Preparation and use of nickel-foam-supported layered cobalt tungsten oxide catalyst for efficient water decomposition

Abstract

The present invention belongs to the technical field of electrochemical catalysis. Disclosed are the preparation and use of a nickel-foam-supported layered cobalt tungsten oxide catalyst for efficient water decomposition. In the present invention, nickel foam (NF) is selected as a substrate, on which two cobalt oxides having different morphologies successively grow by means of electrochemical deposition, wherein ComCo3O4 serves as a first layer and can tightly wrap around the NF, thereby preventing the NF from anodic corrosion and dissolution in a harsh acidic medium; AcCo3O4 serves as a second layer, and nanosheet-shaped Co3O4 has good OER activity itself; in addition, the large specific surface area also provides more growth sites for a tungsten oxide; and finally, the tungsten oxide is electrically deposited on the AcCo3O4. WxOy / AcCo3O4 / ComCo3O4 / NF prepared by using the above method has a low overpotential and good stability.

Description

Preparation and application of foam nickel layered cobalt tungsten oxide catalyst for efficient water decomposition TECHNICAL FIELD

[0001] The present application belongs to the technical field of electrochemical catalysis, and more particularly relates to a preparation and application of a foam nickel layered cobalt tungsten oxide catalyst for efficient water decomposition. BACKGROUND

[0002] Hydrogen energy has a high calorific value, which is more than three times that of oil, is an ideal fossil fuel substitute, and hydrogen combustion does not produce any harmful or greenhouse gases after use. Electrolysis of water by electrocatalysis is one of the most promising strategies to meet future energy needs of mankind. Among different water electrolysis oxygen evolution reaction hydrogen production technologies, proton exchange membrane water electrolysis has advantages in productivity, energy stability, and cost compared with other hydrogen production technologies. However, there are still great challenges in the sustainable large-scale production of hydrogen by proton exchange membrane, that is, there is no stable and inexpensive OER (oxygen evolution reaction) catalyst that can work at high current density. Noble metal-based catalysts such as Ru-based and Ir-based catalysts exhibit good stability and activity, but they still suffer from metal dissolution in the acidic medium inherent to the lattice oxygen evolution reaction mechanism. Therefore, it is urgent to develop an effective and stable noble metal-free anode oxygen evolution catalyst for proton exchange membranes.

[0003] Various 3d transition metal oxides and their derivatives have the advantages of high abundance and low cost, and have received extensive attention as OER candidates. Among them, cobalt-based oxides have good OER activity in acidic medium, and the OER of cobalt-based oxides is considered to be one of the most promising OER candidates. According to theoretical calculations, the OER activity of cobalt-based oxides should be comparable to that of ruthenium-based and iridium-based oxides. However, Co3O4 exhibits high overpotential and instability under harsh OER conditions, especially in acidic medium at high oxidation potential. This expected activity is challenged by the limited stability of cobalt oxides in acid. How to prepare a cobalt-based anode oxygen evolution catalyst with high activity and high stability is still a great challenge. SUMMARY

[0004] The purpose of the present application is to provide a preparation and application of a foam nickel layered cobalt tungsten oxide catalyst for efficient water decomposition to solve the problems existing in the prior art and realize the preparation of a cobalt-based anode oxygen evolution catalyst with high activity and high stability.

[0005] To achieve the above purpose, the present application provides the following solutions:

[0006] One of the technical solutions of the present application: a preparation method of a foam nickel layered cobalt tungsten oxide catalyst for efficient water decomposition is provided, comprising the following steps:

[0007] S1, sequentially performing electrochemical deposition treatment on the foamed nickel with a cobalt source and boric acid as an electroplating solution, oxidation with potassium hydroxide solution as an electroplating solution, and calcination to obtain ComCo3O4 / NF;

[0008] S2, sequentially performing electrochemical deposition treatment on the ComCo3O4 / NF with a cobalt source and polyvinylpyrrolidone as an electroplating solution, and calcination to obtain AcCo3O4 / ComCo3O4 / NF;

[0009] S3, sequentially performing electrochemical deposition treatment on the AcCo3O4 / ComCo3O4 / NF with a tungsten source as an electroplating solution, and calcination to obtain the foamed nickel layered cobalt-tungsten oxide catalyst for efficient water splitting, denoted as W x O y / AcCo3O4 / ComCo3O4 / NF.

