CN115505959A - Ni/Ni (OH) with hierarchical heterostructures 2 -NiCo 2 O 4 /MF catalytic electrode - Google Patents

Ni/Ni (OH) with hierarchical heterostructures 2 -NiCo 2 O 4 /MF catalytic electrode Download PDF

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CN115505959A
CN115505959A CN202211212020.6A CN202211212020A CN115505959A CN 115505959 A CN115505959 A CN 115505959A CN 202211212020 A CN202211212020 A CN 202211212020A CN 115505959 A CN115505959 A CN 115505959A
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nico
nickel
electrodeposition
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foam
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王建芝
喻发全
郭自依
刘怡恒
蔡宁
薛亚楠
李辉
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Wuhan Institute of Technology
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    • C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
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    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
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    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
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    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
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Abstract

The invention relates to a Ni/Ni (OH) with a hierarchical heterostructure 2 ‑NiCo 2 O 4 The preparation method and the application of the/MF catalytic electrode. Firstly, preparing a precursor liquid by using cobalt salt, nickel salt and urea, then adding foam metal cleaned in advance into the precursor liquid to carry out hydrothermal reaction, thereby obtaining Ni and Co bimetal hydroxide foam metal loaded with a one-dimensional nano array structure, and then heating and annealing the foam metal to obtain NiCo of the one-dimensional nano array structure 2 O 4 /MF, for NiCo in electrolytes containing nickel sulfamate and boric acid 2 O 4 /NF working electrode is subjected to electrodeposition reaction to finally obtain Ni/Ni (OH) with hierarchical heterostructure 2 ‑NiCo 2 O 4 a/MF catalytic electrode. The catalytic electrode material provided by the invention has excellent electrocatalytic performance and electrocatalytic hydrogen evolution stability, and the whole preparation method is relativeThe method is simple, raw materials are easy to obtain, industrial large-scale production can be realized, and the method has a good application prospect in the field of hydrogen energy sources.

Description

Having a hierarchical heterostructureNi/Ni(OH) 2 -NiCo 2 O 4 /MF catalytic electrode
Technical Field
The invention relates to the technical field of electrocatalysis and composite materials, in particular to Ni/Ni (OH) with a hierarchical heterostructure 2 -NiCo 2 O 4 A/MF catalytic electrode, a preparation method and application thereof.
Background
In recent years, the world faces a severe energy crisis, and with the increasing population, the demand of people for energy is higher and higher. The total global energy demand was 17TW in 2010, and scientists predicted that the total global energy demand would grow to 27TW in 2040. Fossil fuels have the advantages of high energy density, easy use and the like, and are the main energy fuels in the world for the past two centuries, thus playing a vital role in the development of the industry and technology in the world. Although gas and oil are still able to meet the global demand for energy in the foreseeable future, many problems remain with the exploitation and use of these traditional fossil energy sources.
Hydrogen is a sustainable novel energy carrier, has the advantages of zero carbon emission, high energy density and the like, and is considered as the most promising fossil fuel substitute. In the preparation process of hydrogen, a catalyst is required, and the chemical adsorption free energy delta G of the surface of the catalyst to hydrogen intermediates H Is an important factor affecting the performance of the catalyst. For high performance catalysts, Δ G H Typically close to 0.
Recently, ni (OH) has been reported 2 Can react with OH in water molecule - Interaction occurs to promote dissociation of the water molecules, whereupon the resulting hydrogen intermediates can be adsorbed by other catalytically active species near the surface and eventually recombine into hydrogen molecules.
In the microstructure of the catalyst, the effective and fast substance transmission channel is beneficial to the escape of hydrogen generated by the reaction, thereby promoting the forward progress of the whole catalytic reaction and further improving the catalytic efficiency of the catalyst. The nano-array can provide a large specific surface area structurally, which is an important factor in achieving high catalytic activity of the catalyst.
The invention combines the solvothermal method and the high-temperature annealing treatment, and can vertically grow a layer of one-dimensional NiCo on the surface of the Foam Metal (MF) 2 O 4 The nano array takes the one-dimensional array structure as a substrate, and a layer of catalytic active substances grows on the surface of the substrate to form a hierarchical heterostructure. Compared with a method of simply growing a layer of catalytic active substance on the foam metal, the catalytic performance of the material with the hierarchical heterostructure is greatly improved.
