A method for preparing a nickel-molybdenum-based heterostructure photothermal catalyst supported on nickel foam and its application.

Abstract

This invention discloses a method for preparing a nickel-molybdenum-based heterostructure photothermal catalyst supported on nickel foam and its application. The preparation method includes the following steps: immersing nickel foam in a precursor solution containing nickel and molybdenum sources for a hydrothermal reaction to grow NiMo-based nanomaterials on the nickel foam; using the nickel foam with grown NiMo-based nanomaterials as the working electrode, electrodepositing is performed in an electrolyte containing nickel and copper sources to grow NiCu alloy nanomaterials on the NiMo-based nanomaterials; wherein a heterostructure interface structure is formed between the NiMo-based nanomaterials and the NiCu alloy nanomaterials, and the electronic structure of the catalyst is regulated by inducing electron transfer between the two phases of the heterostructure interface structure, resulting in a catalyst with extremely high electrocatalytic activity and stability for the hydrogen evolution reaction in water electrolysis. Furthermore, this catalyst can be used in electrolyzer-TE devices (photothermal-assisted water electrolysis devices) to effectively reduce the overall voltage of the water splitting cell.

Description

Technical Field

[0001] This invention relates to the field of non-precious metal electrolysis catalysts; more specifically, it relates to a method for preparing a nickel-molybdenum-based heterostructure photothermal catalyst supported on nickel foam and its application in photothermal-assisted water electrolysis for hydrogen production. Background Technology

[0002] Due to energy scarcity and the environmental crisis, the development of green, clean, and sustainable energy sources is urgently needed. Hydrogen, as a novel energy source, boasts high energy density and is clean and efficient. Hydrogen production through water electrolysis has recently become a hot topic and has been widely studied. Its high efficiency and the fact that the products are H2 and O2, which can be recycled and save resources, make it a viable option. Among currently known catalysts, Pt and Ru-based catalysts are considered to have the highest HER and OER catalytic activities, respectively; however, their high cost, low stability, and poor overall stability hinder large-scale commercialization. Therefore, there is a need to vigorously develop cost-effective non-precious metal catalysts.

[0003] Phosphates, sulfides, and nitrides of transition metals (such as Fe, Co, Cu, Mo, and Ni) have been widely reported as alternatives to noble metals in HER catalysts. Among these, transition metal oxides and sulfides have become promising electrocatalytic materials due to their eco-friendliness, abundant resources, and strong catalytic properties. Although transition metal oxides are very stable, they are generally catalytically inert for basic HER reactions due to their slow kinetics. By constructing heterostructures to maximize the exposure of active sites under harsh electrochemical conditions, improving conductivity, and optimizing electronic structure, the catalytic performance of transition metal oxide and sulfide catalysts can be optimized. Furthermore, research on hydrogen production through water electrolysis using renewable energy sources such as solar energy has attracted considerable attention. Integrating photothermal electrocatalytic materials with thermoelectric devices can significantly reduce the energy consumption in the water electrolysis hydrogen production process. Summary of the Invention

[0004] The present invention aims to further develop the existing technology to provide a method for preparing a nickel foam-supported nickel-molybdenum-based heterostructure photothermal catalyst and its application in photothermal-assisted water electrolysis for hydrogen production.

[0005] The first aspect of this invention provides a method for preparing a nickel-molybdenum-based heterostructure photothermal catalyst supported on nickel foam, comprising the following steps:

[0006] Nickel foam (NF) was immersed in a precursor solution containing nickel and molybdenum sources for hydrothermal reaction, and NiMo-based nanomaterials were grown on the nickel foam.

[0007] Using nickel foam after growing NiMo-based nanomaterials as the working electrode, electrodeposition was performed in an electrolyte containing nickel and copper sources to grow NiCu alloy nanomaterials on the NiMo-based nanomaterials.

[0008] The NiMo-based nanomaterials and the NiCu alloy nanomaterials form a heterogeneous interface structure.

