2 The mass concentration of the Al layer is 0.05g/mL, continuous constant-temperature magnetic stirring is carried out in an oil bath pot, the oil bath temperature is 35 ℃, the magnetic stirring time is 24 hours, the magnetic stirring rotating speed is 400r/min, and the Al layer is etched away;
step 3, repeatedly centrifugally washing the etched suspension by using deionized water, and separatingThe core time is 2min, the centrifugal rotation speed is 3500r/min (centrifuging for 2 times), 6000r/min (centrifuging for 3 times), 9000r/min (centrifuging for 3 times), when the pH value of the supernatant is more than 6.0, multilayer Ti is obtained 3 C 2 Precipitating;
step 4, in the multilayer Ti 3 C 2 Adding deionized water into the precipitate, introducing continuous argon flow, performing ultrasonic treatment in 100W ultrasonic machine for 1 hr, centrifuging at 1500r/min for 30min to obtain supernatant as single layer or few layers of Ti 3 C 2 The volume concentration of the nano-sheet colloid aqueous solution is 4.85mg/mL;
step 5, dissolving 0.5g of urea in 20mL of absolute ethyl alcohol, and stirring for 30min on a magnetic stirrer;
step 6, measuring 10mL of Ti 3 C 2 Aqueous nanosheet colloid solution, adding it to ethanol, ti 3 C 2 The volume ratio of the colloidal aqueous solution to the ethanol is 1:1, centrifuging at 9000r/min for 2min to obtain Ti 3 C 2 Precipitating;
step 7, subjecting the obtained Ti to 3 C 2 Adding the precipitate into the ethanol solution containing urea, and stirring for 30min on a magnetic stirrer;
and step 8: transferring the obtained mixed solution into a polytetrafluoroethylene lining with the filling ratio of 40%, sealing the mixed solution by using a stainless steel hydrothermal reaction kettle, carrying out solvothermal reaction in a forced air drying oven at the reaction temperature of 200 ℃ for 24 hours, cooling the reaction kettle to room temperature, carrying out centrifugal washing by using ethanol and deionized water until the supernatant is neutral, and obtaining the nitrogen-doped Ti 3 C 2 Precipitating;
and step 9: doping of Ti in nitrogen 3 C 2 Adding deionized water into the precipitate, ultrasonically dispersing for 20min, vacuum filtering, and naturally air drying to obtain flexible self-supporting nitrogen-doped Ti 3 C 2 (N-Ti 3 C 2 ) And a thin film electrode.
Example 2
The flexible nitrogen-doped titanium MXene thin film electrode material with high volume-specific capacitance has nitrogen atoms entering Ti 3 C 2 In the lattice, the interlayer spacing is enlarged, urea and Ti 3 C 2 The mass ratio of (A) to (B) is 1.5:0.0485.