Disclosure of Invention
It is an object of the present invention to provide a Ni/Ni (OH) with a hierarchical heterostructure 2 -NiCo 2 O 4 The preparation method of the/MF catalytic electrode mainly comprises the following steps: (a) Dissolving cobalt salt, nickel salt and urea in water to obtain a precursor liquid; (b) Adding the foam metal into the precursor liquid for hydrothermal reaction to obtain Ni and Co bimetal hydroxide foam metal loaded with a one-dimensional nano array structure; (c) Carrying out heat treatment on the product prepared in the step (b) to obtain NiCo with a one-dimensional nano array structure 2 O 4 a/MF; (d) With NiCo 2 O 4 the/MF is used as a working electrode, and a hierarchical heterostructure Ni/Ni (OH) is prepared by means of electrodeposition 2 -NiCo 2 O 4 a/MF catalytic electrode.
Further, the cobalt salt in step (a) is selected from at least one of cobalt sulfate, cobalt nitrate, cobalt acetate, cobalt chloride or a hydrate thereof, and the nickel salt is selected from at least one of nickel chloride, nickel nitrate or a hydrate thereof.
Further, in the step (a), the molar ratio of the cobalt salt to the nickel salt to the urea is 3-2.
Further, the foamed metal in step (b) is selected from one of foamed nickel, foamed copper, foamed iron and foamed zinc, and the foamed metal needs acid washing, alcohol washing and water washing before use so as to remove oxides, oil stains, impurities and the like on the surface of the foamed metal.
Further, the hydrothermal reaction temperature in the step (b) is 100-200 ℃, and the heat preservation time is 2-8h.
Further, the heat treatment temperature in the step (c) is 300-500 ℃, the heat treatment time is 100-200min, the heating rate and the cooling rate are both 4-8 ℃/min, and the heat treatment atmosphere is air atmosphere.
Further, the specific process of step (d) is as follows: with NiCo 2 O 4 The method comprises the following steps of (1) taking/MF as a working electrode and Pt wires as a counter electrode, and building a standard two-electrode electrodeposition system; and (3) inserting the two electrodes into the electrolyte for electrodeposition, and finally taking out, cleaning and drying.
Further, the electrolyte is a mixture of nickel sulfamate, boric acid and deionized water, and an acid reagent (such as sulfuric acid) is added in the electrodeposition process to adjust the pH of the electrolyte to 3.0-5.0.
Furthermore, the molar ratio of the nickel sulfamate to the boric acid in the electrolyte is 20-30.
Further, the electrodeposition temperature is normal temperature, the electrodeposition time is 100-3000s, the electrodeposition mode is constant current density, and the current density is controlled at-60 mA/cm 2 To-40 mA/cm 2 。
Another object of the present invention is to provide a Ni/Ni (OH) with a hierarchical heterostructure 2 -NiCo 2 O 4 a/MF catalytic electrode.
It is a further object of the present invention to provide the above-described Ni/Ni (OH) with a hierarchical heterostructure 2 -NiCo 2 O 4 The application of the/MF catalytic electrode in the aspect of electrocatalytic hydrogen evolution.
Compared with the existing similar catalyst material and the preparation method thereof, the invention has the beneficial effects that:
(1) The invention takes foam metal as a substrate, combines a solvothermal method, high-temperature calcination and electrodeposition, and leads a conductive core NiCo 2 O 4 With the catalytically active material Ni/Ni (OH) 2 In combination, the Ni/Ni (OH) with a hierarchical heterostructure is successfully prepared on the surface of the foam metal 2 -NiCo 2 O 4 And (4) nano arrays.
(2) The invention is NiCo with a one-dimensional array structure 2 O 4 As a substrate, ni/Ni (OH) as a catalytically active material is supported thereon 2 A hierarchical heterostructure is formed, the electrochemical active area of the catalytic electrode is obviously improved, more catalytic active sites are exposed, and in addition, a plurality of gaps exist among the array structures, and the gaps can provide smooth and effective channels for mass transfer.