[0009] Furthermore, the NiMo-based nanomaterial is a nickel-molybdenum-based oxide, specifically NiMoO4.

[0010] Furthermore, the hydrothermal reaction is carried out at a temperature of 120–200°C for a duration of 3–8 hours.

[0011] Furthermore, the electrodeposition is a constant current density deposition, with a deposition current density of -0.1 to -0.3 A / cm². -2 The deposition time is 500–800 s.

[0012] Furthermore, the molar concentration of the nickel source in the precursor solution is 0.01–0.1 M, and the molar concentration of the molar source is 0.005–0.05 M.

[0013] Furthermore, the nickel source in the precursor solution is nickel nitrate, and the molybdenum source is ammonium molybdate.

[0014] Furthermore, the NiMo-based nanomaterial is a nickel-molybdenum-based sulfide, and the precursor solution also contains thiourea at a molar concentration of 0.1–0.5 M.

[0015] Furthermore, the molar concentration of the nickel source in the electrolyte is 0.01–0.1 M, and the molar concentration of the copper source is 0.01–0.1 M.

[0016] Furthermore, the nickel source in the electrolyte is nickel sulfate, and the copper source is copper sulfate.

[0017] Furthermore, the electrolyte also contains ammonium sulfate with a molar concentration of 0.01 to 0.05 M.

[0018] The second aspect of the present invention discloses the application of the nickel foam-supported nickel-molybdenum-based heterostructure photothermal catalyst obtained by the aforementioned preparation method in photothermal-assisted water electrolysis for hydrogen production.

[0019] The technical solution of the present invention has the following beneficial effects:

[0020] This invention uses nickel foam as a substrate. First, NiMo-based oxide or sulfide nanomaterials are synthesized on the nickel foam substrate using a hydrothermal method. Then, NiCu alloy nanomaterials are grown on the NiMo-based oxide or sulfide nanomaterials by electrochemical deposition, constructing a heterogeneous interface between the two phases. This not only increases the active sites of the catalyst but also regulates the electronic structure of the catalyst and optimizes the adsorption energy of intermediates through charge transfer between the two phases, thereby promoting the electrocatalytic reaction.

[0021] Under alkaline conditions, both NiMo-based oxides and sulfides exhibit strong adsorption capabilities for oxygen-containing intermediates, demonstrating excellent OER catalytic activity; simultaneously, they can construct oxygen vacancies (O... v To improve its hydrogen evolution performance, during the HER process, water is preferentially adsorbed onto oxygen vacancies (O2). v The H* substance after hydrolysis is adsorbed onto O. v The nearby activated O sites promote subsequent H2 generation reactions.

[0022] Furthermore, the catalyst of the present invention has superhydrophilicity and excellent photothermal properties. When used in an electrolyzer-TE device (photothermal assisted water electrolysis hydrogen production device), it can effectively reduce the overall voltage of the water splitter.

[0023] To more clearly illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0024] Figure 1 This is the XRD pattern of NiCu / NiMoO4 in the catalyst of Example 1;

[0025] Figure 2 In the image: a is the Ni 2p XPS spectrum of the catalysts in Example 1 and Comparative Example 2NiCu / NF; b is the Cu 2p XPS spectrum of the catalysts in both examples; c is the Mo3d XPS spectrum of the catalysts in Example 1 and Comparative Example 1NiMoO4 / NF; d is the O1s XPS spectrum of the catalysts in both examples.

[0026] Figure 3 In the image: a) SEM image of the catalyst in Comparative Example 1, b) SEM image of the catalyst in Comparative Example 2, c) SEM image of the catalyst in Example 1.

[0027] Figure 4 In the image, 'ac' represents TEM images of the catalyst from Example 1.

[0028] Figure 5 In the diagram: a is a comparison of the HER linear sweep voltammetry (LSV) curves of Example 1, Comparative Examples 1 and 2, and the commercial Pt / C catalyst; b is a comparison of their Tafel slopes; c is a comparison of their bilayer capacitance used to evaluate the electrochemical surface area (ECSA); and d is a HER chronovoltage (CP) curve of the catalyst of Example 1.

