CN113046765B

CN113046765B - Foamed nickel loaded Fe2O3@Ni3S2Preparation method of OER (organic electroluminescent) electrocatalyst with composite structure

Info

Publication number: CN113046765B
Application number: CN202110304590.7A
Authority: CN
Inventors: 唐少春; 乔清山; 张晟
Original assignee: Nanjing University
Current assignee: Nanjing University
Priority date: 2021-03-22
Filing date: 2021-03-22
Publication date: 2022-07-12
Anticipated expiration: 2041-03-22
Also published as: CN113046765A

Abstract

The invention discloses a foam nickel-loaded Fe₂O₃@Ni₃S₂The preparation method of the OER electrocatalyst with the composite structure sequentially comprises the following steps of: s1 foam nickel base material pretreatment, S2 Ni preparation₃S₂Preparation of Fe from NF precursor S3₂O₃@Ni₃S₂and/NF. The invention solves the problem that the NF surface contains oxide impurities through acid treatment, the modification ensures that the load material is easy to grow on the substrate, firstly Ni3S2 nano wires are etched and grown on the NF surface, and then string-ball-shaped Fe grows on the surface of the nano wires₂O₃Nanoparticles, produced Fe₂O₃@Ni₃S₂the/NF material has high specific surface area, obviously improves the efficiency of electrocatalytic water decomposition for producing oxygen, and has very low overpotential under high current density, 100mA/cm²The overpotential of the catalyst is only 223mV under the current density, and the catalyst has excellent OER electrocatalytic performance under the high current density; the invention has low cost, easy control and scale production and good industrial application prospect; meanwhile, the applicability is strong, and the method can be popularized to the preparation and large-scale production of other electrocatalysis devices.

Description

Foamed nickel loaded Fe2O3@Ni3S2Preparation method of OER (organic electroluminescent) electrocatalyst with composite structure

Technical Field

The invention relates to a preparation process of an efficient electrocatalytic water decomposition Oxygen Evolution (OER) catalyst, in particular to a foamed nickel-loaded Fe₂O₃@Ni₃S₂A preparation method of an OER electrocatalyst with a composite structure.

Background

Hydrogen energy is a very superior new energy source, and has the main advantages that: high combustion heat value, cleanness, no pollution, rich resources, wide application range and the like. The key technology for developing hydrogen energy comprises two aspects: on one hand, the problem of hydrogen production is solved; on the other hand, the problem of hydrogen storage and transportation is solved. The selection of the hydrogen production method is crucial to the wide use of hydrogen. The hydrogen production method mainly comprises the steps of water electrolysis oxygen production, water photolysis hydrogen production, mineral fuel hydrogen production, biomass hydrogen production, hydrogen production by other hydrogen-containing substances, recovery of hydrogen produced by various chemical processes and the like, wherein the hydrogen production by electrocatalytic decomposition of water is the most main way for large-scale hydrogen production. In the electrocatalytic water decomposition process, the OER process is a 4-electron transfer process, but it is critical to the overall water electrolysis process. It is imperative to find suitable catalysts through research.

The nickel-based catalyst has low preparation cost, is easy to obtain, and has potential in industrial application prospect. Researches show that the pure nickel metal material cannot provide high catalytic activity, and if a wiener structure is designed on the surface of the material, the electrocatalytic performance of the material can be obviously improved. This is because the support can increase the activity by interacting with the catalyst, or provide more contact area for the catalyst, etc.

Disclosure of Invention

The invention aims to provide a nickel foam loaded Fe₂O₃@Ni₃S₂The preparation method of the OER electrocatalyst with the composite structure solves the problem that the NF surface contains oxide impurities through acid treatment, the modification enables the load material to easily grow on the substrate, and firstly, Ni grows on the NF surface through etching₃S₂Nanowires are then grown with Fe clusters on the surface of the nanowires₂O₃Nanoparticles, produced Fe₂O₃@Ni₃S₂the/NF material has high specific surface area, obviously improves the efficiency of electrocatalytic water decomposition for producing oxygen, and has very low overpotential under high current density, 100mA/cm²The overpotential at the current density of (a) is only 223 mV. The method has important significance for designing and preparing the high-efficiency water-splitting OER electrocatalyst.