(3) The invention obtains optimized Ni/Ni (OH) 2 -NiCo 2 O 4 the/NF has excellent electro-catalytic hydrogen evolution performance in a KOH aqueous solution with the concentration of 1M and has the current density of 10 mA-cm -2 The overpotential is only 60mV. In addition, the catalytic electrode has a smaller Tafel slope which is only 67.2mV dec -1 Besides high-efficiency electrocatalytic hydrogen evolution performance, the catalyst also has excellent electrocatalytic hydrogen evolution stability.
(4) The preparation method is simple, the raw materials are easy to obtain, the reaction conditions are easy to achieve, the industrial large-scale production is easy to realize, and the preparation method has a good application prospect in the field of hydrogen energy.
Drawings
FIG. 1 shows NiCo from example 1 2 O 4 NF and Ni/Ni (OH) 2 -NiCo 2 O 4 SEM picture of/NF-1000;
FIG. 2 is the CoMoO of example 2 4 /NF and Ni/Ni (OH) 2 -CoMoO 4 SEM of/NF-1500;
FIG. 3 shows NiCo in example 1 2 O 4 /NF、Ni/Ni(OH) 2 -NiCo 2 O 4 /NF-1000 and Ni/Ni (OH) in example 3 2 Impedance plot of/NF-1000;
FIG. 4 shows NiCo in example 1 2 O 4 /NF、Ni/Ni(OH) 2 -NiCo 2 O 4 /NF-1000 and Ni/Ni (OH) in example 3 2 XRD pattern of/NF-1000;
FIG. 5 is an enlarged view of a portion of FIG. 4;
FIG. 6 is the CoMoO of example 2 4 /NF、Ni/Ni(OH) 2 -CoMoO 4 /NF-1500 and Ni/Ni (OH) in example 4 2 Impedance plot of/NF-1500;
FIG. 7 is a CoMoO of example 2 4 /NF、Ni/Ni(OH) 2 -CoMoO 4 NF-1500 andexample 4 Ni/Ni (OH) 2 XRD pattern of/NF-1500;
FIG. 8 is an enlarged view of a portion of FIG. 7;
FIG. 9 shows Ni/Ni (OH) in example 5 2 -CoMoO 4 The polarization curve of NF after 300-3000s electrodeposition time;
FIG. 10 shows NiCo from example 6 2 O 4 Polarization profile of NF after electrodeposition time of 100-3000 s.
Detailed Description
In order to make those skilled in the art fully understand the technical solutions and advantages of the present invention, the following description is further provided with reference to the specific embodiments and the accompanying drawings.
Example 1
Firstly, cutting a piece of foam nickel with the size of 3cm x 5cm, and then sequentially placing the foam nickel in HCl solution with the concentration of 1M, absolute ethyl alcohol and deionized water for ultrasonic cleaning for 15 minutes so as to remove oxides, oil stains and impurities on the surface of the foam nickel. And after the foamed nickel is cleaned, drying the foamed nickel for later use.
Mixing 2.2mmol of cobalt nitrate hexahydrate, 1.2mmol of nickel nitrate hexahydrate, 14mmol of urea and 80mL of deionized water, and performing ultrasonic dissolution to form a homogeneous solution to obtain a precursor solution for hydrothermal reaction. Adding the cleaned foam nickel and the precursor solution into a micro-reaction kettle with the capacity of 100mL, and then placing the micro-reaction kettle into an electric heating air blowing drying oven to react for 6 hours at the temperature of 120 ℃. And after the reaction is finished, taking out the foamed nickel, washing the foamed nickel for a plurality of times by using deionized water, and then freeze-drying the foamed nickel for 12 hours to finally obtain the Ni and Co bimetal hydroxide foamed nickel loaded with the one-dimensional nano array structure.