[0029] Figure 6In the diagram: a is a comparison of the linear sweep voltammetry (LSV) curves of OER for Example 1, Comparative Examples 1 and 2 and the commercial RuO2 catalyst; b is a comparison of their Tafel slopes; c is a comparison of their bilayer capacitance used to evaluate electrochemical surface area (ECSA); d is a comparison of the chronovoltaic (CP) curves of OER for the catalyst of Example 1.

[0030] Figure 7a This is a comparison chart of the total water splitting LSV of Example 1 and the commercial catalyst. Figure 7b The Faraday efficiency (FE) diagram of the catalyst in Example 1 was obtained through testing and calculation using a hydrogen production efficiency testing system. Figure 7c This is the chronovoltage curve (CP) of the total water splitting of the catalyst in Example 1;

[0031] Figure 8a This is a comparison of the UV-Vis-NIR absorption spectra of the catalysts in Example 1, Comparative Examples 1 and 2. Figure 8b The surface temperatures of the catalysts and NF (nickel foam) in Examples 1, 1, and 2, as monitored in air, are shown. Figure 8c The temperature changes of the catalyst and NF in 1M KOH solution in Examples 1, 1, and 2 are shown.

[0032] Figure 9 In the table: a) is the total water splitting performance of the catalyst of Example 1 under both illuminated and unilluminated conditions tested in an electrolyzer without a thermoelectric device; b) is the total water splitting performance of the catalyst of Example 1 under both illuminated and unilluminated conditions tested in an electrolyzer using a thermoelectric device; c) is the total water splitting performance of the catalyst of Example 1 under a current density of 50 mA cm⁻¹. -2 The following stability test graph;

[0033] Figure 10 This is a comparison chart of the oxygen vacancy content of the catalysts in Example 1 and Comparative Example 1;

[0034] Figure 11 This is a comparison diagram of the hydrophilic contact angles of the catalyst and pure nickel foam in Example 1;

[0035] Figure 12 This is the XRD pattern of NiCu / NiMoS in the catalyst of Example 2;

[0036] Figure 13 In the image: a is the Ni2p XPS spectrum of the NiCu / NiMoS / NF catalyst of Example 2 and the NiCu / NF catalyst of Comparative Example 4; b is the Cu 2p XPS spectrum of the two catalysts; c is the Mo 3d XPS spectrum of the NiMoS / NF catalyst of Example 2 and Comparative Example 3; d is the S2p XPS spectrum of the two catalysts.

[0037] Figure 14This is a SEM image of the catalyst in Comparative Example 4;

[0038] Figure 15 This is an SEM image of the catalyst from Example 2;

[0039] Figure 16 In the diagram: a is a comparison of the HER linear sweep voltammetry (LSV) curves of the catalysts of Example 2, Comparative Example 3 and Comparative Example 4; b is a comparison of their impedance; c is a comparison of their double-layer capacitance; d is a comparison of the HER chronovoltaic (CP) curves of the catalyst of Example 2.

[0040] Figure 17 In the figures: a) is a comparison of the UV-Vis-NIR absorption spectra of the catalysts of Example 2, Comparative Example 3, and Comparative Example 4; b) is the surface temperature of the catalysts of Example 2, Comparative Example 3, and Comparative Example 4 monitored in air; c) is the total water splitting performance of the catalyst of Example 2 under conditions of light and no light, tested in an electrolyzer using a thermoelectric device; d) is the total water splitting performance of the catalyst of Example 2 under conditions of light and no light, tested in an electrolyzer without a thermoelectric device. Detailed Implementation

[0041] Numerous specific details are set forth in the following description to provide a thorough understanding of the invention; however, the invention may also be implemented using other variations or substitutions. Therefore, other possible implementations that can be discerned by those skilled in the art based on the embodiments described herein are all within the scope of protection of this invention.