[0010] The "W x O y " in the present application represents tungsten oxide, wherein x and y are the atomic ratio of tungsten and oxygen, including: WO3 (tungsten trioxide), W2O5 (tungsten pentoxide), etc.

[0011] Preferably, in step S1, the electroplating solution is added in the form of an aqueous solution; in the electroplating solution, the concentration of the cobalt source is 0.1-0.2 mol / L, and the concentration of the acid reagent is 0.5-0.7 mol / L; the acid reagent includes boric acid and / or oxalic acid.

[0012] In step S1, the acid reagent functions to adjust the pH of the electroplating solution, and the potassium hydroxide solution functions to provide an alkaline environment, so that the electrode sheet surface obtained by performing electrochemical deposition treatment in step S1 can be oxidized into cobalt hydroxide.

[0013] Preferably, in step S1, the deposition current of the electrochemical deposition treatment is 15-20 mA, and the deposition time is 60-90 min; the concentration of the potassium hydroxide solution is 0.5-1 mol / L, and the current of the oxidation is 3-6 mA; the heating rate of the calcination is 5 ℃ / min, the temperature is 500 ℃, and the holding time is 3-5 h.

[0014] Preferably, in step S2, the cobalt source includes cobalt nitrate and / or cobalt sulfate; the electroplating solution is added in the form of an aqueous solution; in the electroplating solution, the concentration of the cobalt source is 0.05-0.1 mol / L, and the concentration of the polyvinylpyrrolidone is 1-2 g / L.

[0015] In step S2, the polyvinylpyrrolidone functions as a surfactant, which can cause the deposition of cobalt ions from the solution in the form of nanosheet-shaped cobalt compounds.

[0016] Preferably, in step S2, the deposition current of the electrochemical deposition treatment is 3-6 mA, and the deposition time is 30-45 min; the heating rate of the calcination is 5 DEG C / min, the temperature is 350 DEG C, and the holding time is 3-5 h.

[0017] Preferably, in step S3, the tungsten source comprises sodium tungstate and / or potassium tungstate; the electroplating solution is in the form of an aqueous solution; and in the electroplating solution, the concentration of sodium tungstate is 0.1-0.5 mol / L.

[0018] Preferably, in step S3, the deposition current of the electrochemical deposition treatment is 10-15 mA, and the deposition time is 20-30 min; the heating rate of the calcination is 5 DEG C / min, the temperature is 350 DEG C, and the holding time is 3-5 h.

[0019] The second technical scheme of the present application provides the foam nickel layered cobalt-tungsten oxide catalyst for efficient water decomposition prepared by the preparation method.

[0020] The third technical scheme of the present application provides the application of the foam nickel layered cobalt-tungsten oxide catalyst for efficient water decomposition in electrolytic water hydrogen production.

[0021] The fourth technical scheme of the present application provides a method for improving the electrolytic water hydrogen production effect and stability, comprising the following steps:

[0022] The foam nickel layered cobalt-tungsten oxide catalyst for efficient water decomposition is used as a working electrode, a platinum sheet is used as a counter electrode, a saturated mercury-mercury electrode is used as a reference electrode, and a 0.5 mol / L H2SO4 solution is used as an electrolyte, so that the electrolytic water reaction is carried out in a three-electrode system.