Heating the processed foamed nickel to 320 ℃ at the room temperature at the heating rate of 5 ℃/min in the air atmosphere, carrying out heat preservation annealing at the temperature for 2h, then cooling to the room temperature at the cooling rate of 5 ℃/min, and finally obtaining NiCo with the one-dimensional nano array structure 2 O 4 /NF。
Cutting a piece of NiCo with the size of 0.5cm x 0.5cm 2 O 4 and/NF is used as a working electrode, pt wires are used as a counter electrode, and a standard two-electrode electrodeposition system is built. Immersing the working electrode and the counter electrode in an electrolyteElectrodeposition was carried out at room temperature under constant current density. Wherein the electrolyte is an aqueous solution of nickel sulfamate and boric acid, and the concentrations of the nickel sulfamate and the boric acid in the solution are 1.02M and 50mM respectively; the current density is-52 mA/cm 2 The electrodeposition time was 1000s. Taking out the working electrode after the electrodeposition is finished, washing the working electrode for a plurality of times by deionized water, and freeze-drying the working electrode for 12 hours to finally obtain the hierarchical heterostructure Ni/Ni (OH) 2 -NiCo 2 O 4 /NF-1000。
NiCo obtained in this example 2 O 4 /NF、Ni/Ni(OH) 2 -NiCo 2 O 4 The SEM of/NF-1000 is shown in FIG. 1, in which a-c and d-f are NiCo with different multiples respectively 2 O 4 /NF and Ni/Ni (OH) 2 -NiCo 2 O 4 SEM picture of/NF-1000. As can be seen from FIG. 1, after two treatments, hydrothermal and high-temperature calcination, one-dimensional rod-like NiCo 2 O 4 Uniformly growing on the surface of the foamed nickel. After amplification, one-dimensional rod-like NiCo can be observed 2 O 4 The surface of (2) is very smooth and although it grows very densely on the surface of the nickel foam, there are large gaps between the rods. After electrodeposition, ni/Ni (OH) is formed 2 Uniformly growing on NiCo 2 O 4 On the nano-rod, the original one-dimensional nano-array appearance is not covered. Further amplifying the surface of the nano array can find that a layer of catalytic active substance grows on the surface of the original nano rod, so that NiCo 2 O 4 Becomes rougher, thereby increasing the contact area between the nano-array and the electrolyte.
Example 2
Firstly, cutting a piece of foam nickel with the size of 1cm x 2cm, then sequentially placing the foam nickel in ethanol, 1M HCl and deionized water for ultrasonic cleaning for 15 minutes, and taking out for later use.
The precursor liquid for hydrothermal reaction was prepared by referring to the method of example 1, in which the concentration of cobalt nitrate hexahydrate was 0.05M and the concentration of sodium molybdate tetrahydrate was 0.05M. Adding the treated foam nickel and 18mL of precursor liquid into a micro-reaction kettle with the capacity of 20mL, putting the micro-reaction kettle into an electric heating air blowing drying box, and heating to 160 ℃ for reaction for 4 hours. And after the reaction is finished and the reaction product is naturally cooled, taking out the foamed nickel, alternately washing the foamed nickel for a plurality of times by using deionized water and ethanol in sequence, and freeze-drying the foamed nickel for 12 hours.
Heating the foamed nickel obtained in the last step to 350 ℃ at room temperature at a heating rate of 5 ℃/min in the air atmosphere, carrying out heat preservation annealing at the temperature for 2h, cooling to room temperature at a cooling rate of 5 ℃/min, and finally obtaining the CoMoO with the one-dimensional nano array structure 4 /NF。
Cutting a piece of CoMoO with the size of 0.5cm x 0.5cm 4 and/NF is used as a working electrode, pt wires are used as a counter electrode, and a standard two-electrode electrodeposition system is built. The working electrode and the counter electrode were immersed in an electrolyte and electrodeposition was carried out at room temperature under constant current density. Wherein the electrolyte is an aqueous solution of nickel sulfamate and boric acid, and the concentrations of the nickel sulfamate and the boric acid in the solution are 1.02M and 50mM respectively; the current density is-52 mA/cm 2 The electrodeposition time was 1500s. Taking out the working electrode after the electrodeposition is finished, washing the working electrode for a plurality of times by deionized water, and freeze-drying the working electrode for 12 hours to finally obtain Ni/Ni (OH) 2 -CoMoO 4 /NF-1500。
CoMoO from example 2 4 /NF and Ni/Ni (OH) 2 -CoMoO 4 The SEM of/NF-1500 is shown in FIG. 2, wherein a-b and c-d are respectively CoMoO under different multiples 4 NF and Ni/Ni (OH) 2 -CoMoO 4 SEM picture of/NF-1500. As can be seen from FIG. 2, after two operations of hydrothermal method and high-temperature calcination, the two-dimensional CoMoO 4 The nano sheets vertically grow on the surface of the foam nickel, and form a mutually communicated net structure; the surface of the nano sheet is smoother and the sheet layer is thinner; the originally interconnected two-dimensional nanosheet structure is well maintained after electrodeposition, which indicates that the CoMoO is not damaged in the electrodeposition process 4 The morphology of (a); upon further magnification, the nanosheets were observed to significantly thicken after electrodeposition, indicating that Ni/Ni (OH) 2 Successful deposition on CoMoO 4 A surface.