[0042] Example 1: Preparation of NiCu / NiMoO4 / NF catalyst

[0043] (1) The nickel foam (1cm*2cm) was ultrasonically cleaned sequentially in acetone, 6.0M hydrochloric acid solution, and deionized water for 30 minutes each, and then dried to obtain a clean nickel foam substrate. The nickel foam had a thickness of 1.6mm and a pore size of 110ppi.

[0044] (2) First, disperse 300 mg of nickel nitrate hexahydrate and 200 mg of ammonium molybdate tetrahydrate in 25 mL of deionized water (the molar concentration of nickel nitrate is 0.04 M and the molar concentration of ammonium molybdate is 0.0065 M), and sonicate for 300 s at room temperature to disperse them evenly. Then, transfer the uniformly dissolved solution to a Teflon high-pressure reactor.

[0045] (3) Place the cleaned nickel foam horizontally at the bottom of the inner liner of the Teflon high-pressure reactor, and then place the reactor in a forced-air drying oven, set the temperature to 150℃, and keep it at that temperature for 5 hours.

[0046] (4) The product obtained after the reaction was completed was washed three times with deionized water and anhydrous ethanol, and then placed in a vacuum drying oven at 60°C for 6 hours to obtain the NiMoO4 / NF precursor.

[0047] (5) Using the NiMoO4 / NF precursor as the working electrode, and the carbon rod and Ag / AgCl as the counter and reference electrodes, respectively, a 100 mL electrolyte was prepared containing 1050 mg nickel sulfate hexahydrate, 600 mg copper sulfate pentahydrate, and 350 mg ammonium sulfate (molar concentration of nickel sulfate: 0.04 M, molar concentration of copper sulfate: 0.024 M, molar concentration of ammonium sulfate: 0.026 M). In the three-electrode system, -0.2 A cm⁻¹ -2 The NiCu / NiMoO4 / NF catalyst was finally obtained by deposition under constant current for 650 s.

[0048] Example 2: Preparation of NiCu / NiMoS / NF catalyst

[0049] (1) The nickel foam (1cm*2cm) was ultrasonically cleaned sequentially in acetone, 6.0M hydrochloric acid solution, and deionized water for 30 minutes each, and then dried to obtain a clean nickel foam substrate. The nickel foam had a thickness of 1.6mm and a pore size of 110ppi.

[0050] (2) First, disperse 260 mg of nickel nitrate hexahydrate, 640 mg of ammonium molybdate tetrahydrate and 400 mg of thiourea in 25 mL of deionized water (the molar concentration of nickel nitrate is 0.03 M, the molar concentration of ammonium molybdate is 0.019 M and the molar concentration of thiourea is 0.2 M), and sonicate for 300 s at room temperature to disperse them evenly. Then, transfer the uniformly dissolved solution to a Teflon high-pressure reactor.

[0051] (3) Place the cleaned nickel foam horizontally at the bottom of the inner liner of the Teflon high-pressure reactor, then place the reactor in a forced-air drying oven, set the temperature to 120℃, and keep it at that temperature for 8 hours.

[0052] (4) The product obtained after the reaction was completed was washed three times with deionized water and anhydrous ethanol, and then placed in a vacuum drying oven at 60°C for 6 hours to obtain the NiMoS / NF precursor.

[0053] (5) Using the NiMoS / NF precursor as the working electrode, and the carbon rod and Ag / AgCl as the counter and reference electrodes, respectively, a 100 mL electrolyte containing 1050 mg nickel sulfate hexahydrate, 600 mg copper sulfate pentahydrate, and 350 mg ammonium sulfate was prepared. In the three-electrode system, -0.2 A cm⁻¹ -2 The NiCu / NiMoS / NF catalyst was finally obtained by deposition at a constant current density for 600 s.

[0054] Comparative Example 1: Preparation of NiMoO4 / NF catalyst

[0055] The difference between Comparative Example 1 and Example 1 is that step (5) in the preparation steps of Example 1 is omitted, i.e., no NiCu alloy is deposited.

