W1O / NiS / CC catalyst and preparation method and application thereof

Abstract

The invention provides a W1O / NiS / CC catalyst and a preparation method and application thereof, and belongs to the technical field of electrocatalyst preparation. Ni (NO3) 2.6 H2O and (NH4) 6H2W12O40. XH2O are used as raw materials, pretreated carbon cloth is used as a substrate, a Ni-W composite oxide precursor is prepared, then WO3 / NiO composite oxide is formed through calcination treatment, low-temperature vulcanization, medium-temperature phase change and high-temperature stabilization treatment are conducted, and the W1O / NiS / CC catalyst is obtained. The W1O / NiS / CC catalyst is prepared; in the catalyst, an O atom is coordinated with a W single atom, NiS is modified, and NiS is of a hexagonal nano-scale lattice structure; when the catalyst is applied to alkaline water electrolysis hydrogen production, a local electric field generated by interaction of W-O bonds contained in the catalyst and NiS crystal lattices can induce interface water structure reconstruction of a hydrogen evolution reaction, so that the hydrogen evolution reaction rate is increased.

Description

Technical Field

[0001] This invention belongs to the field of electrocatalyst preparation technology, specifically relating to a W1O / NiS / CC catalyst, its preparation method, and its application. Background Technology

[0002] The efficiency of alkaline water electrolysis for hydrogen production mainly depends on the Volmer process in the hydrogen evolution reaction (HER). The Volmer process is an important step in the electrochemical reaction, which refers to the process in which hydrogen ions are adsorbed on the electrode surface and gain electrons to form adsorbed hydrogen atoms in the HER. In the alkaline electrolyte, water molecules need to overcome the binding of strong hydrogen bond networks and be decomposed into hydrogen ions and hydroxide ions. The energy barrier of this process is as high as 2.41 eV, which is 2-3 orders of magnitude slower than the rate in acidic environments.

[0003] To improve the efficiency of hydrogen production through alkaline water electrolysis, catalysts are usually added to the electrolyte. Nickel sulfide (NiS) catalysts are the preferred raw materials due to their low cost and high conductivity. However, when NiS catalysts prepared by existing technologies are used in alkaline water electrolysis for hydrogen production, problems such as difficulty in controlling the microenvironment of the reaction interface in the electrolyte and strong binding force of hydrogen bond networks occur, resulting in a low hydrogen evolution reaction rate that is difficult to meet the requirements. Summary of the Invention

[0004] The main objective of this invention is to provide a W1O / NiS / CC catalyst, its preparation method, and its application, aiming to solve the problem that the hydrogen evolution reaction rate of NiS catalysts prepared by existing technologies is low when used in alkaline water electrolysis for hydrogen production.

[0005] To address the above problems, this invention provides a method for preparing a W1O / NiS / CC catalyst, comprising: Ni(NO3)2·6H2O and (NH4)6H2W 12 O 40 • xH2O dissolves in deionized water to obtain a mixed solution; The pretreated carbon cloth was vertically immersed in the mixed solution, and after the treatment was completed, it was taken out and dried to obtain the Ni-W composite oxide precursor. The Ni-W composite oxide precursor was calcined to obtain WO3 / NiO composite oxide; The WO3 / NiO composite oxide was subjected to low-temperature sulfidation, medium-temperature phase transformation, and high-temperature stabilization treatment to obtain the W1O / NiS / CC catalyst.

[0006] Optionally, the Ni(NO3)2·6H2O and (NH4)6H2W 12 O 40The ratio of xH2O to deionized water is 1g~2g : 0.52g~1.5g : 50mL~100mL.

[0007] Optionally, the pretreated carbon cloth is obtained based on the following steps: The carbon cloth was ultrasonically cleaned sequentially with 0.1 mol / L to 2 mol / L hydrochloric acid solution, acetone, and ethanol for 10 min to 20 min to obtain pretreated carbon cloth. The specifications of the carbon cloth can be determined based on the Ni(NO3)2·6H2O and (NH4)6H2W content in the mixed solution. 12 O 40 The concentration of xH2O is selected. In the technical solution of this invention, carbon cloth with a specification of 1cm×3cm×0.5mm can be selected as the substrate for preparing the catalyst, that is, the length of the carbon cloth is 1cm, the width is 3cm and the thickness is 0.5mm. In practical applications, other specifications can be selected according to the actual situation, without limitation.

[0008] Optionally, the drying treatment is performed at a temperature of 120℃~140℃ for 12h~16h; the calcination treatment is performed at a temperature of 550℃~600℃ for 4h~6h.

[0009] Optionally, the low-temperature vulcanization treatment includes the following steps: The WO3 / NiO composite oxide was transferred to a tube furnace, and a mixed gas flow consisting of 10% H2 and 90% Ar was introduced. The flow rate of the mixed gas was controlled at 80 mL / min to 120 mL / min. Then, CS2 gas was introduced, and the flow rate of CS2 gas was controlled at 3 mL / h to 10 mL / h. The temperature of the tube furnace was increased to 150℃ to 200℃ to 170℃ at a rate of 10℃ / min and held for 2 hours to complete the low-temperature vulcanization.

[0010] Optionally, the intermediate-temperature phase change treatment includes the following steps: Maintain the temperature of the tube furnace at 150℃~200℃, increase the temperature to 250℃~300℃ at a rate of 5℃ / min, and hold for 2 hours to complete the mesotemperature phase change.

[0011] Optionally, the high-temperature stabilization treatment includes the following steps: The temperature of the tubular furnace was maintained at 250℃~300℃, and then increased to 330℃~380℃ at a rate of 5℃ / min. The temperature was maintained for 2 hours. The mixed gas flow was then switched to Ar gas flow, and the flow rate of the Ar gas flow was controlled at 30mL / min~50mL / min. After the temperature of the tubular furnace dropped to room temperature, the W1O / NiS / CC catalyst was obtained.

[0012] Optionally, the WO3 / NiO composite oxide has a nanoscale lattice structure, wherein the particle size of WO3 is 1nm~2nm and the particle size of NiO is 50nm~100nm.

[0013] The present invention also provides a W1O / NiS / CC catalyst, which is prepared according to the above method.

[0014] This invention also provides an application of the W1O / NiS / CC catalyst, which is used in alkaline water electrolysis for hydrogen production.