Example 3
Firstly, cutting a piece of foamed nickel with the size of 0.5cm x 0.5cm, then sequentially placing the nickel in HCl with the concentration of 1M, absolute ethyl alcohol and deionized water for ultrasonic washing for 15 minutes, and taking out for later use.
And (3) taking foamed nickel as a working electrode and Pt wires as a counter electrode to build a standard two-electrode electrodeposition system. The working electrode and the counter electrode were immersed in an electrolyte and electrodeposition was carried out at room temperature under constant current density. Wherein the electrolyte is aqueous solution of nickel sulfamate and boric acid, and the concentrations of the nickel sulfamate and the boric acid are 1.02M and 50mM respectively; the current density is-52 mA/cm 2 The electrodeposition time was 1000s. Taking out the working electrode after the electrodeposition is finished, washing the working electrode for a plurality of times by deionized water, and freeze-drying the working electrode for 12 hours to finally obtain Ni/Ni (OH) 2 /NF-1000。
Electrochemical Impedance Spectroscopy (EIS) is mainly used for analyzing and testing the electrochemical impedance of a material, and is an important means for knowing the quality and the reason of the catalytic performance of the material. EIS testing was performed at open circuit potential ranging from 100kHz to 0.01Hz with an amplitude of 5mV. For NiCo obtained in example 1 2 O 4 /NF、Ni/Ni(OH) 2 -NiCo 2 O 4 /NF-1000 and Ni/Ni (OH) from example 3 2 The results of EIS testing of/NF-1000 are shown in FIG. 3. From FIG. 3, it can be found that Ni/Ni (OH) 2 -NiCo 2 O 4 Electron transfer resistance (R) of/NF-1000 ct ) Minimum, 6.2 Ω, indicating the fastest electron transfer rate; and NiCo 2 O 4 /NF and Ni/Ni (OH) 2 R of/NF-1000 ct Are all larger, 16.3 omega and 11.0 omega respectively.
For NiCo obtained in example 1 2 O 4 /NF、Ni/Ni(OH) 2 -NiCo 2 O 4 /NF-1000 and Ni/Ni (OH) from example 3 2 XRD analysis and test are carried out on the/NF-1000, and the results are shown in figures 4-5. As can be seen in FIGS. 4-5, niCo 2 O 4 Four weak signal peaks exist in the/NF, which are positioned at 31.7 degrees, 37.0 degrees, 59.2 degrees and 65.11 degrees and respectively correspond to NiCo 2 O 4 220, 311, 511 and 440 crystal planes (JCPDS No. 02-1074), which illustrate NiCo 2 O 4 Have been successfully grown on the surface of the nickel foam. Observe Ni/Ni (OH) in FIG. 5 2 -NiCo 2 O 4 Local delivery of/NF-1000The large XRD pattern revealed three weaker signals at 31.1 deg., 36.7 deg. and 44.0 deg., corresponding to NiCo, respectively 2 O 4 220, 311 and 400 (JCPDS No. 02-1074), which shows that after the second electrodeposition reaction, niCo is produced in the first step 2 O 4 The basic structure and the composition of the nano-rod are not changed. No Ni (OH) was found in the entire XRD pattern 2 The analysis may be due to Ni (OH) in three groups of samples 2 Is too low compared to the contents of the other substance components, resulting in its peak signal being masked.
Example 4
Firstly, cutting a piece of foam nickel with the size of 1cm x 2cm, then sequentially placing the foam nickel in ethanol, 1M HCl and deionized water for ultrasonic cleaning for 15 minutes, and taking out for later use.