[0023] The technical principle of the present application is as follows:

[0024] The present application selects foam nickel (NF) as a substrate, grows two kinds of cobalt oxides with different morphologies through electrochemical deposition, wherein ComCo3O4 is the first layer, can tightly wrap the NF, and makes the NF not be anodically corroded and dissolved in a harsh acidic medium, AcCo3O4 is the second layer, the nanosheet-shaped Co3O4 itself has good OER activity, in addition, the larger specific surface area also provides more growth sites for tungsten oxide, and finally, tungsten oxide is electro-deposited on the AcCo3O4, so that the W x O y / AcCo3O4 / ComCo3O4 / NF has a lower overpotential and good stability.

[0025] The present application discloses the following technical effects:

[0026] 1. The catalyst preparation method described in this invention employs a simple process combining electrochemical deposition and calcination, requiring no complex equipment or harsh reaction conditions. First, the target material is uniformly deposited onto the substrate surface using electrochemical deposition under mild reaction conditions, relying solely on electrical energy. Subsequently, it is placed in a conventional muffle furnace for calcination. The entire process is simple and easy to understand, with readily available raw materials, requiring no lengthy operation by specialized technicians, significantly lowering the preparation threshold and demonstrating high feasibility and practicality.

[0027] 2. The catalyst of this invention innovatively employs a multi-layered composite structure design, cleverly integrating cobalt oxides of different morphologies to construct a synergistic microscopic system. The dense cobalt tetroxide protects the nickel foam substrate from anodic corrosion and damage to the overall material structure. The three-dimensional, interwoven arrangement of nanosheet-like cobalt tetroxide creates abundant space, providing ideal growth sites and attachment spaces for the subsequent growth of tungsten oxides. Through this design, the quality and quantity of active sites in the material are optimized, ensuring the catalytic efficiency of individual active sites while expanding the reaction area by increasing the number of sites, ultimately achieving a comprehensive improvement in performance.

[0028] 3. The catalyst of this invention uses transition elements that are abundant and inexpensive in the Earth's crust as raw materials, and the catalyst operates at 10 mA / cm². 2 At a current density of only 266mV, the catalyst exhibits an ultra-low overpotential of just 266mV, significantly outperforming most similar non-precious metal materials. Constant current testing verified that the catalyst maintained its structural integrity and catalytic activity even after continuous operation in strong acid for over 12 hours, demonstrating excellent corrosion resistance and anti-degradation performance. Through lower raw material costs and optimized energy consumption, the cost of hydrogen production via water electrolysis is effectively reduced. Attached Figure Description

[0029] Figure 1 shows the ComCo3O4 / NF, AcCo3O4 / ComCo3O4 / NF, and W obtained in Example 1. x O y XRD pattern of / AcCo3O4 / ComCo3O4 / NF;

[0030] Figure 2 shows the ComCo3O4 / NF, AcCo3O4 / ComCo3O4 / NF, and W obtained in Example 1. x O y Nitrogen isothermal adsorption-desorption curves and specific surface area results for / AcCo3O4 / ComCo3O4 / NF;

[0031] Figure 3 shows the ComCo3O4 / NF, AcCo3O4 / ComCo3O4 / NF, and W obtained in Example 1. x O ySEM images of / AcCo3O4 / ComCo3O4 / NF, wherein a is ComCo3O4 / NF, b is AcCo3O4 / ComCo3O4 / NF, c is W x O y SEM images of / AcCo3O4 / ComCo3O4 / NF, wherein a is ComCo3O4 / NF, b is AcCo3O4 / ComCo3O4 / NF, c is W x O y SEM images of / AcCo3O4 / ComCo3O4 / NF, wherein a is ComCo3O4 / NF, b is AcCo3O4 / ComCo3O4 / NF, c is W

[0032] Figure 4 is the W x O y Raman spectra and X-ray photoelectron spectroscopy of / AcCo3O4 / ComCo3O4 / NF;

[0033] Figure 5 is the electrochemical active surface area (ECSA) test results of the nickel foam loaded with different cobalt-tungsten oxides;