[0015] Compared with the prior art, the beneficial effects that the technical method of the present invention can achieve are as follows: 1. In the technical solution of the present invention, Ni(NO3)2·6H2O and (NH4)6H2W are used. 12 O 40 Using xH2O as raw material and pretreated carbon cloth (CC) as substrate, a Ni-W composite oxide precursor was prepared. Subsequently, calcination was performed to form a WO3 / NiO composite oxide with a nanoscale lattice structure. After low-temperature sulfidation, medium-temperature phase transformation, and high-temperature stabilization, a W1O / NiS / CC catalyst was prepared. In this catalyst, O atoms are coordinated with W single atoms and modify NiS, which has a hexagonal nanoscale lattice structure. W single atoms are uniformly dispersed in the hexagonal NiS nanoplate lattice at a loading of 1.25 wt.%, and interact with the NiS lattice through WO bonds, generating a local electric field of 0.8 V / nm. The WO bond length in the W1O / NiS / CC catalyst is 2.18 Å, and the coordination number is 2.3. 2. The W1O / NiS / CC catalyst prepared using the technical solution of this invention is applied to alkaline water electrolysis for hydrogen production. Under high-density current, the overpotential of the catalyst can remain at a low value. In the W1O / NiS / CC catalyst, the local electric field generated by the interaction between WO bonds and NiS lattice can induce the reconstruction of the interfacial water structure in the hydrogen evolution reaction, regulate the microenvironment of the solid-liquid interface of the electrolyte, orient the interfacial water molecules into an "H-down" configuration, weaken the binding force of the hydrogen bond network, increase the proportion of free water in the inner Helmholtz plane (IHP) from 21.6% to over 33.7%, and reduce the water dissociation energy barrier from 2.41 eV to 1.02 eV, thereby improving the hydrogen evolution reaction rate. Furthermore, during the electrolysis hydrogen production process, W1O and NiS in the W1O / NiS / CC catalyst are uniformly dispersed without agglomeration and maintain high electrocatalytic activity. Attached Figure Description

[0016] Figure 1 This is a flowchart of the preparation process of the W1O / NiS catalyst; Figure 2Sub-image A is a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image of the W1O / NiS catalyst; sub-image B is a high-magnification image of the rectangular region marked a in sub-image A; sub-image C is a high-magnification image of the square region marked b in sub-image B; sub-image D is a transmission electron microscope (TEM) image and energy-dispersive spectroscopy (EDS) elemental mapping map; sub-image E is a three-dimensional surface intensity distribution map of the W1O / NiS catalyst; sub-images F and G are both pixel intensity integral maps of the W1O / NiS catalyst; Figure 3 X-ray diffraction (XRD) patterns of different catalysts are shown. Figure 4 Sub-figure A shows the high-resolution X-ray photoelectron spectroscopy (XPS) spectra of W1O / NiS and NiS catalysts; sub-figure B shows the X-ray photoelectron spectroscopy (XPS) spectra of W1O / NiS and WO4 catalysts. x The high-resolution X-ray photoelectron spectroscopy (XPS) spectrum of Sᵧ; sub-figures C and D are X-ray absorption near-edge structure (XANES) spectra of W1O / NiS and NiS catalysts; sub-figures E and F are extended X-ray absorption fine structure (EXAFS) Fourier transform spectra of different catalysts. Figure 5 High-resolution X-ray photoelectron spectroscopy (XPS) spectra of different catalysts; Figure 6 This is a diagram illustrating the reaction mechanism of NiS with the W1O / NiS catalyst in the alkaline water electrolysis hydrogen production process. Figure 7 Subplot A shows the linear sweep voltammetry (LSV) polarization curves of different catalysts; subplot B shows the polarization curves of different catalysts at 10 mA / cm². 2 100mA / cm 2 Overpotential histogram at current density; Subplot C shows the Tafel slope of different catalysts; Subplot D shows the Δη / Δlog|j| ratio of different catalysts in different current density ranges; Subplot E shows the Nyquist plot of electrochemical impedance spectroscopy (EIS) of different catalysts at an overpotential of 100 mV; Subplot F shows the relationship between current density change (Δj) and scan rate; Subplot G shows the time-dependent current density curves of NiS and W1O / NiS catalysts; Subplot H shows the comparison of overpotentials of nickel-based base HER catalysts at different current densities. Figure 8 Sub-figures A and B are in-situ Raman spectra; sub-figure C is the interfacial water structure evolution diagram corresponding to sub-figures A and B; sub-figures D and E are... Figure 3 In-situ XPS quantitative analysis of subplots A and B shows the corresponding water dissociation efficiency; subplot F is a schematic diagram of the charge redistribution mechanism. Figure 9Subfigure A is a schematic diagram of the free water distribution at the interface simulated by AIMD; subfigure B is a snapshot of the number of hydrogen bonds (H-bonds) and representative structures of water molecules at the interface of NiS and W1O / NSi in KOH solution; subfigure C is a radial distribution function (RDF) analysis diagram of the interface water molecule configuration and bonding analysis simulated by AIMD; and subfigure D is a schematic diagram of the free energy barrier formed by water dissociation and H2. Detailed Implementation

[0017] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The technical solutions of the various embodiments can be combined with each other, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0019] NiS catalysts are widely used in alkaline water electrolysis for hydrogen production due to their low cost and high conductivity. However, the rigid interface of NiS hydrogen bond network structure, with tetrahedral coordination forming four-coordinate complexes (4-HB•H2O) and double hydrogen bonds (2-HB•H2O) accounting for more than 50%, limits the accessibility of water. Currently, in order to improve the performance of NiS catalysts, surface defect design, heteroatom doping, and focusing on the number of active sites are generally adopted. However, there are still problems such as the difficulty in controlling the microenvironment of the solid-liquid interface in the electrolyte, the large binding force of the hydrogen bond network, as well as the high overpotential of the catalyst, easy aggregation, lack of polar groups at WS sites, and inability to effectively polarize the OH bonds in water molecules.

[0020] To address the above shortcomings, this invention provides a method for preparing a W1O / NiS / CC catalyst, comprising: Ni(NO3)2·6H2O and (NH4)6H2W 12 O 40 • xH2O dissolves in deionized water to obtain a mixed solution; The pretreated carbon cloth was vertically immersed in the mixed solution, and after the treatment was completed, it was taken out and dried to obtain the Ni-W composite oxide precursor. The Ni-W composite oxide precursor was calcined to obtain WO3 / NiO composite oxide. The WO3 / NiO composite oxide was subjected to low-temperature sulfidation, medium-temperature phase transformation, and high-temperature stabilization treatments to obtain the W1O / NiS / CC catalyst.

[0021] Compared with the prior art, the present invention uses Ni(NO3)2·6H2O and (NH4)6H2W 12 O 40 Using xH2O as raw material and pretreated carbon cloth as substrate, WO3 / NiO composite oxide is obtained through drying and calcination. Then, through low-temperature sulfidation, medium-temperature phase transformation and high-temperature stabilization treatment, W1O / NiS / CC catalyst is obtained. In the W1O / NiS / CC catalyst, NiS has a nanoscale lattice structure, and the O atoms of W1O are coordinated with W single atoms. NiS is modified to form WS sites with polar groups. These sites can effectively polarize the OH bonds in water molecules, orienting the water molecules at the hydrogen evolution reaction interface to an "H-down" configuration, thereby weakening the hydrogen bond lattice binding force, reducing the hydrolysis energy and improving the efficiency of the hydrogen evolution reaction.

[0022] In practical applications, to ensure that the concentration of compounds in the above mixed solution is appropriate, Ni(NO3)2·6H2O and (NH4)6H2W 12 O 40 The ratio of xH2O to deionized water can be 1g~2g : 0.52g~1.5g : 50mL~100mL.

[0023] Optionally, in Ni(NO3)2·6H2O and (NH4)6H2W 12 O 40 The dissolution of ·xH2O in deionized water can be aided by ultrasonic dispersion. It should be understood that in Ni(NO3)2·6H2O and (NH4)6H2W... 12 O 40 When xH2O is completely dissolved, the resulting mixed solution is clear and transparent.