And (3) taking foamed nickel as a working electrode and a Pt wire as a counter electrode to build a standard two-electrode electrodeposition system. And immersing the working electrode and the counter electrode into the electrolyte, and performing electrodeposition under the conditions of room temperature and constant current density. Wherein the electrolyte is aqueous solution of nickel sulfamate and boric acid, and the concentrations of the nickel sulfamate and the boric acid are 1.02M and 50mM respectively; the current density is-52 mA/cm 2 The electrodeposition time was 1500s. Taking out the working electrode after the electrodeposition is finished, washing the working electrode for a plurality of times by deionized water, and freeze-drying the working electrode for 12 hours to finally obtain Ni/Ni (OH) 2 /NF-1500。
FIG. 6 is a CoMoO of example 2 4 /NF、Ni/Ni(OH) 2 -CoMoO 4 /NF-1500 and Ni/Ni (OH) from example 4 2 EIS spectrum of/NF-1500. From FIG. 6, it can be found that Ni/Ni (OH) 2 -CoMoO 4 The electrochemical impedance of/NF is minimum, so the hydrogen evolution reaction kinetics is optimal, and the corresponding electrocatalytic hydrogen evolution performance is also optimal.
For the CoMoO prepared in example 2 4 /NF、Ni/Ni(OH) 2 -CoMoO 4 /NF-1500 and Ni/Ni (OH) from example 4 2 The results of XRD analysis of/NF-1500 are shown in FIGS. 7-8. As can be seen from FIGS. 7-8, ni/Ni (OH) 2 -CoMoO 4 /NF-1500、CoMoO 4 /NF and Ni/Ni (OH) 2 XR of/NF-1500There are only three distinct characteristic peaks in the spectrum D, located at 44.5 °, 51.85 ° and 76.4 °, corresponding to the 111, 200 and 220 crystal planes of metallic Ni (JCPDS No. 04-0850), respectively. CoMoO 4 /NF and Ni/Ni (OH) 2 -CoMoO 4 the/NF-1500 has three obvious diffraction peaks which are positioned at 26.5, 28.1 and 33.7 and respectively correspond to beta-CoMoO 4 The 002, -311 and-222 crystal planes (JCPDS No. 21-0868). This demonstrates our success with the CoMoO 4 CoMoO is loaded on the surface of foamed nickel and subjected to electrodeposition reaction 4 The composition and structure of the/NF were not changed. No Ni (OH) was observed in the XRD pattern 2 Probably due to Ni (OH) 2 Lower crystallinity or lower content.
Example 5
Firstly, cutting a piece of foam nickel with the size of 1cm x 2cm, then sequentially placing the foam nickel in ethanol, 1M HCl and deionized water for ultrasonic cleaning for 15 minutes, and taking out for later use.
The precursor liquid for hydrothermal reaction was prepared by referring to the method of example 1, in which the concentration of cobalt nitrate hexahydrate was 0.05M and the concentration of sodium molybdate tetrahydrate was 0.05M. Adding the treated nickel foam and 18mL of precursor liquid into a micro-reaction kettle with the capacity of 20mL, putting the micro-reaction kettle into an electric heating air blowing drying oven, and heating to 160 ℃ for reaction for 4 hours. And naturally cooling after the reaction, taking out the foamed nickel, alternately washing the foamed nickel for a plurality of times by using deionized water and ethanol, and then freeze-drying the foamed nickel for 12 hours.
Heating the foamed nickel obtained in the last step to 350 ℃ at the temperature rise rate of 5 ℃/min in the air atmosphere, carrying out heat preservation annealing at the temperature for 2h, then cooling to room temperature at the temperature drop rate of 5 ℃/min, and finally obtaining the CoMoO with the two-dimensional nanosheet array structure 4 /NF。
Cutting a piece of CoMoO with the size of 0.5cm x 0.5cm 4 and/NF is used as a working electrode, pt wires are used as a counter electrode, and a standard two-electrode electrodeposition system is built. The working electrode and the counter electrode were immersed in an electrolyte and electrodeposition was carried out at room temperature under constant current density. Wherein the electrolyte is aqueous solution of nickel sulfamate and boric acid, the pH value is adjusted to 4.0 by using sulfuric acid, and the concentrations of the nickel sulfamate and the boric acid in the electrolyte are respectively1.02M, 50mM, current density-52 mA/cm 2 The electrodeposition time was 100s, 300s, 500s, 1000s, 1500s, 2000s and 3000s, respectively. Taking out the working electrode after the electrodeposition is finished, washing the working electrode for a plurality of times by deionized water, and freeze-drying the working electrode for 12 hours to finally obtain a series of catalyst materials which are respectively marked as Ni/Ni (OH) 2 -CoMoO 4 /NF-100、Ni/Ni(OH) 2 -CoMoO 4 /NF-300、Ni/Ni(OH) 2 -CoMoO 4 /NF-500、Ni/Ni(OH) 2 -CoMoO 4 /NF-1000、Ni/Ni(OH) 2 -CoMoO 4 /NF-1500、Ni/Ni(OH) 2 -CoMoO 4 /NF-2000 and Ni/Ni (OH) 2 -CoMoO 4 /NF-3000。
FIG. 9 shows a series of Ni/Ni (OH) samples obtained in this example 2 -CoMoO 4 Polarization plot of/NF. As can be seen from the figure, at a low current density of 10mA/cm 2 And a high current density of 100mA/cm 2 The overpotential of the catalyst has the same trend along with the change of the electrodeposition time; when the electrodeposition time is increased from 0s to 1500s, the overpotential is reduced along with the increase of the electrodeposition time; when the electrodeposition time is increased from 1500s to 3000s, the overpotential increases with the increase of the electrodeposition time.