[0034] Figure 6 is the electrochemical impedance spectroscopy (EIS) test results of the nickel foam materials loaded with different cobalt-tungsten oxides in different orders;

[0035] Figure 7 is the linear voltammetry curves of the nickel foam loaded with different cobalt-tungsten oxide materials and the test results of their stability in acidic medium. DETAILED DESCRIPTION

[0036] The following detailed description is presented to provide a thorough understanding of certain aspects of the application. However, the description is not intended to be exhaustive, and it is not intended to be limiting to the present application. The description is presented for the purpose of describing certain embodiments of the application, and is not intended to limit the application to the embodiments described.

[0037] It should be understood that the terms used herein are merely descriptive, but are not intended to be limiting to the present application. In addition, for numerical ranges described herein, it is to be understood that every numerical value between the upper and lower limits of the range is specifically contemplated. Each smaller range between any of the above-mentioned numerical values or between any other stated numerical values in the above-mentioned ranges is also contemplated. The upper and lower limits of these smaller ranges can independently be included or excluded in the ranges.

[0038] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict between the content of the specification and that of any document incorporated herein by reference, the content of the specification prevails.

[0039] Many modifications and variations to the illustrative embodiments described herein will be apparent to those of ordinary skill in the art from the foregoing detailed description of the application. Such variations may not depart from the scope of the application. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only. It is to be understood that the application is not limited in any way by the specific details of the application described herein.

[0040] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended terms that are intended to mean "including but not limited to".

[0041] It should be noted that the present application does not describe in detail the conventional operation means in the art, and is not the focus of the present application.

[0042] The raw materials used in the following examples and comparative examples of the present application are commercially available unless otherwise specified, and the source of the commercially available products does not affect the technical effects of the present application.

[0043] The foamed nickel used in the present application is purchased from Kunshan Changpu Town Baiyida Electronic New Material Business Department.

[0044] Example 1

[0045] The present embodiment provides a preparation method of a foamed nickel layered cobalt-tungsten oxide catalyst, and the steps are as follows:

[0046] (1) Preparation of ComCo3O4 / NF

[0047] a. Dissolve 40 g of Co(NO3)2·6H2O and 40 g of H3BO3 in 1 L of deionized water to obtain an electroplating solution, take out 30 mL in a beaker, then use foamed nickel with an area of 1x2 cm 2 as the working electrode, carbon sheet with an area of 1x2 cm 2 as the counter electrode, and deposit for 60 min under the condition of a deposition current of 15 mA, and then naturally air dry after completion.

[0048] b. Use the electrode sheet as the working electrode, and use carbon sheet with an area of 1x2 cm 2 as the counter electrode, and completely oxidize in 1 mol / L potassium hydroxide solution, with an oxidation current of 3 mA, and the oxidation time is 60 min.

[0049] c. Place the obtained electrode sheet in a muffle furnace and heat to 500℃ at a heating rate of 5℃ / min, and calcine for 3 h to prepare ComCo3O4 / NF.

[0050] (2) Preparation of AcCo3O4 / ComCo3O4 / NF

[0051] a. 28 g of Co(N03)2-6H20 and 1 g of polyvinylpyrrolidone (PVP) were dissolved in 1 L of deionized water to obtain an electroplating solution, and 30 mL was taken in a beaker. ComCo304 / NF was used as the working electrode, and a carbon sheet with an area of 1 x 2 cm was used as the counter electrode. Deposition was carried out in the electroplating solution for 30 min at a deposition current of 3 mA. 2

[0052] b. The obtained electrode sheet was placed in a muffle furnace and calcined at 350°C for 3 h at a temperature increase rate of 5°C / min to prepare AcCo304 / ComCo304 / NF.