[0056] Comparative Example 2: Preparation of NiCu / NF-650s catalyst

[0057] The difference between Comparative Example 2 and Example 1 is that steps (2)-(4) in the preparation steps of Example 1 are omitted, i.e., NiCu alloy is directly deposited on clean nickel foam.

[0058] Comparative Example 3: Preparation of NiMoS / NF Catalyst

[0059] The difference between Comparative Example 3 and Example 2 is that step (5) in the preparation steps of Example 2 is omitted, i.e., no NiCu alloy is deposited.

[0060] Comparative Example 4: Preparation of NiCu / NF-600s catalyst

[0061] The difference between Comparative Example 4 and Example 2 is that steps (2)-(4) in the preparation steps of Example 2 are omitted, i.e., NiCu alloy is directly deposited on clean nickel foam.

[0062] Morphology, dimensions and phase analysis of the examples and comparative examples

[0063] Figure 1 The X-ray diffraction (XRD) pattern of the catalyst in Example 1 shows peaks corresponding to NiMoO4 (PDF#13-0128) and NiMoO4 (PDF#31-0902), indicating the formation of the NiMoO4 phase. Simultaneously, peaks corresponding to Ni (PDF#87-0712) and Cu (PDF#99-0034) show varying degrees of shift, indicating the formation of the NiCu alloy phase. This demonstrates the successful preparation of the NiCu / NiMoO4 / NF catalyst in Example 1.

[0064] Figure 2 These are the XPS spectra of the catalysts in Example 1, Comparative Examples 1 and 2. Figure 2 a shows the Ni 2p XPS spectrum, with peaks at 856.43 eV and 874.51 eV corresponding to 2p³ / 2 and 2p¹ / 2, respectively, corresponding to Ni 2+ Ni 0 Peaks appear at 852.74 eV and 869.78 eV. Figure 2 The XPS spectrum of Cu 2p in b shows two peaks at 933.02 eV and 953.9 eV, which belong to Cu. 0 The two peaks at 935.52 eV and 955.65 eV belong to Cu.2+ . Figure 2 c shows the Mo 3d XPS spectrum, where the two peaks correspond to Mo 3d and Mo 4d, respectively. 5+ (232.15eV) and Mo 6+ (233.55eV). Figure 2 d shows the O1s XPS spectrum, where three peaks are attributed to hydroxyl (OH), oxygen vacancies, and lattice oxygen (MO). Figure 2 The test results show that NiCu / NiMoO4 heterostructures were grown in situ on the surface of nickel foam by hydrothermal-electrochemical deposition.

[0065] Figure 3 Image a and c are field emission scanning electron microscope (FE-SEM) images of the catalysts in Comparative Examples 1 and 2, and Example 1, respectively. Figure 3 a shows the rod-shaped NiMoO4 nanomaterials grown on nickel foam in Comparative Example 1. Figure 3 b shows the needle-like NiCu alloy nanomaterials in Comparative Example 2. Figure 3 c shows the growth state of NiCu alloy nanomaterials on NiMoO4 nanorods in Example 1.

[0066] Figure 4 Image ac is a transmission electron microscope (TEM) image of the catalyst in Example 1. Figure 4 The high-resolution transmission electron microscope (HRTEM) image of b shows two different lattice stripes, with a spacing of 0.21 nm corresponding to the (111) crystal plane of NiCu and a spacing of 0.371 nm corresponding to the (021) crystal plane of NiMoO4. The image also shows that the two phases NiCu and NiMoO4 form a heterogeneous interface structure.

[0067] Figure 12 This is the X-ray diffraction (XRD) pattern of the catalyst in Example 2, including the pattern corresponding to Ni. 2.5 Mo6S 6.7 The spectral peak (PDF#39-0481) indicates the formation of the NiMoS phase. Simultaneously, the spectral peaks show shifts to Ni (PDF#87-0712) and Cu (PDF#99-0034), indicating the formation of the NiCu alloy phase. This demonstrates the successful preparation of the NiCu / NiMoS / NF catalyst in Example 2.