[0024] It should be understood that the above-described vertical immersion treatment of the pretreated carbon cloth using a mixed solution ensures that the metal ions in the mixed solution are uniformly distributed on the surface of the carbon cloth. Optionally, ultrasonic assistance can be used in this treatment process to ensure that the metal ions in the mixed solution are uniformly embedded in the carbon cloth, and then the mixture is left to stand for 24 hours to ensure that the metal ions are uniformly dispersed.

[0025] In one possible implementation, the pretreated carbon cloth described above can be prepared based on the following steps: The carbon cloth was ultrasonically cleaned sequentially with 0.1 mol / L to 2 mol / L hydrochloric acid aqueous solution, acetone, and ethanol for 10 to 20 minutes to obtain pretreated carbon cloth.

[0026] Among them, acetone and ethanol can be pure acetone solutions and pure ethanol solutions with a purity of 100%.

[0027] Optionally, the specific parameters for the drying treatment can be: temperature of 120℃~140℃ and time of 12h~16h; the specific parameters for the calcination treatment can be: temperature of 550℃~600℃ and time of 4h~6h.

[0028] Based on this processing operation, it can be ensured that the obtained WO3 / NiO composite oxide has a nanoscale lattice structure, and that the particle size of WO3 is 1~2 nm and the particle size of NiO is 50~100 nm. Alternatively, the above drying process can be performed using a vacuum drying oven.

[0029] It should be understood that after drying, the resulting Ni-W composite oxide precursor consists of Ni(NO3)2 and (NH4)6H2W. 12 O 40 composition.

[0030] Alternatively, the obtained Ni-W composite oxide precursor can be calcined using a muffle furnace.

[0031] It should be understood that the carbon cloth mentioned above is carbon fiber cloth, also known as carbon fiber cloth or carbon fiber fabric.

[0032] In one possible implementation, the low-temperature sulfidation treatment of the above-mentioned WO3 / NiO composite oxide can be performed as follows: The WO3 / NiO composite oxide was transferred to a tube furnace, and a mixed gas flow consisting of 10% H2 and 90% Ar was introduced, maintaining a flow rate of 80 mL / min to 120 mL / min. Then, CS2 gas was introduced as the sulfur source, and its flow rate was maintained at 3 mL / h to 10 mL / h. The temperature of the tube furnace was increased to 150℃ to 200℃ at a rate of 10℃ / min and held for 2 hours to complete the low-temperature sulfidation. Based on this method, the initial sulfidation of the NiO surface in the WO3 / NiO composite oxide can be ensured, leading to the formation of NiS crystals.

[0033] It should be understood that the above-mentioned mixed gas flow of 10% H2 and 90% Ar refers to the gas composition in the tubular furnace being composed of 10% H2 and 90% Ar.

[0034] Optionally, the flow rate of the CS2 gas can be controlled by a bubbling method. Specifically, the CS2 gas is inserted into an inert liquid (such as silicone oil, mineral oil, or water) through a conduit. Bubbles will be generated in the inert liquid. The faster the CS2 gas flow rate, the more bubbles are generated per unit time, and the larger their volume. By adjusting the valve opening size or pressure at the CS2 gas inlet, bubbles are generated at a stable frequency, such as 1 to 5 per second, thereby controlling the CS2 gas flow rate. Optionally, a mass flow meter can be used to control the flow rate of the above-mentioned mixed gas flow.

[0035] In one possible implementation, the above-mentioned intermediate-temperature phase transformation treatment steps are as follows: after the aforementioned low-temperature sulfidation, the temperature of the tube furnace is maintained at 150℃~200℃, and then increased to 250℃~300℃ at a rate of 5℃ / min, and held for 2 hours to complete the intermediate-temperature phase transformation. Based on this, it can be ensured that in the WO3 / NiO composite oxide, NiO is completely transformed into hexagonal NiS crystals, and WO3 is sulfided into a WO / S coordination structure.

[0036] It should be understood that in the hexagonal NiS crystal structure, nickel (Ni) atoms and sulfur (S) atoms are arranged in a specific spatial manner to form a hexagonal crystal lattice structure.

[0037] In one possible implementation, the high-temperature stabilization process described above involves the following steps: After the intermediate-temperature phase change treatment, the temperature of the tube furnace is maintained at 250°C to 300°C, and then increased to 330°C to 380°C at a rate of 5°C / min. This temperature is maintained for 2 hours. The mixed gas flow is then switched to an Ar gas flow, with the Ar flow rate controlled at 30 mL / min to 50 mL / min. Once the tube furnace temperature has cooled to room temperature, the W1O / NiS / CC catalyst is obtained. Based on this, the complete conversion of the WO3 / NiO composite oxide into the W1O / NiS / CC catalyst can be ensured. Furthermore, the resulting catalyst exhibits high electrocatalytic activity and is less prone to aggregation during catalysis. In the catalyst, W1O is coordinated with O atoms and W single atoms, and NiS has a nanocrystalline structure.

[0038] It should be noted that, when NiS catalysts prepared using existing technologies are applied to alkaline water electrolysis for hydrogen production, the proportion of free water in the inner Helmholtz plane (IHP) is <21.6%, and the proton migration barrier is >0.78 eV. This results in NiS exhibiting a high efficiency at 10 mA / cm². 2 The overpotential under certain conditions is as high as 196 mV; at >500 mA / cm 2 At high current densities, insufficient supply of IHP free water at the reaction interface leads to a sharp drop in the activity of the NiS catalyst; at 1000 mA / cm², 2 Under these conditions, the activity of NiS catalyst will fail due to the depletion of IHP free water, making it difficult to meet the requirements of high-efficiency hydrogen production reaction technology.

[0039] In the process of hydrogen production by alkaline water electrolysis, the free water content of IHP has a significant impact on the rate of hydrogen evolution reaction. Taking KOH alkaline solution as an example, KOH is a strong electrolyte and will ionize after dissolving in water, producing a large amount of K⁺ and OH⁻. 1 Under the influence of an electric field, K⁺ carries water molecules with polar orientation toward the cathode. Due to the adsorption of ions in the inner Helmholtz layer, some water molecules are repelled. These repelled water molecules, which still exist in the double layer region, form IHP free water. This free water has a relatively high degree of freedom and can move freely to a certain extent, participating in related physicochemical reaction processes, such as ion transport and charge transfer. Therefore, the content of free water affects the reaction rate and efficiency of alkaline water electrolysis to produce hydrogen.

[0040] When the W1O / NiS / CC catalyst prepared in this invention is applied to alkaline water electrolysis for hydrogen production, the local electric field generated by the interaction between the WO bonds and the NiS lattice in the catalyst can induce the reconstruction of the interfacial water structure in the hydrogen evolution reaction, regulate the microenvironment of the solid-liquid interface of the electrolyte, and orient the interfacial water molecules to an "H-down" configuration. This weakens the binding force of the hydrogen bond network, increases the proportion of IHP free water to ≥30%, and lowers the water molecule dissociation energy barrier to below 1.02 eV, within the range of 200~1000 mA / cm². 2 The current density can maintain a stable supply of IHP free water, thus preserving the high activity of the catalyst and improving the reaction rate of alkaline water electrolysis for hydrogen production.