The embodiment of the application discloses a foam nickel loaded Fe₂O₃@Ni₃S₂The preparation method of the OER electrocatalyst with the composite structure comprises the following steps:

s1 pretreatment of the foamed nickel substrate: cutting a metal foam Nickel (NF) substrate to 1.0-4.0 cm²Placing the rectangle in hydrochloric acid with the concentration of 0.1-1.0M, carrying out ultrasonic treatment for 5-30 min, cleaning the rectangle with ultrapure water for three times to remove the hydrochloric acid, finally cleaning the rectangle with absolute ethyl alcohol, and drying the rectangle in a vacuum oven after cleaning to obtain the pretreated bubblesA nickel foam substrate;

s2 preparation of Ni₃S₂The NF precursor: respectively measuring 16ml of anhydrous ethanol and 16ml of anhydrous ethylenediamine, adding the anhydrous ethanol and the anhydrous ethylenediamine into a beaker, carrying out magnetic stirring for 10min to uniformly mix the anhydrous ethanol and the anhydrous ethylenediamine, then adding 2mmol of sublimed sulfur, continuing the magnetic stirring for 10min to fully dissolve the sublimed sulfur, after the stirring is finished, transferring the mixed solution and the pretreated foamed nickel substrate prepared in the step S1 into a 50ml polytetrafluoroethylene lining, placing the lining into a reaction kettle and packaging, placing the reaction kettle into a constant-temperature blast drying box, reacting at the temperature of 160 ℃ for 6h, naturally cooling after the reaction is finished, taking out a sample, washing the sample for multiple times by using ultrapure water, then placing the sample into a vacuum oven to dry to obtain Ni₃S₂a/NF precursor;

s3 preparation of Fe₂O₃@Ni₃S₂/NF: 0.1-1.0 mmol of FeCl₂·4H₂Dissolving O and 0.1-1.0 mmol of hexamethylenetetramine in 30-50 ml of ultrapure water, stirring and dissolving by using a glass rod, and mixing the mixed solution with the Ni prepared in the step S2₃S₂Transferring the/NF precursor into a 50ml reaction kettle lining together, filling the reaction kettle, placing the reaction kettle in a blast drying box, reacting for 3-6 h at 60-100 ℃, naturally cooling after the reaction is finished, washing the reaction kettle with ultrapure water for multiple times, and drying the reaction kettle in a vacuum oven after the washing is finished to obtain Fe₂O₃@Ni₃S₂/NF。

Preferably, in the above Fe₂O₃@Ni₃S₂In the preparation method of the/NF composite structure OER electrocatalyst, in the step S3, the obtained Fe₂O₃@Ni₃S₂the/NF particles grow in a cluster shape on the nano-wires, and the average particle size of the particles is 80-100 nm.

Compared with the prior art, the invention has the advantages that:

1. the invention solves the problem that the NF surface contains oxide impurities through acid treatment, the modification ensures that the load material is easy to grow on the substrate, and Ni is etched and grown on the NF surface firstly₃S₂Nanowires are then grown with Fe clusters on the surface of the nanowires₂O₃Nanoparticles, F obtainede₂O₃@Ni₃S₂the/NF material has high specific surface area, obviously improves the efficiency of electrocatalytic water decomposition for producing oxygen, and has very low overpotential under high current density, 100mA/cm²The overpotential of the catalyst is only 223mV under the current density, and the catalyst has excellent OER electrocatalytic performance under the high current density;

2. the invention has low cost, easy control and large scale, has good industrial application prospect, has strong applicability and can be popularized to the preparation and large scale production of other electrocatalysis devices.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1(a-d) Fe obtained in example 1₂O₃@Ni₃S₂SEM images of different magnifications of/NF catalyst.