[0068] Figure 13 These are the XPS spectra of the catalysts in Example 2, Comparative Examples 3 and 4. Figure 13 a shows the Ni 2p XPS spectrum, with peaks at 856.10 eV and 873.71 eV corresponding to 2p. 3 / 2 and 2p 1 / 2, corresponding to Ni 2+ Ni 0 Peaks appear at 852.90 eV and 870.10 eV. Figure 13 The XPS spectrum of Cu 2p in b contains peaks at 933.11 eV and 953.21 eV, which belong to Cu. 0 The two peaks at 935.09 eV and 954.81 eV belong to Cu. 2+ . Figure 13 c shows the Mo 3d XPS spectrum, where the two peaks correspond to Mo 3d and Mo 4d, respectively. 5+ (231.85eV), Mo 6+ (232.76eV). Figure 13 d shows the S2p XPS spectrum, where three peaks are attributed to the 2p of SO and S. 3 / 2 and 2p 1 / 2 track. Figure 13 The test results show that NiCu / NiMoS heterostructures were grown in situ on the surface of nickel foam by hydrothermal-electrochemical deposition.

[0069] Figure 14 This is a field emission scanning electron microscope (FE-SEM) image of the catalyst in Comparative Example 3, showing the bulk NiMoS grown on nickel foam in Comparative Example 3. Figure 15 The image shows a field emission scanning electron microscope (FE-SEM) image of the catalyst in Example 2, which shows the heterostructure NiCu / NiMoS grown on nickel foam in Example 2.

[0070] Electrocatalytic performance tests of examples and comparative examples

[0071] The three-electrode system was tested in a 1 mol / L KOH solution saturated with N2; the reference electrode was an Ag / AgCl electrode, and the counter electrode was a carbon rod / Pt sheet electrode.

[0072] The water splitting test conditions were as follows: the test was conducted in a 1 mol / L KOH solution saturated with N2; the reference electrode and the counter electrode were both catalysts prepared in Example 1 or 2.

[0073] Figure 5 a is a comparison of the HER linear sweep voltammetry (LSV) curves for Example 1, Comparative Examples 1 and 2, and a commercial Pt / C catalyst, where NiCu / NiMoO4 / NF curves are at 10 mA cm⁻¹. -2 and 100mA cm -2 The HER overpotentials at current densities were 18 mV and 154 mV, respectively, and the catalytic activity was significantly better than that of NiMoO4 / NF, NiCu / NF and commercial Pt / C. Figure 5b is the Tafel comparison plot, where NiCu / NiMoO4 / NF has the lowest Tafel slope (34mV dec). -1 This indicates that NiCu / NiMoO4 / NF has faster reaction kinetics; Figure 5 c is the double-layer capacitor (C dl A comparison chart used to evaluate the electrochemical surface area (ECSA) of NiCu / NiMoO4 / NF. dl 37mF cm -2 This indicates that it can provide more active sites during the HER process. Figure 5 d is the chronovoltage curve (CP) of NiCu / NiMoO4 / NF at 50 mA cm⁻¹. -2 The catalytic activity of NiCu / NiMoO4 / NF showed almost no decline after operating continuously for over 100 hours at the specified current density. Figure 5 Overall, the test results show that NiCu / NiMoO4 / NF exhibits better HER catalytic performance compared to Comparative Examples 1 and 2 and the commercial Pt / C catalyst.