[0041] Example 1 A method for preparing a W1O / NiS / CC catalyst, such as Figure 1 As shown, it includes: S1. Precursor preparation: 1.0 g of Ni(NO3)2·6H2O and 0.52 g of (NH4)6H2W 12 O 40 ·xH2O mixture, wherein Ni(NO3)2·6H2O contains Ni 2+ The concentration is 0.08 M, (NH4)6H2W 12 O 40 ·xH2O in W 6+ The concentration was 0.008 M, therefore, the ratio of Ni atoms to W atoms in the corresponding compound was 10:1; subsequently, the mixed Ni(NO3)2·6H2O and 0.52 g of (NH4)6H2W were added. 12 O 40xH2O was dissolved in 50mL of deionized water and ultrasonically dispersed for 1h until completely dissolved, resulting in a clear and transparent mixed solution. The pretreated carbon cloth was then vertically immersed in the solution with ultrasonic assistance and stirred at room temperature. After standing for 24h, the metal salt in the mixed solution was allowed to adsorb onto the carbon cloth uniformly by combining with the hydroxyl groups on the surface of the carbon cloth through physical adsorption. The pretreated carbon cloth was then removed and placed in a vacuum drying oven and dried at 120℃ for 12h to obtain the Ni-W composite oxide precursor. The pretreated carbon cloth described above can be obtained by the following steps: ultrasonically cleaning the carbon cloth sequentially with 0.1 mol / L hydrochloric acid solution, acetone and ethanol liquid for 15 min to obtain the pretreated carbon cloth; S2. Calcination Treatment: The above Ni-W composite oxide precursor was placed in a muffle furnace and calcined at 550℃ for 4 hours. During the calcination process, under high temperature, the Ni(NO3)2 contained in the Ni-W composite oxide precursor decomposed into NiO nanoparticles with a particle size of 50~100 nm, and the (NH4)6H2W contained in the precursor was also calcined. 12 O 40 The carbon cloth is decomposed into WO3 nanoparticles with a particle size of 1~2nm, and NiO nanoparticles and WO3 nanoparticles are uniformly distributed on the surface of the pretreated carbon cloth, forming a WO3 / NiO composite oxide with a nanolattice structure. S3. Low-temperature sulfidation: The above WO3 / NiO composite oxide is transferred to a tube furnace, and a mixed gas flow consisting of 10% H2 gas and 90% Ar gas is introduced. The flow rate of the mixed gas is controlled at 100 mL / min. CS2 gas is used as the sulfur source, and CS2 gas is introduced again. The flow rate of CS2 gas is controlled at 5 mL / h by bubbling method. The tube furnace is heated to 170℃ at a rate of 10℃ / min and held for 2 hours, so that CS2 initially sulfidates the NiO surface and forms NiS lattice. S4, Medium-temperature phase transformation: After low-temperature sulfidation in S3, the temperature of the tube furnace is kept at 170℃ and raised to 280℃ at a rate of 5℃ / min. After holding for 2 hours, NiO is completely transformed into hexagonal NiS crystals, and WO3 is sulfided into a WO / S coordination structure. S5. High-Temperature Stability: After the intermediate-temperature phase transition in S4, the temperature of the tube furnace is maintained at 170℃ and increased to 360℃ at a rate of 5℃ / min, and held for 2 hours to ensure that W atoms are fully coordinated with the NiS crystal lattice to form WO and WS bonds, wherein the bond length of the WO bond is 2.18 Å and the bond length of the WS bond is 1.83 Å. Then, the above mixed gas flow is switched to Ar gas flow, and the gas flow rate is controlled at 30 mL / min. After the temperature of the tube furnace drops to room temperature, the W1O / NiS / CC catalyst is prepared.

[0042] The W1O / NiS / CC catalyst prepared in Example 1 was applied to alkaline water electrolysis for hydrogen production.

[0043] Comparative Example 1 was set up under Example 1. The difference between Comparative Example 1 and Example 1 is that only Ni(NO3)2·6H2O was used in the preparation of the precursor; the remaining reaction steps and reaction conditions were the same as those in Example 1; NiO composite oxide was obtained after S2 calcination treatment, and then NiS / CC catalyst was prepared by low-temperature sulfidation, medium-temperature phase transformation and high-temperature stabilization.

[0044] The W1O / NiS / CC catalyst prepared in Example 1 was characterized and compared with the NiS / CC catalyst prepared in Comparative Example 1. The results are as follows: Figures 2-5 As shown.

[0045] It should be noted that in the W1O / NiS / CC catalyst and NiS / CC catalyst based on carbon cloth (CC), CC serves as the catalyst substrate and does not participate in the catalytic process. Therefore, in order to more accurately describe the various performance characteristics of the catalyst, in this invention, all characterization analyses related to the W1O / NiS / CC catalyst and NiS / CC catalyst, including the markings in the figures and the corresponding language descriptions, use the description of W1O / NiS catalyst instead of W1O / NiS / CC catalyst, and the description of NiS catalyst instead of NiS / CC catalyst.

[0046] (1) The atomic-level structure of the W1O / NiS catalyst was characterized, and the results are as follows: Figure 2 As shown.

[0047] In the figure, sub-figure A is a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image of the W1O / NiS catalyst. In the figure, the isolated bright spots are W single atoms, and the bright striped lattice crystals are NiS nanoplate lattice. It can be seen that in the W1O / NiS catalyst prepared by the technical solution of the present invention, W in W1O exists at the single-atom level, and NiS is in the form of nanoplate lattice. By displaying the rectangular region marked 'a' in sub-figure A at high magnification, we obtain sub-figure B. As shown in sub-figure B, W single atoms are uniformly dispersed and exist in isolation in the bright NiS nanoplate lattice. Comparing with the scale bar in the figure, we can see that the particle size of W single atoms is <0.5nm. Displaying the marked square region b in sub-figure B at high magnification yields sub-figure C. As shown in sub-figure C, W single atoms are uniformly dispersed without agglomeration, as indicated in the figure. The NiS nanoplate lattice spacing is 0.26 nm, or 2.6 Å, which corresponds to the 101 crystal plane of NiS crystal.

[0048] Sub-figure D shows the transmission electron microscope (TEM) image and energy dispersive spectroscopy (EDS) elemental mapping of the W1O / NiS catalyst. As can be seen from the figure, the W1O / NiS catalyst is dispersed without agglomeration and contains Ni, S, W and O elements, which are uniformly dispersed.

[0049] Sub-image E is a three-dimensional surface intensity distribution map of the W1O / NiS catalyst, while sub-images F and G are pixel intensity integral maps of the W1O / NiS catalyst. Sub-image E shows that the intensity of the three-dimensional surface of the W1O / NiS catalyst is prominent. As shown in sub-images F and G, no diffraction peaks of the W-W bond signal were observed in the figures, which further verifies that W atoms are uniformly dispersed in the W1O / NiS catalyst in the form of W single atoms.

[0050] (2) X-ray diffraction (XRD) pattern analysis.

[0051] XRD analysis was performed on W1O / NiS and NiS catalysts, and compared with WO4 catalysts. x S y The XRD diffraction peaks of the catalyst and CC were compared, wherein the WO x Sᵧ and CC are commercially available finished products, WO x S y This indicates that the W element in the compound was not completely oxidized and sulfided, and the oxidation state of the compound is uncertain.