FIG. 2 Fe obtained in example 1₂O₃@Ni₃S₂XRD pattern of/NF electrode material.

FIG. 3 characterisation of NF, Ni₃S₂/NF Fe prepared in example 1₂O₃@Ni₃S₂Oxygen evolution polarization curve of/NF electrode material in 1M KOH electrolyte.

FIG. 4 Fe obtained in example 2₂O₃@Ni₃S₂SEM image of/NF electrode material and comparison of catalytic performance. FIG. 4(a-c) shows 0.2mmol, 0.4mmol, 0.6mmol of Fe²⁺SEM pictures of the samples were made at the molar addition. FIG. 4(d) is a comparison of catalytic performance.

FIG. 5 Fe obtained in example 3₂O₃@Ni₃S₂SEM image and catalytic performance comparison of/NF electrode material. FIGS. 5(a-c) are graphs showing the corresponding materials at 80 deg.C, 90 deg.C, and 100 deg.CSurface topography. FIG. 5(d) is a comparison of catalytic performance.

Detailed Description

Foamed nickel supported Fe in connection with the present invention₂O₃@Ni₃S₂The present invention will be further understood from the following detailed description of an electrocatalyst composite material and its application in conjunction with examples, and it should be understood that the examples described are only a part of the examples, and not all of the examples. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Example 1

S1 pretreatment of the foamed nickel substrate: cutting a metal foam Nickel (NF) base material into a rectangle with the thickness of 1.0cm multiplied by 4.0cm, placing the rectangle in hydrochloric acid with the concentration of 1.0M, carrying out ultrasonic treatment for 10min, cleaning the rectangle with ultrapure water for three times to remove the hydrochloric acid, finally cleaning the rectangle with absolute ethyl alcohol, and drying the rectangle in a vacuum oven after cleaning to obtain a pretreated foam nickel base material;

s3 preparation of Fe₂O₃@Ni₃S₂/NF: 0.4mmol of FeCl₂·4H₂O and 0.5mmol of hexamethylenetetramine were dissolved in 40ml of ultrapure water, dissolved with stirring with a glass rod, and the mixed solution was mixed with Ni prepared in step S2₃S₂/NF precursor rotating togetherPutting the mixture into a 50ml reaction kettle lining, installing the reaction kettle, placing the reaction kettle in a forced air drying oven, reacting for 5 hours at 90 ℃, naturally cooling after the reaction is finished, washing the reaction kettle for multiple times by using ultrapure water, and drying the reaction kettle in a vacuum drying oven after the washing is finished to obtain Fe₂O₃@Ni₃S₂/NF。

FIGS. 1(a-d) shows Fe obtained in example 1₂O₃@Ni₃S₂SEM images of different magnifications of/NF catalyst. FIG. 1(a-b) shows that iron oxide grows uniformly on the surface of the nanowire; the high-power scanning photographs of fig. 1(c-d) clearly show that the granular iron oxide is distributed on the surface of the nanowires in a cluster-like shape, and the granules are not closely connected but appear at intervals.

FIG. 2 shows Fe obtained in example 1₂O₃@Ni₃S₂XRD pattern of/NF electrode material. For Fe₂O₃@Ni₃S₂The phase of the/NF electrode material is calibrated, the diffraction peak marked by the black square sheet corresponds to the Ni standard card, and the diffraction peak marked by the blue plum blossom corresponds to the Ni standard card₃S₂A standard card. It is found that besides the foamed nickel as the base material, Ni with better crystallinity grows on the surface₃S₂Nanowires, Fe was also found₂O₃The phase of (1), the diffraction peaks of red peach at 24.1 deg.C, 33.1 deg.C, 35.6 deg.C, 49.4 deg.C, and 54.0 deg.C respectively correspond to Fe₂O₃The standard card PDF #85-0599 has (012), (104), (110), (024) and (116) crystal faces, wherein, the intensity of the diffraction peak at 35.6 ℃ corresponding to the (110) crystal face is stronger, which indicates that the crystallinity of the crystal face is better.