[0053] (3) WO4 / AcCo304 / ComCo304 / NF was prepared x y WO4 / AcCo304 / ComCo304 / NF was prepared

[0054] a. The electroplating solution was a 0.1 mol / L sodium tungstate solution, and 30 mL was taken in a beaker. AcCo304 / ComCo304 / NF was used as the working electrode, and a carbon sheet with an area of 1 x 2 cm was used as the counter electrode. Deposition was carried out in the electroplating solution for 20 min at a deposition current of 10 mA. 2

[0055] b. The obtained electrode sheet was placed in a muffle furnace and calcined at 350°C for 3 h at a temperature increase rate of 5°C / min to prepare WO4 / AcCo304 / ComCo304 / NF. x y WO4 / AcCo304 / ComCo304 / NF was prepared

[0056] Comparative Example 1 (changing the deposition order of cobalt tungsten oxide)

[0057] (1) WO4 / ComCo304 / NF was prepared x y WO4 / ComCo304 / NF was prepared

[0058] a. ComCo304 / NF prepared in Example 1 was used as the working electrode, and a carbon sheet was used as the counter electrode. The electroplating solution was a 0.1 mol / L sodium tungstate solution, and 30 mL was taken in a beaker. Deposition was carried out in the electroplating solution for 20 min at a deposition current of 10 mA.

[0059] b. The obtained electrode sheet was placed in a muffle furnace and calcined at 350°C for 3 h at a temperature increase rate of 5°C / min to prepare WO4 / ComCo304 / NF. x y WO4 / ComCo304 / NF was prepared

[0060] Comparative Example 2

[0061] (1) AcCo304 / WO4 was prepared x y ​​​​​​​Preparation of / ComCo3O4 / NF

[0062] a. W prepared in Comparative Example 1 x O y / ComCo3O4 / NF as the working electrode and carbon sheet as the counter electrode, 28 g of Co(N03)2·6H2O and 1 g of polyvinylpyrrolidone (PVP) were dissolved in 1 L of deionized water to obtain an electroplating solution, 30 mL of which was taken out in a beaker and deposited in the electroplating solution for 20 min at a deposition current of 3 mA.

[0063] b. The obtained electrode sheet was placed in a muffle furnace and calcined at 350℃ for 3 h at a heating rate of 5℃ / min to prepare AcCo3O4 / W x O y / ComCo3O4 / NF.

[0064] Example 1, AcCo3O4 / ComCo3O4 / NF, W x O y / AcCo3O4 / ComCo3O4 / NF.

[0065] Figure 1 is an XRD pattern of ComCo3O4 / NF, AcCo3O4 / ComCo3O4 / NF, W x O y / AcCo3O4 / ComCo3O4 / NF obtained in Example 1.

[0066] From the analysis of the XRD spectrum in Figure 1, it can be seen that ComCo3O4 / NF, AcCo3O4 / ComCo3O4 / NF, W x O y / AcCo3O4 / ComCo3O4 / NF all show characteristic diffraction peaks consistent with the standard cards of Ni and Co3O4. The characteristic peaks appearing at 2θ of 44.5°, 51.8° and 76.4° correspond to the crystal structure of nickel foam (NF); while the diffraction peaks at 2θ of 31°, 36.8°, 59.6° and 65.2° clearly indicate the presence of cobalt trioxide (Co3O4) component in the sample. It is worth noting that although the sample contains tungsten oxide (W x O y ) obtained by electrochemical deposition, no characteristic diffraction peaks matching it appear in the spectrum. Through analysis, this is because the tungsten oxide prepared by electrochemical deposition is in amorphous state, lacking long-range ordered crystal structure, so it cannot produce obvious crystal diffraction signals.