The test also found that Ni/Ni (OH) 2 -CoMoO 4 the/NF-1500 sample exhibited excellent electrocatalytic hydrogen evolution performance in a KOH aqueous solution at a concentration of 1M. When the current density is 10, 20 and 100mA/cm 2 The overpotential is 86mV, 122mV, 207mV, respectively.
Example 6
Firstly, cutting a piece of foam nickel with the size of 3cm x 5cm, then sequentially placing the foam nickel in HCl with the concentration of 1M, absolute ethyl alcohol and deionized water for ultrasonic cleaning for 15 minutes, and taking out for later use.
2.2mmol of cobalt nitrate hexahydrate, 1.2mmol of nickel nitrate hexahydrate and 14mmol of urea are ultrasonically dissolved in 80mL of deionized water to form a homogeneous solution, and a precursor solution of the hydrothermal reaction is obtained. Adding the cleaned nickel foam and 80mL of precursor liquid into a micro-reaction kettle with the capacity of 100mL, then placing the micro-reaction kettle into an electric heating air blowing drying oven, and heating to 120 ℃ for reaction for 6 hours. And naturally cooling after the reaction, taking out the foamed nickel, washing the foamed nickel for a plurality of times by using deionized water, and freeze-drying for 12 hours to finally obtain the foamed nickel loaded with the Ni and Co bimetal hydroxide with the one-dimensional nano array structure.
Heating the foamed nickel obtained in the last step to 320 ℃ at the temperature rise rate of 5 ℃/min in the air atmosphere, carrying out heat preservation annealing at the temperature for 2h, then cooling to room temperature at the temperature drop rate of 5 ℃/min, and finally obtaining NiCo with a one-dimensional nano array structure 2 O 4 /NF。
Cutting a piece of NiCo with the size of 0.5cm x 0.5cm 2 O 4 and/NF is used as a working electrode, pt wires are used as a counter electrode, and a standard two-electrode electrodeposition system is built. The working electrode and the counter electrode were immersed in an electrolyte and electrodeposition was carried out at room temperature under constant current density. Wherein the electrolyte is aqueous solution of nickel sulfamate and boric acid, the concentrations of nickel sulfamate and boric acid are 1.02M and 50mM respectively, and the current density is-52 mA/cm 2 The electrodeposition time was 100s, 300s, 500s, 1000s, 1500s and 3000s, respectively. Taking out the working electrode after the electrodeposition is finished, washing the working electrode for a plurality of times by deionized water, and freeze-drying the working electrode for 12 hours to finally obtain the catalysts which are respectively marked as Ni/Ni (OH) 2 -NiCo 2 O 4 /NF-100、Ni/Ni(OH) 2 -NiCo 2 O 4 /NF-300、Ni/Ni(OH) 2 -NiCo 2 O 4 /NF-500、Ni/Ni(OH) 2 -NiCo 2 O 4 /NF-1000、Ni/Ni(OH) 2 -NiCo 2 O 4 /NF-1500 and Ni/Ni (OH) 2 -NiCo 2 O 4 /NF-3000。
FIG. 10 is a plot of the polarization of a series of catalyst materials prepared in example 6. As can be seen from FIG. 10, when the electrodeposition time is 1000s, ni/Ni (OH) 2 -NiCo 2 O 4 The overpotential of the/NF-1000 under each current density is the minimum, and the corresponding hydrogen evolution performance of the electrolyzed water is the highest; when the electrodeposition time is increased from 0s to 1000s, the overpotential is reduced along with the increase of the time; when the electrodeposition time is increased from 1000s to 3000s, the overpotential increases first and then substantially levels off.