the preparation method of the flexible nitrogen-doped titanium carbide MXene thin film electrode with high volume-to-volume ratio capacitance comprises the following steps:
step 1, adding deionized water and concentrated HCl into a polytetrafluoroethylene lining, and stirring for 30min on a magnetic stirrer to obtain HCl aqueous solution with the molar concentration of 9 mol/L; slowly adding LiF into the 9mol/L HCl aqueous solution, stirring on a magnetic stirrer for 15min, wherein the mass concentration of LiF is 0.1g/mL, and obtaining a mixed aqueous solution of HCl and LiF as an etching agent;
step 2, slowly adding Ti into the HCl and LiF mixed solution 3 AlC 2 Powder of Ti 3 AlC 2 The mass concentration of the Al layer is 0.05g/mL, continuous constant-temperature magnetic stirring is carried out in an oil bath pot, the oil bath temperature is 45 ℃, the magnetic stirring time is 48 hours, the magnetic stirring rotating speed is 800r/min, and the Al layer is etched away;
step 3, repeatedly centrifuging and washing the etched suspension by using deionized water for 2min, wherein the centrifuging speeds are 3500r/min (centrifuging for 1 time), 6000r/min (centrifuging for 2 times) and 9000r/min (centrifuging for 2 times), and when the pH value of the supernatant is more than 6.0, obtaining a multilayer Ti 3 C 2 Precipitating;
step 4, in the multilayer Ti 3 C 2 Adding deionized water into the precipitate, introducing continuous argon flow, performing ultrasonic treatment in 100W ultrasonic machine for 90min, centrifuging at 1500r/min for 40min to obtain supernatant as single layer or few layers of Ti 3 C 2 The volume concentration of the nano-sheet colloid aqueous solution is 4.85mg/mL;
step 5, dissolving 1.5g of urea in 20mL of absolute ethyl alcohol, and stirring for 40min on a magnetic stirrer;
step 6, measuring 10mL of Ti 3 C 2 Aqueous nanosheet colloid solution, adding it to ethanol, ti 3 C 2 The volume ratio of the colloidal aqueous solution to the ethanol is 1:2, centrifuging at 9000r/min for 5min to obtain Ti 3 C 2 Precipitating;
step 7, the Ti obtained above is used 3 C 2 Adding the precipitate into the ethanol solution containing urea, and stirring for 40min on a magnetic stirrer;
step 8, transferring the obtained mixed solution into a polytetrafluoroethylene lining, wherein the filling ratio is 50%, sealing the stainless steel hydrothermal reaction kettle, carrying out solvothermal reaction in a forced air drying oven, the reaction temperature is 200 ℃, the reaction time is 24 hours, cooling the reaction kettle to room temperature, carrying out centrifugal washing by using ethanol and deionized water until the supernatant is neutral, and obtaining nitrogen-doped Ti 3 C 2 Precipitating;
step 9, doping nitrogen with Ti 3 C 2 Adding deionized water into the precipitate, ultrasonically dispersing for 30min, vacuum filtering, and naturally air drying to obtain flexible self-supporting nitrogen-doped Ti 3 C 2 (N-Ti 3 C 2 ) And a thin film electrode.
Example 3
Flexible nitrogen-doped titanium carbide MXene thin-film electrode material with high volume-specific capacitance, wherein nitrogen atoms enter Ti 3 C 2 In the lattice, the interlayer spacing is enlarged, urea and Ti 3 C 2 The mass ratio of (A) to (B) is 2.0:0.0485.
the preparation method of the flexible nitrogen-doped titanium carbide MXene thin film electrode with high volume-to-volume ratio capacitance comprises the following steps:
step 1, adding deionized water and concentrated HCl into a polytetrafluoroethylene lining, and stirring for 15min on a magnetic stirrer to obtain HCl aqueous solution with the molar concentration of 9 mol/L; slowly adding LiF into the 9mol/L HCl aqueous solution, stirring on a magnetic stirrer for 15min, wherein the mass concentration of LiF is 0.1g/mL, and obtaining a mixed aqueous solution of HCl and LiF as an etching agent;