[0067] Figure 2 is a TEM image of ComCo3O4 / NF, AcCo3O4 / ComCo3O4 / NF, Wx O y Nitrogen adsorption-desorption curves and specific surface area results of ComCo3O4 / NF, AcCo3O4 / ComCo3O4 / NF and W

[0068] From the nitrogen adsorption curve analysis of Figure 2, it can be seen that the ComCo3O4 / NF, AcCo3O4 / ComCo3O4 / NF, W x O y Among the three materials of ComCo3O4 / NF, AcCo3O4 / ComCo3O4 / NF and W x O y The sample of AcCo3O4 / ComCo3O4 / NF presents the most significant adsorption performance, and the specific surface area value is the largest. This phenomenon can be attributed to the synergistic effect of structural optimization: the nanosheet-shaped AcCo3O4 grown on the ComCo3O4 layer significantly expands the active sites of the material surface due to its unique two-dimensional morphology; at the same time, this nanosheet structure provides abundant nucleation and growth space for the subsequent deposition of tungsten oxide, promoting the formation of W x O y The uniform dispersion of AcCo3O4 on the surface further increases the pore structure and specific surface area of the material, which is highly consistent with the experimental data reflected in the nitrogen adsorption curve.

[0069] Figure 3 is a SEM image of ComCo3O4 / NF, AcCo3O4 / ComCo3O4 / NF, W x O y / AcCo3O4 / ComCo3O4 / NF, where a is ComCo3O4 / NF, b is AcCo3O4 / ComCo3O4 / NF, c is W x O y / AcCo3O4 / ComCo3O4 / NF, d is W x O y / AcCo3O4 / ComCo3O4 / NF.

[0070] From Figure 3a, it can be clearly observed that ComCo3O4 covers the surface of the foam nickel (NF) substrate in the form of a uniform continuous film layer. This close coating structure can effectively isolate the direct contact of the electrolyte with the NF, thereby significantly inhibiting the anode corrosion and dissolution of the substrate. In Figure 3b, a large number of nanosheet-shaped AcCo3O4 grow vertically on the surface of ComCo3O4. Its unique two-dimensional morphology not only significantly increases the specific surface area of the material, but also provides abundant active sites for subsequent deposition reactions. It is worth noting that the presence of tungsten oxide (W x O y ) cannot be directly observed in Figure 3c, which is due to the Wx O y Due to the low loading amount and extremely small size, the d of Figure 3 further confirms the high protection effect of ComCo304 on NF - the ComCo304 layer closely adheres to the NF substrate, with almost no gap. In addition, the ordered growth of AcCo304 nanosheets on the ComCo304 layer directly verifies that the nickel foam successfully realizes the hierarchical loading of cobalt-tungsten oxides, providing a structural basis for the optimization of material performance.

[0071] Figure 4 is the Raman spectrum of the W x O y / AcCo3O4 / ComCo3O4 / NF material obtained in Example 1.

[0072] Figure 4 presents the Raman spectrum and X-ray photoelectron spectroscopy (XPS) characterization data of the W x O y / AcCo3O4 / ComCo3O4 / NF material. Raman spectrum analysis shows that characteristic peaks appear at 190.6 cm -1 , 470.4 cm -1 , 511.5 cm -1 and 669.0 cm -1 , which are highly consistent with the standard spectrum of cobalt trioxide (Co3O4); while the vibration peak at 879.5 cm -1 corresponds to the stretching vibration of W-O bond, which directly reflects the presence of tungsten oxide. Further XPS characterization found characteristic peaks at binding energies of 36.9 eV and 34.7 eV, which are attributed to the spin-orbit splitting peaks of W4f orbitals, which provides direct evidence for the valence state and existence form of tungsten elements in the material. The Raman spectrum and XPS characterization results confirm each other, and clearly show that the nickel foam substrate has successfully realized the loading of cobalt-tungsten oxides, verifying the composition and structural design of the material from the molecular vibration and electronic structure level.

[0073] Electrochemical performance analysis of the products obtained in the above examples and comparative examples:

[0074] Using the products obtained in the above examples and comparative examples as the working electrode, saturated calomel as the reference electrode, and a platinum sheet with an area of 1 x 1 cm 2 as the counter electrode, the electrochemical performance of the products was tested in a three-electrode system in a 0.5 mol / L H2SO4 solution.