[0052] The results are as follows Figure 3 As shown in the figure, the W1O / NiS catalyst has a mixed structure of amorphous and crystalline states. At position JCPDS No. 20-1280, only the characteristic peaks of hexagonal NiS crystals are displayed, and no W1O peaks are observed. x S y The crystal phase diffraction peaks indicate that in the W1O / NiS catalyst, W is embedded in the NiS nanolattice after being coordinated with O atoms at the W atom level, rather than existing in the form of metal particles.

[0053] (3) Analysis of the crystal structure and chemical state of the catalyst, the results are as follows: Figure 4 and Figure 5 As stated above.

[0054] in, Figure 4 In the figure, sub-figure A shows the high-resolution X-ray photoelectron spectroscopy (XPS) spectra of W1O / NiS and NiS catalysts. According to the high-resolution Ni 2p3 / 2 spectrum, the NiS peak shifted from 852.6 eV to 852.7 eV, falling within the W1O / NiS peak range, a shift of 0.1 eV. This demonstrates electron transfer from Ni to W, forming Ni2O / Ni2O / NiS. + / Ni 2+Mixed valence state.

[0055] in, Figure 4 In the middle, sub-figure B represents the W1O / NiS catalyst and WO. x S y The high-resolution X-ray photoelectron spectroscopy (XPS) spectrum shows that the WO and WS double peaks split at 35.2 eV and 32.5 eV, which proves that WO and WS bonds coexist in the W1O / NiS catalyst and that an oxygen coordination structure exists.

[0056] like Figure 5 As shown, the catalysts are W1O / NiS, NiS, and WO. x The high-resolution X-ray photoelectron spectroscopy (XPS) spectrum of S shows that the MS peak intensity increases at 161.7 eV, and the SO peak appears at 168.3 eV. This indicates that in the W1O / NiS catalyst, some S atoms are covalently bonded to WO groups.

[0057] in, Figure 4 In the figure, sub-figures C and D show the X-ray absorption near-edge structure (XANES) spectra of W1O / NiS and NiS catalysts, compared with those of Ni foil (nickel-platinum), Ni2O3, and NiO, where Ni foil, Ni2O3, and NiO are commercially available products. The figures show that the K-edge absorption threshold of Ni atoms shifts to a higher energy level by 0.3 eV, indicating that Ni… 2+ →Ni + The electron transfer pathway shows that the L-edge of the W atom shifts to a lower energy level by 0.5 eV, indicating that W is in a mixed state of +4 to +5 valences, which further confirms the Ni→W electron transfer pathway.

[0058] in, Figure 4 In the figure, sub-figures E and F show the extended X-ray absorption fine structure (EXAFS) Fourier transform spectra of the W1O / NiS catalyst, and are compared with W foil (tungsten platinum), WO3, WO2, and WS2, where W foil, WO3, WO2, and WS2 are commercially available products. As shown in the figure, W is bonded to about 2.3 oxygen atoms, i.e., the coordination number of WO bonds is ≈2.3, and W is bonded to about 3.5 sulfur atoms, i.e., the coordination number of WS bonds is ≈3.5, thus confirming the six-coordinate structure of W in the W1O / NiS catalyst. W1O / NiS has a W-S / O scattering peak at 1.76 Å, and no WW bond signal appears at >2.7 Å, thus confirming that W has a single-atom-level coordination structure in the W atom coordinated to O atom.

[0059] in, Figure 4In the figure, sub-figure G shows the Wavelet transform (WT)-EXAFS analysis of the W1O / NiS catalyst. As can be seen from the figure, the atomic signal is located at 6.6 Å. -1 Furthermore, the peaks were separated from the characteristic peaks of W metal particles, which further verifies that W single atoms are dispersed at the atomic level in the W1O / NiS catalyst.

[0060] The W1O / NiS / CC catalyst prepared in Example 1 and the NiS / CC catalyst prepared in Comparative Example 1 were applied to an alkaline water electrolysis hydrogen production reaction, and the various reaction performances of the catalysts were tested during the reaction. The results are as follows: Figures 6-9 As shown.

[0061] It should be noted that in the W1O / NiS / CC catalyst and the NiS / CC catalyst based on carbon cloth (CC), CC serves as the catalyst substrate and does not participate in the catalytic process. Therefore, in the alkaline water electrolysis hydrogen production process, in order to more accurately describe the various chemical reaction performance characteristics of the catalyst, in this invention, all analyses related to the W1O / NiS / CC catalyst and the NiS / CC catalyst, including the markings in the figures and the corresponding language descriptions, use the term W1O / NiS catalyst instead of W1O / NiS / CC catalyst, and the term NiS / catalyst instead of NiS / CC catalyst.

[0062] (4) The reaction mechanism between NiS catalyst and W1O / NiS catalyst in alkaline water electrolysis for hydrogen production, such as Figure 6 As shown.

[0063] As shown in the figure, in the alkaline water electrolysis hydrogen production process, NiS acts as a basic catalyst, catalyzing the hydrogen evolution reaction (HER) under alkaline conditions and accelerating the reaction rate.

[0064] In the W1O / NiS catalyst, W1O is embedded in the NiS matrix in a single-atom structure, giving the W1O / NiS catalyst excellent controllability. It can optimize the binding mode of reactants and optimize the water molecule structure to bind in a direction favorable to the hydrogen evolution reaction. It has the function of regulating the charge distribution of the reaction interface and reconstructing the water molecule structure of the reaction interface. This significantly increases the supply of free water in the IHP and induces the water molecules in the reaction interface to an 'H-down' adsorption configuration with hydrogen facing down. At the same time, the W1O / NiS catalyst strengthens the WH bond interaction in the IHP, promotes the adsorption of hydrogen intermediates, and accelerates the breaking of H-OH bonds, promoting water dissociation, thereby significantly improving the rate of alkaline HER in alkaline water electrolysis for hydrogen production.

[0065] (5) The HER of the three-electrode system in alkaline water electrolysis for hydrogen production was tested, and the results are as follows: Figure 7 As shown.

[0066] Test conditions: CHI760E workstation was used, with a standard three-electrode configuration; working electrode: W1O / NiS, effective area 0.5 cm². 2 Reference electrode: Hg / HgO, saturated KCl solution at 25℃; Counter electrode: graphite rod, 5 mm in diameter; Electrolyte: N2 saturated 1 M KOH, pH=14.

[0067] Sub-figure A shows the linear sweep voltammetry (LSV) polarization curves of different catalysts. In the figure, the Pt / C catalyst is a commercially available finished catalyst. According to the curves in the figure, as the current density increases, the overpotential of the catalyst gradually increases. Under the same current density, the W1O / NiS catalyst has the lowest overpotential. This indicates that, under the same conditions, the W1O / NiS catalyst has the best catalytic effect on the hydrogen evolution reaction in the alkaline water electrolysis hydrogen production process.