step 2, slowly adding Ti into the HCl and LiF mixed solution 3 AlC 2 Powder of Ti 3 AlC 2 The mass concentration of the Al layer is 0.05g/mL, continuous constant-temperature magnetic stirring is carried out in an oil bath pot, the oil bath temperature is 35 ℃, the magnetic stirring time is 24 hours, the magnetic stirring rotating speed is 600r/min, and the Al layer is etched away;
step 3, repeatedly centrifuging and washing the etched suspension by deionized water for 2min at 3500r/min (centrifugation 2)Twice), 6000r/min (3 times of centrifugation), 9000r/min (3 times of centrifugation), when the pH value of the supernatant is more than 6.0, obtaining multilayer Ti 3 C 2 Precipitating;
step 4, in the multilayer Ti 3 C 2 Adding deionized water into the precipitate, introducing continuous argon flow, performing ultrasonic treatment in 100W ultrasonic machine for 1 hr, centrifuging at 1500r/min for 30min to obtain supernatant as single-layer or few-layer Ti 3 C 2 The volume concentration of the nano-sheet colloid aqueous solution is 4.85mg/mL;
step 5, dissolving 2.0g of urea in 20mL of absolute ethyl alcohol, and stirring for 20min on a magnetic stirrer;
step 6, measuring 10mL of Ti 3 C 2 Aqueous nanosheet colloid solution, adding it to ethanol, ti 3 C 2 The volume ratio of the colloidal aqueous solution to the ethanol is 1:3, centrifuging at 9000r/min for 2min to obtain Ti 3 C 2 Precipitating;
step 7, the Ti obtained above is used 3 C 2 Adding the precipitate into the ethanol solution containing urea, and stirring for 20min on a magnetic stirrer;
and 8: transferring the obtained mixed solution into a polytetrafluoroethylene lining with the filling ratio of 40%, sealing the mixed solution by using a stainless steel hydrothermal reaction kettle, carrying out solvothermal reaction in a forced air drying oven at the reaction temperature of 200 ℃ for 24 hours, cooling the reaction kettle to room temperature, carrying out centrifugal washing by using ethanol and deionized water until the supernatant is neutral, and obtaining the nitrogen-doped Ti 3 C 2 Precipitating;
step 9, doping nitrogen with Ti 3 C 2 Adding deionized water into the precipitate, ultrasonically dispersing for 20min, vacuum filtering, and naturally air drying to obtain flexible self-supporting nitrogen-doped Ti 3 C 2 (N-Ti 3 C 2 ) And a thin film electrode.
FIG. 1 is nitrogen-doped Ti prepared in example 3 3 C 2 (N-Ti 3 C 2 ) Optical photograph and SEM image of film, from a picture, the prepared nitrogen-doped Ti 3 C 2 (N-Ti 3 C 2 ) The surface of the film is smooth and compact(ii) a As can be seen from the b diagram, the prepared nitrogen-doped Ti 3 C 2 (N-Ti 3 C 2 ) The film has good self-supporting and flexibility, and the integrity of the film can be still maintained after the film is bent by 180 degrees; c diagram is prepared nitrogen-doped Ti 3 C 2 (N-Ti 3 C 2 ) The microscopic surface of the film is flat and compact in a plane SEM image, and a d image is prepared nitrogen-doped Ti 3 C 2 (N-Ti 3 C 2 ) SEM image of the cross section of the film, therefore, it can be seen that the film is formed by stacking a plurality of two-dimensional nano sheets layer by layer, the interlayer distance is enlarged, the embedding and the extraction of electrolyte ions are facilitated, and the nitrogen doping of Ti is improved 3 C 2 (N-Ti 3 C 2 ) Electrochemical performance of the thin film electrode.
Example 4
The flexible nitrogen-doped titanium MXene thin film electrode material with high volume-specific capacitance has nitrogen atoms entering Ti 3 C 2 In the lattice, the interlayer spacing is enlarged, urea and Ti 3 C 2 The mass ratio of (A) to (B) is 3.0:0.0485.