[0075] Figure 5 is the electrochemical active surface area (ECSA) test results of the nickel foam loaded with different cobalt-tungsten oxides.

[0076] Figure 5 shows that the W x O y / AcCo3O4 / ComCo3O4 / NF exhibits the highest electrochemically active area, meaning it possesses a larger electrochemically activated surface region, effectively exposing more catalytically active sites. This superior performance can be attributed to a dual mechanism: firstly, the nanosheet structure of AcCo3O4 provides W... x O y The growth site provides ideal growth sites, significantly increasing the contact area between the material and the electrolyte; secondly, W x O y Both possess excellent intrinsic electrocatalytic activity, and their synergistic effect further enhances the overall performance of the material. Furthermore, by comparing the material performance under different loading orders, it can be seen that only when W... x O y The catalytic performance can only be maximized when grown on the surface of cobalt nanosheets AcCo3O4, while W x O y Directly loaded onto the ComCo3O4 layer, or first deposited W x O y The regenerated AcCo3O4 structure could not fully realize its catalytic potential.

[0077] Figure 6 shows the electrochemical impedance spectroscopy (EIS) results of nickel foam materials with different cobalt tungsten oxide loading sequences.

[0078] Figure 6 shows that W x O y The / AcCo3O4 / ComCo3O4 / NF structure exhibits the lowest charge transfer impedance, indicating the fastest charge migration rate in electrochemical reactions. Notably, the overall impedance of the system significantly decreases after introducing tungsten oxide onto ComCo3O4 / NF, validating that layered loading of cobalt-tungsten oxide effectively optimizes the electron transport path. EIS results directly confirm from a kinetic perspective that constructing a cobalt-tungsten oxide composite structure layer-by-layer on the nickel foam surface not only reduces interfacial resistance but also significantly enhances the electrochemical activity of the material, providing strong experimental evidence for the feasibility of this preparation method.

[0079] Figure 7 shows the linear current-voltage curves of nickel foam loaded with different cobalt-tungsten oxide materials and their stability test results in acidic media.

[0080] Figure 7 shows that ComCo3O4 / NF can be stably operated for 12 h in an acidic environment, exhibiting good basic stability. After growing cobalt nanosheets (AcCo3O4) on the surface of ComCo3O4 / NF, the oxygen evolution reaction (OER) overpotential is significantly reduced, and the material stability is further improved. In contrast, when directly loading tungsten oxide on ComCo3O4 / NF, the performance improvement effect is relatively limited, which is mainly due to the low specific surface area characteristics of ComCo3O4 / NF, which is difficult to provide sufficient active sites to support the effective growth of tungsten oxide. The W x O y / AcCo3O4 / ComCo3O4 / NF composite structure formed by depositing tungsten oxide on the surface of cobalt nanosheets, with its unique layered architecture and synergistic effect, not only significantly reduces the OER overpotential, but also significantly improves the long-term stability of the material in acidic medium, fully demonstrating the significant advantages of the layered loading strategy in optimizing the electrocatalytic performance.

[0081] The effect of loading cobalt-tungsten oxide on foam nickel on the electrochemical performance of the foam nickel was verified, and the results are shown in Table 1:

[0082] Table 1

[0083] Table 1 compares the effect of different loading sequences of cobalt-tungsten oxide on foam nickel on the performance of the material. The experimental results show that the loading sequence has a significant effect on the electrochemical performance of the material: directly depositing tungsten oxide on ComCo3O4 / NF is difficult to provide sufficient active sites due to the limited specific surface area of ComCo3O4 / NF, resulting in poor performance improvement effect; while growing cobalt nanosheets (AcCo3O4) on ComCo3O4 / NF to form a three-dimensional porous structure, and then depositing tungsten oxide (W x O y ), can fully exert the catalytic performance of the material. The W x O y / AcCo3O4 / ComCo3O4 / NF composite material catalyst prepared under this strategy exhibits an ultra-low overpotential of only 265 mV at a current density of 10 mA / cm 2 , which is significantly better than most similar non-noble metal materials. The constant current test verifies that the catalyst can be continuously operated in strong acid for more than 12 h.