[0068] Sub-figure B shows different catalysts at 10 mA / cm². 2 100mA / cm 2 The overpotential histogram at current density, compared with subplot A at 10 mA / cm². 2 100 mA / cm 2 Correspondingly, the LSV curve, after iR correction, shows that at 10 mA / cm 2 100 mA / cm 2 Under the given conditions, the overpotentials of the W1O / NiS catalyst were 77 mV and 169 mV, respectively, while the overpotentials of the NiS catalyst were 198 mV and 310 mV, respectively. Sub-figure A shows that at 1000 mA / cm²... 2 Under the given conditions, the overpotential of the W1O / NiS catalyst was 236 mV. In alkaline water electrolysis for hydrogen production, a lower overpotential indicates better electrocatalytic performance. Therefore, under the same conditions, the W1O / NiS catalyst significantly optimizes the hydrogen evolution reaction process compared to the NiS catalyst. This is because the coordination sites of W1O in the W1O / NiS catalyst effectively improve the microchemical environment on the surface of the NiS catalyst, thereby accelerating the Volmer step in the hydrogen evolution reaction and increasing the rate of alkaline water electrolysis for hydrogen production.

[0069] Sub-figure C shows the Tafel slopes for different catalysts. As can be seen from the figure, WO xThe slope of the Sᵧ catalyst is 358 mV / dec, while that of the NiS catalyst is 120 mV / dec. In comparison, the slope of the W1O / NiS catalyst is 77 mV / dec. Therefore, electrochemical desorption (Heyrovsky) is the rate-determining step (RDS). The lower the Tafel slope, the better the hydrogen evolution performance of the catalyst in alkaline water electrolysis for hydrogen production. AIMD simulation calculations show that under the W1O / NiS catalyst conditions, the energy barrier for water molecule dissociation in alkaline water electrolysis for hydrogen production decreases from 2.41 eV to 1.02 eV, and the proton transfer efficiency increases by 3.2 times. Therefore, in the Volmer step of alkaline water electrolysis for hydrogen production, the optimization effect of the W single-atom sites in the W1O / NiS catalyst enhances the kinetics of the two-step process of water molecule decomposition and proton transfer.

[0070] Sub-figure D shows the Δη / Δlog|j| ratio for different catalysts within different current density ranges; sub-figure D indicates that W1O / NiS has a current density range of 10~500 mA / cm². 2 Within the range, the ratio of Δη / Δlog|j| remains constant; for NiS in the same range, as shown in Figure C, the Tafel slope increases dramatically by >150mV / dec; this indicates that the HER mechanism of W1O / NiS remains unchanged over a wide current range, and the Heyrovsky step is always the rate-determining step in the electrocatalytic process; while for NiS at high current, RDS transforms into the Volmer step, and water adsorption or dissociation is restricted.

[0071] Sub-figure E shows the Nyquist plots of electrochemical impedance spectroscopy (EIS) for different catalysts at an overpotential of 100 mV. Sub-figure E shows that, according to in-situ EIS, the charge transfer resistance (Rct) of W1O / NiS is stable at -1.5 Ω, and the charge transfer resistance of NiS / CC is 4.4 Ω, confirming the stability of the W1O / NiS interface structure.

[0072] After normalizing the electrochemical active area (ECSA) of W1O / NiS, its current density is still significantly higher than that of NiS catalyst. This confirms that the improved activity of W1O / NiS catalyst prepared by the technical solution of this invention is due to the enhancement of intrinsic activity at the atomic or electronic scale of the catalyst, rather than simply caused by surface area effect.

[0073] Subplot F shows the relationship between current density change (Δj) and scan rate. The graph indicates that within the range of 5–25 mV / s, W1O / NiS, NiS, and WO... x S y The double-layer capacitance (Cdl) is 6.63 mF / cm. 2 4.72mF / cm 2 and 4.08 mF / cm 2This indicates that, under the same electrochemical reaction conditions, the W1O / NiS catalyst exhibits superior electrochemical catalytic activity.

[0074] Sub-figure G shows the time-dependent current density curves for NiS and W1O / NiS catalysts. As can be seen from the figure, at 0.2 A / cm²... 2 Under these conditions, the activity rate of the NiS catalyst decreased by more than 20% after 100 hours, while the activity rate of the W1O / NiS catalyst remained above 98% even after continuous reaction for more than 300 hours. Furthermore, under these conditions, the current density decay rate of the NiS catalyst was >22.3%, while that of the W1O / NiS catalyst was <5%. This indicates that the W1O / NiS catalyst has a stable structure.

[0075] The structure of the W1O / NiS catalyst was further determined in 5 M KOH solution. After continuous reaction at 60 °C for 1000 h, the overpotential increased by only 15 mV, remaining within the range of 500-2000 mA / cm². 2 After 100,000 pulsed current cycles, the activity rate is still >95%, indicating that the W1O / NiS / CC catalyst prepared by the technical solution of this invention has excellent corrosion resistance, fatigue resistance and structural stability.

[0076] Sub-figure H is a comparison of the overpotentials of nickel-based base HER catalysts at different current densities. As can be seen from the figure, the overpotentials of the catalysts deviate from each other depending on the metal ion coordinated with the nickel group. When the catalyst contains coordinated oxygen atoms, the overpotential is smaller at the same current density. This indicates that the coordination structure of oxygen atoms has a significant impact on the electrocatalytic activity of nickel-based base HER catalysts.

[0077] (6) The interfacial water structure regulation mechanism of alkaline water electrolysis for hydrogen production was verified, and the results are as follows: Figure 8 As shown.

[0078] Sub-figures A and B show in-situ Raman spectra. As can be seen from the figures, W1O / NiS exhibits high spectral density in the range of 3000–3800 cm⁻¹. -1 High diffraction peaks are observed in the range, particularly at 3200 cm⁻¹. -1 The diffraction peak at this location represents 4-coordinated water molecules (4-HB·H₂O). Compared to the corresponding diffraction peak of NiS, the intensity decreased by 45%. This indicates that the single-atom dispersed W1O sites disrupt the tetrahedral hydrogen bond network of water molecules on the W1O / NiS surface. In alkaline water electrolysis for hydrogen production, this can increase the content of free water, thereby improving the hydrogen evolution performance of alkaline water electrolysis. Furthermore, the peak intensity of free water in IHP is attributed to 3600 cm⁻¹. -1As shown by the diffraction peaks in the figure, the proportion of free water in W1O / NiS increases to 33.7% compared to 21.6% in NiS, and exhibits a reversible response with changes in potential. This indicates that the use of W1O / NiS catalyst can enhance the dynamic migration ability of interfacial water in the alkaline water electrolysis hydrogen production process. Furthermore, the intensity decreases dynamically by 32% after applying a potential of -0.2V, indicating that free water has a rapid response capability to participate in the water electrolysis hydrogen production reaction process.

[0079] Sub-figure C is the evolution diagram of the interfacial water structure corresponding to sub-figures A and B. As shown in the figure, when W1O / NiS is cathodically polarized, the proportion of free water (free-H2O) is >33.7%, and 4-HB·H2O is significantly reduced; when NiS is used, the proportion of 2HB·H2O increases to 57%, and free water decreases to 21.6%. This indicates that the hydrogen bond network at the W1O / NiS interface is disrupted, which can promote the generation of highly active free water.

[0080] Among them, subgraphs D and E are related to... Figure 3 In-situ XPS quantitative analysis of subplots A and B in the figure shows the corresponding water dissociation efficiency diagrams. The diagrams show the ratio (ROH / H2O+OH*) in the W1O / NiS catalyst. dis The W1O / NiS ratio is 2.3 times that of NiS, indicating that W1O / NiS has excellent water dissociation ability.