the preparation method of the flexible nitrogen-doped titanium carbide MXene thin film electrode with high volume-to-volume ratio capacitance comprises the following steps:
step 1, adding deionized water and concentrated HCl into a polytetrafluoroethylene lining, and stirring for 15min on a magnetic stirrer to obtain HCl aqueous solution with the molar concentration of 9 mol/L; slowly adding LiF into the 9mol/L HCl aqueous solution, stirring on a magnetic stirrer for 15min, wherein the mass concentration of LiF is 0.1g/mL, and obtaining a mixed aqueous solution of HCl and LiF as an etching agent;
step 2, slowly adding Ti into the mixed solution of HCl and LiF 3 AlC 2 Powder of Ti 3 AlC 2 The mass concentration of the Al layer is 0.05g/mL, continuous constant-temperature magnetic stirring is carried out in an oil bath pot, the oil bath temperature is 35 ℃, the magnetic stirring time is 24 hours, the magnetic stirring rotating speed is 800r/min, and the Al layer is etched away;
step 3, repeatedly centrifuging and washing the etched suspension by deionized water for 2min at the centrifugal rotation speeds of 3500r/min (centrifuging for 2 times), 6000r/min (centrifuging for 3 times) and 9000r/min (centrifuging for 3 times) respectively, and standingWhen the pH value of the clear liquid is more than 6.0, multilayer Ti is obtained 3 C 2 Precipitating;
step 4, in the multilayer Ti 3 C 2 Adding deionized water into the precipitate, introducing continuous argon flow, performing ultrasonic treatment in 100W ultrasonic machine for 1 hr, centrifuging at 1500r/min for 30min to obtain supernatant as single layer or few layers of Ti 3 C 2 The volume concentration of the nano-sheet colloid aqueous solution is 4.85mg/mL;
step 5, dissolving 3.0g of urea in 20mL of absolute ethyl alcohol, and stirring for 30min on a magnetic stirrer;
step 6, measuring 10mL of Ti 3 C 2 Aqueous nanosheet colloid solution, adding it to ethanol, ti 3 C 2 The volume ratio of the colloid aqueous solution to the ethanol is 1:3, centrifuging at 9000r/min for 2min to obtain Ti 3 C 2 Precipitating;
step 7, the Ti obtained above is used 3 C 2 Adding the precipitate into the ethanol solution containing urea, and stirring for 30min on a magnetic stirrer;
step 8, transferring the obtained mixed solution into a polytetrafluoroethylene lining, wherein the filling ratio is 40%, sealing the stainless steel hydrothermal reaction kettle, carrying out solvothermal reaction in a forced air drying oven, wherein the reaction temperature is 200 ℃, the reaction time is 24 hours, cooling the reaction kettle to room temperature, carrying out centrifugal washing by using ethanol and deionized water until the supernatant is neutral, and obtaining nitrogen-doped Ti 3 C 2 Precipitating;
step 9, doping Ti in nitrogen 3 C 2 Adding deionized water into the precipitate, ultrasonically dispersing for 20min, vacuum filtering, and naturally air drying to obtain flexible self-supporting nitrogen-doped Ti 3 C 2 (N-Ti 3 C 2 ) And a thin film electrode.
FIG. 2 is pure phase Ti 3 C 2 Thin film and nitrogen-doped Ti prepared under different nitrogen doping amounts 3 C 2 XRD diffraction pattern of the thin film, wherein pure phase Ti 3 C 2 The film is obtained according to the process of the invention without the addition of urea in step 5, pure phase Ti 3 C 2 The film thickness at 2 theta is 7 DEGHas Ti shown therein 3 C 2 Characteristic diffraction peak of (002) crystal face; a to d are nitrogen-doped Ti prepared in examples 1 to 4 of the present invention, respectively 3 C 2 XRD diffraction pattern of the film, as can be seen from FIG. 2, nitrogen-doped Ti 3 C 2 Characteristic diffraction peak and pure phase Ti of thin film 3 C 2 The diffraction peaks of the films are consistent, which indicates that nitrogen doping cannot be carried out on Ti 3 C 2 Introducing a hetero-phase, and, in addition, nitrogen-doping Ti 3 C 2 The characteristic diffraction peak of the (002) crystal face of the film is shifted to the left due to N-Ti doping 3 C 2 The interlayer spacing of the film is increased, and the electrolyte ions are easier to be embedded and extracted due to the larger interlayer spacing, thereby being beneficial to doping Ti with nitrogen 3 C 2 The electrochemical performance of the thin film electrode is improved;
FIG. 3 is pure phase Ti 3 C 2 Film and nitrogen-doped Ti prepared under different nitrogen doping amounts 3 C 2 XPS survey of thin films in which pure phase Ti is present 3 C 2 The film is prepared according to the preparation method of the invention, urea is not added in the step 5, and a-d are nitrogen-doped Ti prepared in the embodiments 1-4 of the invention respectively 3 C 2 XPS full spectrum of thin films; as can be seen from FIG. 3, ti is doped in nitrogen 3 C 2 In addition to the characteristic peaks of Ti 2p, C1 s, O1 s and F1s in XPS survey of thin films, the characteristic peak of N1s is observed at 400eV, while pure phase Ti 3 C 2 No characteristic peak of N1s was observed in XPS survey of the film, indicating that nitrogen was successfully doped into Ti 3 C 2 In the crystal lattice of (a);