FIG. 3 characterisation of NF, Ni₃S₂/NF Fe prepared in example 1₂O₃@Ni₃S₂The oxygen evolution polarization curve of the NF electrode material in 1M KOH electrolyte; pure NF base material with poor OER performance, Ni₃S₂The OER performance of the/NF material is remarkably improved compared with that of a substrate material and is 50mA/cm²And 100mA/cm²The corresponding OER overpotentials at current density of (a) are 355mV and 508mV, respectively; fe₂O₃@Ni₃S₂OER performance of/NF electrode material is compared with Ni₃S₂The NF material is improved more obviously at 50mA/cm²And 100mA/cm²The corresponding OER overpotentials at current densities of (a) were 215mV and 223mV, respectively, and the overpotentials were reduced by 140mV and 285mV, respectively.

Example 2

FIG. 4 shows Fe obtained in example 2₂O₃@Ni₃S₂SEM image and catalytic performance comparison of/NF electrode material. To study Fe²⁺The influence of the introduced amount on the OER catalytic performance and the morphology of the material is set in the experiment, and four different Fe are set²⁺The molar weights of 0.2mmol, 0.4mmol, 0.6mmol and 0.8mmol were added, and SEM pictures of the samples at the first three molar weights are shown in FIGS. 4 (a-c). FIG. (a) shows that Fe²⁺Adding Ni in small molar amounts₃S₂Substances growing on the surfaces of the nanowires are not uniform, and many substances extend between the nanowires with the nanowires as edges and have a dust length in a curved state, and in addition, granular substance aggregates exist. As can be seen from FIG. (b), with Fe²⁺Addition of increasing molar amount of Fe₂O₃Nanoparticles in Ni₃S₂The nanowires are distributed at intervals, show the state of nanowire cluster balls and are uniformly distributed on the whole. Panel (c) clearly shows that the increase in Fe continues²⁺Adding Fe when the molar weight reaches 0.6mmol₂O₃The size of the nano-sheets is obviously increased, the nano-particles are in a mutually overlapped state, the size of the nano-particles is also obviously increased, the nano-particles grow into small balls with the size of about 500nm from the original nano-particles, and the existence of nano-wires can be observed at the middle position of the picture. In the SEM photograph corresponding to the 0.8mmol addition, the particles continued to grow and a large amount of agglomeration occurred. It can be seen that Fe is the morphology of the grown material²⁺The molar amount added is an optimum value, i.e., 0.4mmol, and Fe is determined according to the OER performance test data of graph (d)²⁺Adding 50mA/cm of solution with molar weight of 0.2mmol, 0.4mmol, 0.6mmol and 0.8mmol respectively²Corresponding over-potentials at the current densities of (a) are 241mV, 215mV, 287mV, 461 mV, 100mA/cm²The overpotentials corresponding to the first three molar samples at the current density of (1) are 396mV, 322mV, 486mV (Fe)²⁺When the molar weight is added to be 0.8mmol, the current density does not reach 100mA/cm in a tested voltage window²)。