[0081] Sub-figure F is a schematic diagram of the charge redistribution mechanism. As can be seen from the figure, it can be calculated using density difference theory that electrons in the NiS substrate are transferred to the WO group. This indicates that the positive charge of W attracts the oxygen end of water molecules, promoting the penetration of water molecules through the inner layer of IHP.

[0082] (7) Theoretical simulation and mechanism analysis of the alkaline water electrolysis hydrogen production process, the results are as follows: Figure 9 As shown.

[0083] Sub-figure A is an AIMD simulation of the interfacial free water distribution in the alkaline water electrolysis hydrogen production reaction. The figure shows that in the inner layer of the double layer of W1O / NiS, the IHP free water density is significantly higher than that in NiS. This indicates that the WO sites disrupt the hydrogen bond network, causing the interfacial water to transform from the ordered 4-HB·H2O structure of the ice phase to the disordered free phase. Figure 6 The conclusion that free water in subgraph C is >33.7% is consistent with the conclusion that free water accounts for more than 33.7%, which together verify the dynamic water enrichment mechanism.

[0084] Sub-figure B shows a snapshot of the number and representative structure of hydrogen bonds (H-bonds) between NiS and W1O / NiS at the KOH interface. Analysis shows that in the alkaline water electrolysis hydrogen production process, the W1O / NiS catalyst, through the O atom coordination with the W single-atom structure, can induce the local electric field at the water interface of the alkaline water hydrogen production reaction to a "H-down" structure, thereby weakening the hydrogen bonds and promoting the directional transfer of protons. This method can be applied to other electrocatalysis technologies. Other coordination structures similar to the O atom coordination with the W single-atom structure described in this invention also have the effect of optimizing the interfacial microenvironment of proton coupling reactions such as CO2 reduction and nitrogen fixation. The technical solution of this invention provides a general paradigm for designing highly efficient electrocatalysts.

[0085] Subfigure C shows the AIMD simulated radial distribution function (RDF) analysis plot of the interfacial water molecule configuration and bonding analysis. As can be seen from the figure, in W1O / NiS, the WO structure is located at Wδ... + =+1.91e - At the site, through electrostatic attraction, the interfacial water is forced to form an H-down configuration, transforming water dissociation from a high-energy-barrier process into a near-spontaneous process. This is how η is achieved. 10 The W1O / NiS interface exhibits a low overpotential of 67 mV. Under an electric field of 300 K and 0.8 V / nm, compared to NiS, the average number of hydrogen bonds in water molecules at the W1O / NiS interface decreases from 3.8 to 2.5, the hydrogen bond energy decreases from 21.3 kJ / mol to 15.7 kJ / mol, the "H-down" orientation ratio increases from 32% to 67%, and the HW bond distance shortens to 2.15 Å, forming a highly efficient proton transfer channel. The water molecule diffusion coefficient reaches 3.8 × 10⁻⁶ mV. -5 cm 2 / s, ensuring a continuous and stable supply of IHP free water.

[0086] Sub-figure D shows the free energy barrier diagram for water dissociation and H2 formation. As can be seen from the figure, in W1O / NiS, the WO structural sites, through the dual effects of H-down geometric configuration manipulation and pd hybridized electronic structure optimization, reduce the water dissociation energy barrier by 42% compared to using a NiS catalyst. Simultaneously, through the synergistic effect of W dissociation and +Ni recombination at the two sites, a near-zero energy barrier for hydrogen evolution reaction is achieved. This is achieved by W1O / NiS at 1000 mA cm⁻¹. -2The fundamental reason why the electrocatalytic performance of WO3 surpasses that of Pt / C catalysts at high current densities is that by constructing NiS(100)-W1O type, the water dissociation energy barrier of W1O / NiS is calculated to be 1.02 eV, while that of NiS is 2.41 eV. The H adsorption free energy (ΔG_H) is -0.08 eV, which is close to the ideal value of 0 eV. This confirms that WO3 sites can polarize OH bonds through local electric field, thereby weakening the binding force of hydrogen bond network and accelerating the Volmer step.

[0087] Example 2 A method for preparing a W1O / NiS / CC catalyst, comprising: S1. Precursor preparation: 2g of Ni(NO3)2·6H2O and 1.5g of (NH4)6H2W 12 O 40 Mix xH2O and dissolve in 100mL of deionized water. Sonicate for 1h until completely dissolved to obtain a clear and transparent mixed solution. Vertically immerse the pretreated carbon cloth in the solution. Stir at room temperature with ultrasonic assistance and let stand for 24h. This allows the metal salt in the mixed solution to combine with the hydroxyl groups on the surface of the carbon cloth through physical adsorption and be uniformly adsorbed on the pretreated carbon cloth. After standing, remove the pretreated carbon cloth and place it in a vacuum drying oven. Dry at 140℃ for 12h to obtain the Ni-W composite oxide precursor. Optionally, the pretreated carbon cloth described above can be obtained based on the following steps: the carbon cloth is ultrasonically cleaned for 10 min in sequence with 2 mol / L hydrochloric acid solution, pure acetone solution and pure ethanol solution to obtain the pretreated carbon cloth; S2. Calcination Treatment: The above Ni-W composite oxide precursor was placed in a muffle furnace and calcined at 600℃ for 4 hours. During the calcination process, under high temperature, the Ni(NO3)2 contained in the Ni-W composite oxide precursor decomposed into NiO nanoparticles with a particle size of 50~100nm, and the (NH4)6H2W contained in the precursor was also calcined. 12 O 40 It decomposes into WO3 nanoparticles with a particle size of 1~2nm, and NiO nanoparticles and WO3 nanoparticles are uniformly distributed on the surface of carbon cloth, thus forming a WO3 / NiO composite oxide, which has a nanocrystalline structure. S3. Low-temperature sulfidation: The above WO3 / NiO composite oxide is transferred to a tube furnace, and a mixed gas flow consisting of 10% H2 gas and 90% Ar gas is introduced. The flow rate of the mixed gas is controlled at 80 mL / min. CS2 gas is used as the sulfur source, and CS2 gas is introduced again. The flow rate of CS2 gas is controlled at 10 mL / h by bubbling method. The tube furnace is heated to 150℃ at a rate of 10℃ / min and held for 2h, so that CS2 initially sulfidates the NiO surface and forms NiS lattice. S4, Medium-temperature phase transformation: After the low-temperature sulfidation in S3, the temperature of the tube furnace is kept at 150℃ and raised to 250℃ at a rate of 5℃ / min, and held for 2h, so that NiO is completely transformed into hexagonal NiS (JCPDS No.20-1280) crystal, and WO3 is sulfided into WO / S coordination structure. S5. High-Temperature Stability: After the intermediate-temperature phase transition described in S4, the temperature of the tube furnace is maintained at 250℃ and increased to 330℃ at a rate of 5℃ / min, and held for 2 hours to ensure that W atoms are fully coordinated with the NiS crystal lattice to form WO and WS bonds, wherein the bond length of the WO bond is 2.18 Å and the bond length of the WS bond is 1.83 Å. Then, the above mixed gas flow is switched to Ar gas flow, and the gas flow rate is controlled at 40 mL / min. After the temperature of the tube furnace drops to room temperature, the W1O / NiS / CC catalyst is prepared.