[0074] Figure 6 a is a comparison of the linear sweep voltammetry (LSV) curves of OER for Example 1, Comparative Examples 1 and 2, and the commercial RuO2 catalyst. It can be seen that NiCu / NiMoO4 / NF exhibits the lowest overpotential at 10 mA cm⁻¹. -2 The overpotential of OER is 248mV at 100mA cm⁻¹. -2 The OER overpotential is 330mV, and the OER performance is significantly better than NiMoO4 / NF and commercial RuO2 catalysts. Figure 6 b is a comparison of Tafel slopes; NiCu / NiMoO4 / NF exhibits the lowest Tafel slope (27mV dec). -1 This indicates that NiCu / NiMoO4 / NF has faster reaction kinetics; Figure 6 c is the double-layer capacitance used to evaluate the electrochemically active surface area (ECSA). dl (Comparison chart, where C of NiCu / NiMoO4 / NF) dl 40mF cm -2 This indicates that it can provide abundant active sites during the OER process. Figure 6 d is the chronovoltage curve (CP) of the NiCu / NiMoO4 / NF catalyst in Example 1, at 50 mA cm⁻¹. -2 The catalytic activity of NiCu / NiMoO4 / NF showed almost no decay after operating continuously for more than 100 hours at the specified current density.

[0075] Figure 7aThis is a comparison of the total water splitting LSV of NiCu / NiMoO4 / NF and a commercial catalyst from Example 1. NiCu / NiMoO4 / NF requires only 1.503V and 1.638V respectively to achieve 10mA cm⁻¹. -2 and 50mAcm -2 Its current density is far superior to that of commercial catalysts. Figure 7b The Faraday efficiency (FE) of NiCu / NiMoO4 / NF was calculated using a hydrogen production efficiency testing system. The calculated FE of the NiCu / NiMoO4 / NF catalyst is close to 100%, demonstrating its excellent catalytic activity. Figure 7c This is the chronovoltage curve (CP) of the NiCu / NiMoO4 / NF catalyst in Example 1, at 50 mA cm⁻¹. -2 The catalytic activity of NiCu / NiMoO4 / NF showed almost no decay after operating continuously for more than 100 hours at the specified current density.

[0076] Figure 16 a is a comparison of the linear sweep voltammetry (LSV) curves for the HER of catalysts in Example 2, Comparative Examples 3 and 4, where NiCu / NiMoS / NF exhibits significantly enhanced HER activity, showing the lowest overpotential; at 10 mA cm⁻¹ -2 The HER overpotential of NiCu / NiMoS / NF is 32mV, and its catalytic activity is significantly better than that of NiMoS / NF and NiCu / NF. Figure 16 b is the EIS comparison diagram, where NiCu / NiMoS / NF exhibits the lowest electrochemical impedance, indicating that NiCu / NiMoS / NF has a faster charge transfer rate; Figure 16 c is the double-layer capacitor (C dl A comparison chart used to evaluate the electrochemical surface area (ECSA) of NiCu / NiMoS / NF. dl 36mFcm -2 This indicates that it can provide more active sites in the HER process; Figure 16 d is the chronovoltage curve (CP) of the NiCu / NiMoS / NF catalyst in Example 2, at 50 mA / cm². -2 The catalytic activity of NiCu / NiMoS / NF showed almost no decay after operating continuously for more than 100 hours at the specified current density.

[0077] Photothermal performance tests of examples and comparative examples

[0078] The nickel foam-supported nickel-molybdenum-based heterostructure photothermal catalyst disclosed in this invention can be used as a hydrogen evolution electrode and / or an oxygen evolution electrode in, for example, the photothermal-assisted water electrolysis device disclosed in Chinese Invention Patent No. CN202210279172.1.

[0079] Figure 8a The images show the UV-Vis-NIR absorption spectra of catalysts from Examples 1, 1, and 2. Compared to Comparative Examples 1 and 2, the catalyst from Example 1 exhibits significantly enhanced absorption in the 200-2000 nm wavelength range, particularly effective absorption of near-infrared light. This enhanced absorption is attributed to both surface plasmon resonance (SPR) absorption of the NiCu alloy and the formation of the NiCu / NiMoO4 heterostructure, which promotes efficient separation of photogenerated electrons and holes at the heterostructure interface. In an air environment, such as... Figure 8b As shown, Example 1 reached a maximum temperature of 72.3℃ after 12 minutes, while Comparative Examples 1 and 2 and bare NF reached peak temperatures of 68.8℃, 60.6℃, and 49.9℃, respectively. Furthermore, under the same light intensity, the photothermal performance curves of Example 1 and Comparative Examples 1 and 2 in 1M KOH are shown below. Figure 8c As shown, the highest temperature of the electrolyte (53.5°C @ 90 min) when using Example 1 exceeded that of the comparative example, confirming the superior photothermal performance of Example 1.