[0084] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between each embodiment can be referred to each other.

[0085] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for the preparation of a layered cobalt tungsten oxide catalyst supported on nickel foam for efficient water splitting, characterized by, Comprising the following steps: S1, sequentially performing electrochemical deposition treatment on the foamed nickel with a cobalt source and an acid reagent as an electroplating solution, oxidation with a potassium hydroxide solution as an electroplating solution, and calcination to obtain ComCo3O4 / NF; S2, sequentially performing electrochemical deposition treatment on the ComCo3O4 / NF with a cobalt source and polyvinylpyrrolidone as an electroplating solution, and calcination to obtain AcCo3O4 / ComCo3O4 / NF; S3, sequentially performing electrochemical deposition treatment on the AcCo3O4 / ComCo3O4 / NF with a tungsten source as an electroplating solution, calcining, to obtain the foam nickel layered cobalt-tungsten oxide catalyst for efficient water splitting, denoted as W x O y / AcCo3O4 / ComCo3O4 / NF.

2. The production method according to claim 1, characterized by, In step S1: the cobalt source includes cobalt nitrate and / or cobalt sulfate; the electroplating solution is added in the form of an aqueous solution; in the electroplating solution, the concentration of the cobalt source is 0.1-0.2 mol / L, and the concentration of the acid reagent is 0.5-0.7 mol / L; the acid reagent includes boric acid and / or oxalic acid.

3. The preparation method according to claim 1, characterized in that, In step S1: the deposition current of the electrochemical deposition treatment is 15-20 mA, and the deposition time is 60-90 min; the concentration of the potassium hydroxide solution is 0.5-1 mol / L, and the current of the oxidation is 3-6 mA; the heating rate of the calcination is 5 ℃ / min, the temperature is 500 ℃, and the holding time is 3-5 h.

4. The method of claim 1, wherein, In step S2: the cobalt source includes cobalt nitrate and / or cobalt sulfate; the electroplating solution is added in the form of an aqueous solution; in the electroplating solution, the concentration of the cobalt source is 0.05-0.1 mol / L, and the concentration of polyvinylpyrrolidone is 1-2 g / L.

5. The preparation method according to claim 1, characterized in that, In step S2: the deposition current of the electrochemical deposition treatment is 3-6 mA, and the deposition time is 30-45 min; the heating rate of the calcination is 5 ℃ / min, the temperature is 350 ℃, and the holding time is 3-5 h.

6. The method of claim 1, wherein, In step S3: the tungsten source includes sodium tungstate and / or potassium tungstate; the electroplating solution is added in the form of an aqueous solution; in the electroplating solution, the concentration of sodium tungstate is 0.1-0.5 mol / L.

7. The preparation method according to claim 1, characterized in that, In step S3: the deposition current of the electrochemical deposition treatment is 10-15 mA, and the deposition time is 20-30 min; the heating rate of the calcination is 5 ℃ / min, the temperature is 350 ℃, and the holding time is 3-5 h.

8. The foamed nickel layered cobalt-tungsten oxide catalyst for efficient water decomposition prepared by the preparation method of any one of claims 1-7.

9. The use of the foamed nickel layered cobalt-tungsten oxide catalyst for efficient water decomposition of claim 8 in the electrolytic water hydrogen production.

10. A method for improving the hydrogen production effect and stability of electrolysis of water, characterized by, Comprising the following steps: Electrolytic water reaction is carried out in a three-electrode system with the foamed nickel layered cobalt-tungsten oxide catalyst for efficient water decomposition of claim 8 as a working electrode, a platinum sheet as a counter electrode, a saturated calomel electrode as a reference electrode, and 0.5 mol / L of H2SO4 solution as an electrolyte.

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