[0088] The prepared W1O / NiS / CC catalyst was applied to alkaline water electrolysis for hydrogen production.

[0089] Example 3 A method for preparing a W1O / NiS / CC catalyst, comprising: S1. Precursor preparation: 1.5g of Ni(NO3)2·6H2O and 1g of (NH4)6H2W 12 O 40 xH2O was mixed and dissolved in 80mL of deionized water. The mixture was ultrasonically dispersed for 1h until completely dissolved, resulting in a clear and transparent mixed solution. The pretreated carbon cloth was vertically immersed in the solution and stirred at room temperature with ultrasonic assistance. The solution was then allowed to stand for 24h, allowing the metal salts in the mixed solution to bind to the hydroxyl groups on the surface of the carbon cloth through physical adsorption and be uniformly adsorbed onto the carbon cloth. After standing, the pretreated carbon cloth was removed and placed in a vacuum drying oven at 130℃ for 6h to obtain the Ni-W composite oxide precursor. Optionally, the pretreated carbon cloth described above can be obtained based on the following steps: the carbon cloth is ultrasonically cleaned sequentially with 1 mol / L hydrochloric acid solution, acetone pure solution and ethanol pure solution for 20 min to obtain the pretreated carbon cloth; S2. Calcination Treatment: The above-mentioned Ni-W composite oxide precursor was placed in a muffle furnace and calcined at 580℃ for 6 hours. During the calcination process, under high temperature, the Ni(NO3)2 contained in the Ni-W composite oxide precursor decomposed into NiO nanoparticles with a particle size of 50~100nm, and the (NH4)6H2W contained in the precursor was also calcined. 12 O 40 It decomposes into WO3 nanoparticles with a particle size of 1~2nm, and NiO nanoparticles and WO3 nanoparticles are uniformly distributed on the surface of carbon cloth, thus forming a WO3 / NiO composite oxide, which has a nanocrystalline structure. S3. Low-temperature sulfidation: The above WO3 / NiO composite oxide is transferred to a tube furnace, and a mixed gas flow consisting of 10% H2 gas and 90% Ar gas is introduced. The flow rate of the mixed gas is controlled at 120 mL / min. CS2 gas is used as the sulfur source, and CS2 gas is introduced again. The flow rate of CS2 gas is controlled at 3 mL / h by bubbling method. The tube furnace is heated to 200℃ at a rate of 10℃ / min and held for 2h, so that CS2 initially sulfidates the NiO surface and forms NiS lattice. S4, Medium-temperature phase transformation: After the low-temperature sulfidation in S3, the temperature of the tube furnace is kept at 200℃ and heated to 300℃ at a rate of 5℃ / min, and held for 2h, so that NiO is completely transformed into hexagonal NiS (JCPDS No.20-1280) crystals, and WO3 is sulfided into WO / S coordination structure. S5. High-Temperature Stability: After the intermediate-temperature phase transition described in S4, the temperature of the tube furnace is maintained at 300℃ and increased to 380℃ at a rate of 5℃ / min, and held for 2 hours to ensure that W atoms are fully coordinated with the NiS crystal lattice to form WO and WS bonds, wherein the bond length of the WO bond is 2.18 Å and the bond length of the WS bond is 1.83 Å; then the above mixed gas flow is switched to Ar gas flow, and the gas flow rate is controlled at 50 mL / min. After the temperature of the tube furnace drops to room temperature, the W1O / NiS / CC catalyst is prepared.

[0090] The prepared W1O / NiS / CC catalyst was applied to alkaline water electrolysis for hydrogen production.

[0091] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for preparing a W1O / NiS / CC catalyst, characterized in that, include: Ni(NO3)2·6H2O and (NH4)6H2W 12 O 40 • xH2O dissolves in deionized water to obtain a mixed solution; The pretreated carbon cloth was vertically immersed in the mixed solution, and after the treatment was completed, it was taken out and dried to obtain the Ni-W composite oxide precursor. The Ni-W composite oxide precursor was calcined to obtain WO3 / NiO composite oxide; The WO3 / NiO composite oxide was subjected to low-temperature sulfidation, medium-temperature phase transformation, and high-temperature stabilization treatment to obtain the W1O / NiS / CC catalyst.

2. The method for preparing the W1O / NiS / CC catalyst according to claim 1, characterized in that, The Ni(NO3)2·6H2O and (NH4)6H2W 12 O 40 The ratio of xH2O to deionized water is 1g~2g : 0.52g~1.5g : 50mL~100mL.

3. The method for preparing the W1O / NiS / CC catalyst according to claim 1, characterized in that, The pretreated carbon cloth is obtained based on the following steps: The carbon cloth was ultrasonically cleaned sequentially with 0.1 mol / L to 2 mol / L hydrochloric acid solution, acetone, and ethanol for 10 to 20 minutes to obtain pretreated carbon cloth.

4. The method for preparing the W1O / NiS / CC catalyst according to claim 1, characterized in that, The drying process is carried out at a temperature of 120℃~140℃ for 12h~16h; the calcination process is carried out at a temperature of 550℃~600℃ for 4h~6h.

5. The method for preparing the W1O / NiS / CC catalyst according to claim 1, characterized in that, The low-temperature vulcanization treatment includes the following steps: The WO3 / NiO composite oxide was transferred to a tube furnace, and a mixed gas flow consisting of 10% H2 and 90% Ar was introduced. The flow rate of the mixed gas was controlled at 80 mL / min to 120 mL / min. Then, CS2 gas was introduced, and the flow rate of CS2 gas was controlled at 3 mL / h to 10 mL / h. The temperature of the tube furnace was increased to 150°C to 200°C at a rate of 10°C / min and maintained for 2 hours to complete the low-temperature vulcanization.

6. The method for preparing the W1O / NiS / CC catalyst according to claim 5, characterized in that, The intermediate-temperature phase change treatment includes the following steps: Maintain the temperature of the tube furnace at 150℃~200℃, increase the temperature to 250℃~300℃ at a rate of 5℃ / min, and hold for 2 hours to complete the mesotemperature phase change.

7. The method for preparing the W1O / NiS / CC catalyst according to claim 6, characterized in that, The high-temperature stabilization treatment includes the following steps: The temperature of the tubular furnace was maintained at 250℃~300℃, and then increased to 330℃~380℃ at a rate of 5℃ / min. The temperature was maintained for 2 hours. The mixed gas flow was then switched to Ar gas flow, and the flow rate of the Ar gas flow was controlled at 30mL / min~50mL / min. After the temperature of the tubular furnace dropped to room temperature, the W1O / NiS / CC catalyst was obtained.

8. The method for preparing the W1O / NiS / CC catalyst according to claim 5, characterized in that, The WO3 / NiO composite oxide has a nanoscale lattice structure, wherein the particle size of WO3 is 1nm~2nm and the particle size of NiO is 50nm~100nm.

9. A W1O / NiS / CC catalyst, characterized in that, The W1O / NiS / CC catalyst is prepared by the method according to any one of claims 1 to 8.

10. An application of a W1O / NiS / CC catalyst, characterized in that, The W1O / NiS / CC catalyst described in claim 9 is applied to alkaline water electrolysis for hydrogen production.

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