FIG. 4 is pure phase Ti 3 C 2 Electrochemical performance of thin film electrode of pure phase Ti 3 C 2 The film is obtained according to the preparation method of the invention, in step 5 without adding urea, and a is pure phase Ti 3 C 2 The Cyclic Voltammetry (CV) curves of the thin film electrode at different sweep rates can be seen from the graph a, pure phase Ti at different sweep rates 3 C 2 A pair of small redox peaks appeared in the CV curves of the thin film electrodes due to H + Electrolyte ion in Ti 3 C 2 Reversible oxidation of the surface takes placeCarrying out reduction reaction; b is pure phase Ti 3 C 2 The constant current charging and discharging (GCD) curve of the film electrode under different current densities can be seen from the graph b, and under different current densities, pure-phase Ti 3 C 2 The thin film electrodes all exhibited nearly symmetrical charge and discharge curves, indicating pure phase Ti 3 C 2 The thin-film electrode has good reversibility and coulombic efficiency;
FIG. 5 is a nitrogen-doped Ti prepared in example 3 3 C 2 Electrochemical performance of a thin film electrode, wherein a is the nitrogen-doped Ti prepared in example 3 3 C 2 Cyclic Voltammetry (CV) curves of the thin film electrode at different scan rates, as can be seen from the graph a, nitrogen is doped with Ti at different scan rates 3 C 2 A pair of obvious oxidation reduction peaks appear in the CV curves of the thin film electrode, and the peak is pure phase Ti with the peak shown in FIG. 4a 3 C 2 The CV curve comparison of the thin film electrode shows that under the same sweep rate, nitrogen is doped with Ti 3 C 2 The larger CV curve area of the thin film electrode is due primarily to nitrogen doping into Ti 3 C 2 More reactive sites are provided in the crystal lattice, so that nitrogen is doped with Ti 3 C 2 More oxidation-reduction reactions occur on the surface of the thin film electrode, and the nitrogen-doped Ti can be effectively improved 3 C 2 The specific capacitance of the thin film electrode; b is the nitrogen-doped Ti prepared in example 3 3 C 2 The constant current charging and discharging (GCD) curve of the thin film electrode under different current densities can be seen from the graph b, under different current densities, nitrogen is doped with Ti 3 C 2 The thin film electrodes all show almost symmetrical charge-discharge curves, which shows that the nitrogen dopes Ti 3 C 2 The thin-film electrode also has good reversibility and coulombic efficiency, and in addition, pure phase Ti is shown in figure 4b 3 C 2 The comparison of GCD curves of the thin film electrodes shows that under the same current density, nitrogen is doped with Ti 3 C 2 The thin film electrode has longer charge and discharge time, which indicates that nitrogen is doped with Ti 3 C 2 The specific capacitance of the thin film electrode is obviously increased;
FIG. 6 is pure phase Ti 3 C 2 Film and nitrogen-doped Ti prepared under different nitrogen doping amounts 3 C 2 Film electrode at different sweeping speedsVolume specific capacitance value of, wherein, pure phase Ti 3 C 2 The film is prepared according to the preparation method of the invention, urea is not added in the step 5, and a-d are nitrogen-doped Ti prepared in the embodiments 1-4 of the invention respectively 3 C 2 The volume ratio capacitance value of the film electrode under different sweep speeds. As can be seen from FIG. 6, pure phase Ti 3 C 2 The sweep rate of the film electrode is 2mV s -1 When the specific capacitance is 2064.3F cm -3 When the sweep rate is increased to 500mV s -1 When the capacitance is reduced to 317.9F cm -3 The capacity retention was only 15.4%; as can be seen from the a-d curves, all nitrogen-doped Ti 3 C 2 The volume specific capacitance of the film electrode is obviously higher than that of pure phase Ti 3 C 2 The height of the thin film electrode indicates that nitrogen doping can effectively increase Ti 3 C 2 The volume specific capacitance of (a); furthermore, nitrogen-doped Ti prepared in example 3 of the present invention 3 C 2 The membrane electrode has the highest volume specific capacitance (c-curve) when the sweep rate is 2mV s -1 When the capacitance is high, the volume specific capacitance reaches 2898.5F cm -3 When the sweep rate is increased to 500mV s -1 The volume specific capacitance can be kept at 1361.6F cm -3 The capacity retention rate was increased to 47.0%, exhibiting excellent rate performance.