For Ni/Ni (OH) 2 -NiCo 2 O 4 In the case of/NF-1000, it exhibits excellent catalysis in an aqueous KOH solution having a concentration of 1MAnd (4) performance is improved. When the current density is 10, 20, 100mA/cm 2 When in use, the overpotential is respectively 60mV, 96 mV and 187mV, which are obviously superior to Ni/Ni (OH) 2 -CoMoO 4 NF-1500 and some similar catalytic materials reported in recent literature.

Claims (10)

1. Ni/Ni (OH) with hierarchical heterostructure 2 -NiCo 2 O 4 The preparation method of the/MF catalytic electrode is characterized by comprising the following steps: (a) Dissolving cobalt salt, nickel salt and urea in water to obtain a precursor liquid; (b) Adding the foam metal into the precursor liquid for hydrothermal reaction to obtain Ni and Co bimetal hydroxide foam metal loaded with a one-dimensional nano array structure; (c) Carrying out heat treatment on the product prepared in the step (b) to obtain NiCo with a one-dimensional nano array structure 2 O 4 /MF; (d) With NiCo 2 O 4 the/MF is used as a working electrode, and a hierarchical heterostructure Ni/Ni (OH) is prepared by means of electrodeposition 2 -NiCo 2 O 4 a/MF catalytic electrode.
2. The method of claim 1, wherein: the cobalt salt in the step (a) is at least one selected from cobalt sulfate, cobalt nitrate, cobalt acetate, cobalt chloride or hydrate thereof, and the nickel salt is at least one selected from nickel chloride, nickel nitrate or hydrate thereof.
3. The method of claim 1, wherein: in the step (a), the molar ratio of the cobalt salt to the nickel salt to the urea is 3-2.
4. The method of claim 1, wherein: the foam metal in the step (b) is selected from one of foam nickel, foam copper, foam iron and foam zinc, and the foam metal needs acid washing, alcohol washing and water washing before use.
5. The method of claim 1, wherein: the hydrothermal reaction temperature in the step (b) is 100-200 ℃, and the heat preservation time is 2-8h.
6. The method of claim 1, wherein: the heat treatment temperature in the step (c) is 300-500 ℃, the heat treatment time is 100-200min, the heating rate and the cooling rate are both 4-8 ℃/min, and the heat treatment atmosphere is air atmosphere.
7. The method of claim 1, wherein step (d) is performed as follows: with NiCo 2 O 4 The method comprises the following steps of (1) taking/MF as a working electrode and Pt wires as a counter electrode, and building a standard two-electrode electrodeposition system; and (3) inserting the two electrodes into the electrolyte for electrodeposition, and finally taking out, cleaning and drying.
8. The method of claim 7, wherein: the electrolyte is a mixture of nickel sulfamate, boric acid and deionized water, and an acid reagent is added to adjust the pH of the electrolyte to 3.0-5.0 in the electrodeposition process; the molar ratio of the nickel sulfamate to the boric acid in the electrolyte is 20-30; the electrodeposition temperature is normal temperature, the electrodeposition time is 100-3000s, the electrodeposition mode is constant current density, and the current density is controlled at-60 mA/cm 2 To-40 mA/cm 2 。
9. Ni/Ni (OH) with hierarchical heterostructure 2 -NiCo 2 O 4 the/MF catalytic electrode is characterized in that: the catalytic electrode is prepared according to any one of the methods of claims 1-8.
10. The Ni/Ni (OH) with hierarchical heterostructure of claim 9 2 -NiCo 2 O 4 The application of the/MF catalytic electrode in the aspect of electrocatalytic hydrogen evolution.
CN202211212020.6A 2022-09-30 2022-09-30 Ni/Ni (OH) with hierarchical heterostructures 2 -NiCo 2 O 4 /MF catalytic electrode Pending CN115505959A (en)

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