Example 3

FIG. 5 shows Fe obtained in example 3₂O₃@Ni₃S₂SEM image and catalytic performance comparison of/NF electrode material. In order to study the influence of the hydrothermal reaction temperature on the OER performance and morphology of the material, four hydrothermal reaction temperatures of 80 ℃, 90 ℃, 100 ℃ and 110 ℃ were set in the experiment, and the surface morphology of the corresponding material at 80 ℃, 90 ℃ and 100 ℃ is shown in FIG. 5 (a-c). FIG. (a) shows that the hydrothermal reaction temperature at 80 ℃ is only Ni₃S₂A small amount of nano particles grow on the surface of the nano wire, so the surface appearance and Ni of the sample under the condition₃S₂the/NF precursor materials are very similar; as can be seen from the graph (b), the nano particles are uniformly distributed along the extending direction of the nano wire and are coated on the Ni at intervals₃S₂On the nanowires. When the hydrothermal temperature is 100 ℃, the morphology of the material shows the state shown in the graph (c), Ni₃S₂The space around the nanowires is filled with larger iron oxide particles, which hinder the transport of active species and charges during the oxygen evolution reaction, resulting in a decrease in OER performance. The sample prepared under the condition of 110 ℃ has larger particles than the sample prepared under the condition of (c), and obvious agglomeration phenomenon occurs. The structure of the material determines the performance of the material, and the graph (d) shows that the electrode material prepared at four hydrothermal reaction temperatures of 80 ℃, 90 ℃, 100 ℃ and 110 ℃ is 50mA/cm²The corresponding overpotentials at the current density of (a) are 244mV, 215mV, 221mV, 232mV, 100mA/cm²The corresponding overpotentials at current density of (a) are 380mV, 322mV, 345mV, and 405mV, respectively. Thus, Fe was produced under hydrothermal conditions of 90 deg.C₂O₃@Ni₃S₂the/NF electrode material has excellent OER catalytic performance and surface appearance.

Claims

1. Foamed nickel loaded Fe₂O₃@Ni₃S₂The preparation method of the OER electrocatalyst with the composite structure is characterized by comprising the following steps of:

s1 pretreatment of the foamed nickel substrate: cutting a metal foam Nickel (NF) base material into a rectangle of 1.0-4.0 cm2, placing the rectangle in hydrochloric acid with the concentration of 0.1-1.0M, carrying out ultrasonic treatment for 5-30 min, cleaning the rectangle with ultrapure water for three times to remove hydrochloric acid, finally cleaning the rectangle with absolute ethyl alcohol, and drying the rectangle in a vacuum oven after cleaning to obtain a pretreated foam nickel base material;

s2 preparation of Ni₃S₂The NF precursor: respectively measuring 16mL of anhydrous ethanol and 16mL of anhydrous ethylenediamine, adding the anhydrous ethanol and the anhydrous ethylenediamine into a beaker, carrying out magnetic stirring for 10min to uniformly mix the anhydrous ethanol and the anhydrous ethylenediamine, then adding 2mmol of sublimed sulfur, continuing the magnetic stirring for 10min to fully dissolve the sublimed sulfur, after the stirring is finished, transferring the mixed solution and the pretreated foamed nickel substrate prepared in the step S1 into a 50mL polytetrafluoroethylene lining, placing the lining into a reaction kettle, packaging the reaction kettle, placing the reaction kettle into a constant-temperature blast drying box, reacting at the temperature of 160 ℃ for 6h, naturally cooling after the reaction is finished, taking out a sample, washing the sample for multiple times by using ultrapure water, then placing the sample into a vacuum oven for drying to obtain Ni₃S₂a/NF precursor;

s3 preparation of Fe₂O₃@Ni₃S₂/NF: adding 0.1-1.0 mmol of FeCl₂·4H₂Dissolving O and 0.1-1.0 mmol of hexamethylenetetramine in 30-50 mL of ultrapure water, stirring and dissolving the solution by using a glass rod, and mixing the mixed solution with the Ni prepared in the step S2₃S₂Transferring the/NF precursor into a 50mL reaction kettle lining together, loading the reaction kettle, placing the reaction kettle in a blast drying oven, reacting for 3-6 h at 60-100 ℃, naturally cooling after the reaction is finished, washing with ultrapure water for multiple times, and drying in a vacuum oven after the washing is finished to obtain Fe₂O₃@Ni₃S₂/NF。

2. Fe-supported nickel foam according to claim 1₂O₃@Ni₃S₂A method for preparing an OER electrocatalyst with a composite structure, which is characterized in that in the step S3, Fe is obtained₂O₃@Ni₃S₂the/NF particles grow in a string-ball shape on the nano-wires, and the average particle size of the particles is 80-100 nm.