The above examples demonstrate that the nitrogen doping method provided by the present invention can effectively improve Ti content 3 C 2 The invention can prepare the flexible self-supporting nitrogen-doped Ti with high volume specific capacitance by the preparation method 3 C 2 The thin film electrode can be applied to flexible and miniature super capacitors.

Claims (10)

1. The preparation method of the flexible nitrogen-doped titanium carbide MXene thin film electrode with the high volume-to-volume ratio capacitance is characterized by comprising the following steps:
step 1, adding deionized water and concentrated HCl into a polytetrafluoroethylene lining, and uniformly stirring to obtain an HCl aqueous solution; slowly adding LiF into the HCl aqueous solution, and uniformly stirring to obtain a mixed aqueous solution of HCl and LiF as an etching agent;
in the step 2, the step of mixing the raw materials,slowly adding Ti into the HCl and LiF mixed solution prepared in the step 1 3 AlC 2 Continuously stirring the powder in an oil bath pan by constant temperature magnetic force to etch off an Al layer;
step 3, repeatedly centrifuging and washing the etched suspension by using deionized water to obtain a plurality of layers of Ti 3 C 2 Precipitating;
step 4, in the multi-layer Ti 3 C 2 Adding deionized water into the precipitate, introducing continuous argon flow, ultrasonically stripping, centrifuging to obtain supernatant as single layer or few layers of Ti 3 C 2 A nanosheet colloidal aqueous solution;
step 5, dissolving urea in absolute ethyl alcohol, and uniformly stirring;
step 6, measuring a certain volume of Ti 3 C 2 Adding the nano sheet colloid aqueous solution into ethanol, and centrifuging to obtain Ti 3 C 2 Precipitating;
step 7, the Ti obtained above is used 3 C 2 Adding the precipitate into the ethanol solution containing urea, and uniformly stirring;
step 8, transferring the mixed solution obtained in the step 7 into a polytetrafluoroethylene lining, sealing the polytetrafluoroethylene lining by using a stainless steel hydrothermal reaction kettle, carrying out solvothermal reaction in a forced air drying oven, cooling the reaction kettle to room temperature, and centrifugally washing the reaction kettle by using ethanol and deionized water to obtain nitrogen-doped Ti 3 C 2 Precipitating;
step 9, doping Ti in nitrogen 3 C 2 Adding deionized water into the precipitate, performing ultrasonic dispersion, vacuum filtration, and naturally air drying to obtain flexible self-supporting nitrogen-doped Ti 3 C 2 And a thin film electrode.
2. The method for preparing the high-volume-ratio-capacitance flexible nitrogen-doped titanium carbide MXene thin film electrode according to claim 1, wherein the molar concentration of the HCl aqueous solution in the step 1 is 9mol/L, and the mass concentration of LiF is 0.1g/mL; the two times of stirring are 15-30 min.
3. The highbody of claim 1The preparation method of the specific capacitance-integrating flexible nitrogen-doped titanium carbide MXene film electrode is characterized in that in the step 2, the oil bath temperature is 35-45 ℃, the magnetic stirring time is 24-48 h, and the magnetic stirring speed is 400-800 r/min; ti 3 AlC 2 The mass concentration of (3) was 0.05g/mL.
4. The method for preparing the high-volumetric-specific-capacitance flexible nitrogen-doped titanium carbide MXene thin film electrode according to claim 1, wherein the centrifugation time required for repeated centrifugation and washing with deionized water in the step 3 is 2-5 min, and the centrifugation rotation speed is 3500r/min and 1-2 times respectively; 6000r/min, centrifuging for 2-3 times; centrifuging for 2-3 times at 9000 r/min; the pH value of the supernatant fluid obtained by centrifugal washing is not less than 6.0.
5. The method for preparing the high-volume-ratio-capacitance flexible nitrogen-doped titanium carbide MXene thin film electrode according to claim 1, wherein in the step 4, the ultrasonic power is 90-100W, the ultrasonic time is 40-90min, and Ti is added into the mixed solution of the titanium and the MXene thin film electrode, and the mixed solution of the titanium and the MXene thin film electrode is Ti-doped into the mixed solution of the titanium and the MXene thin film electrode 3 C 2 The volume concentration of the nano-sheet colloid aqueous solution is 3.0-5.5 mg/mL; the centrifugal speed is 1400-1600 r/min, and the centrifugal time is 20-40 min.
6. The method for preparing the high-volume-ratio-capacitance flexible nitrogen-doped titanium carbide MXene thin film electrode as claimed in claim 1, wherein the urea and Ti added in step 5 3 C 2 The mass ratio of (A) to (B) is 0.5-4.0: 0.0485, and the stirring time is 20-40 min.
7. The method for preparing the high-volume-ratio-capacitance flexible nitrogen-doped titanium carbide MXene thin film electrode as claimed in claim 1, wherein in the step 6, ti is added 3 C 2 The volume ratio of the colloid aqueous solution to the ethanol is 1:1 to 3; the centrifugal speed is 6000 to 10000r/min, the centrifugal time is 2 to 5min, and the stirring time in the step 7 is 20 to 40min.
8. The method for preparing the high-volume-ratio-capacitance flexible nitrogen-doped titanium carbide MXene thin film electrode according to claim 1, wherein the filling ratio of the mixed solution in the polytetrafluoroethylene lining in the step 8 is 35-50%, the solvothermal reaction temperature is 200 ℃, and the reaction time is 24h; washing with ethanol and deionized water until the supernatant is neutral; the ultrasonic dispersion time in the step 9 is 10-30 min.
9. The high-volume-ratio-capacitance flexible nitrogen-doped titanium carbide MXene thin film electrode is characterized by being prepared by the preparation method of the high-volume-ratio-capacitance flexible nitrogen-doped titanium carbide MXene thin film electrode as claimed in any one of claims 1 to 9.
10. The application of the high-volume-ratio-capacitance flexible nitrogen-doped titanium carbide MXene thin film electrode prepared by the preparation method of the high-volume-ratio-capacitance flexible nitrogen-doped titanium MXene thin film electrode disclosed by any one of claims 1-9 in a flexible supercapacitor.
CN202211470770.3A 2022-11-23 2022-11-23 Preparation method and application of flexible nitrogen-doped titanium carbide MXene thin-film electrode with high volume-to-volume ratio capacitance Pending CN115938818A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117116671A (en) * 2023-08-30 2023-11-24 哈尔滨工业大学 Preparation method, product and application of MXene film based on coagulation self-assembly

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117116671A (en) * 2023-08-30 2023-11-24 哈尔滨工业大学 Preparation method, product and application of MXene film based on coagulation self-assembly

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