[0080] The overall water splitting performance of the catalyst in Example 1 was tested in an electrolyzer-TE unit (photothermal assisted electrolysis of water to produce hydrogen). Figure 9 a represents the test results of Example 1 when the catalyst was used as both the hydrogen evolution electrode and the oxygen evolution electrode, without the use of a thermoelectric (TE) device, at a light intensity of 200 mW / cm². -2 The current density is 50 mA / cm². -2 At that time, the voltage of the fully electrolyzed water cell was measured to be 1.61V, which is lower than the voltage (1.65V) without light. Figure 9 b. The overall water splitting performance was studied when the catalyst of Example 1 was used as the hydrogen evolution electrode and oxygen evolution electrode in the thermoelectric device, with a temperature difference of 25°C between the electrolyzer and its bottom water-cooled plate and a current density of 50 mA / cm². -2 At that time, the voltage of the total water electrolysis cell in the electrolyzer was measured to be 0.96V; the electrolyzer-TE unit was operating under illumination with a current density of 50mA / cm². -2 The results of the 10-hour stability test are as follows: Figure 9 As shown in c, no significant attenuation was observed.

[0081] Figure 17a shows the UV-Vis-NIR absorption spectra of the catalysts in Example 2, Comparative Examples 3 and 4. It can be seen that Example 2 exhibits excellent absorption capacity in the 200-2000 nm wavelength range. In an air environment, such as... Figure 17 As shown in b, the highest temperature of Example 2 was 71.4°C at 12 min, while the peak temperatures of Comparative Examples 3 and 4 and bare NF were 68.8°C, 58.5°C and 48.6°C, respectively. Figure 17 c. The overall water decomposition performance was studied when the catalyst of Example 2 was used as the hydrogen evolution electrode in the thermoelectric device, with a temperature difference of 25°C between the electrolyzer and its bottom water-cooled plate and a current density of 50 mA / cm². -2 At that time, the voltage of the fully electrolyzed water cell in the electrolyzer was measured to be 0.84V. Figure 17 The photothermal effect of Example 2 catalyst as the hydrogen evolution electrode and without the use of a thermoelectric (TE) module was investigated to promote the entire water splitting reaction at a light intensity of 200 mW / cm². -2 The current density is 50 mA / cm². -2 At that time, the voltage of the fully electrolyzed water cell was measured to be 1.61V, which is lower than the voltage (1.83V) without light.

[0082] Oxygen vacancy content test in examples and comparative examples

[0083] like Figure 2 As shown in d, the three peaks in the O1s XPS spectrum of NiCu / NiMoO4 / NF are attributed to hydroxyl (OH), oxygen vacancy (O), and oxygen vacancy (O), respectively. v The catalysts NiCu / NiMoO4 / NF and NiMoO4 / NF exhibit both lattice oxygen (MO) and lattice oxygen (MO), with the oxygen vacancy intensity in NiCu / NiMoO4 / NF being higher than that in NiMoO4 / NF. To further confirm the presence of oxygen vacancies, electron paramagnetic resonance (EPR) technology was used to investigate the presence of oxygen vacancies in NiCu / NiMoO4 / NF and NiMoO4 / NF. 4 / NF was tested.

[0084] Figure 10 At g = 2.003, both the NiCu / NiMoO4 / NF and NiMoO4 / NF catalysts exhibit a strong signal corresponding to oxygen vacancies. Importantly, the EPR signal of NiCu / NiMoO4 / NF is stronger than that of NiMoO4 / NF, indicating a greater abundance of oxygen vacancies in NiCu / NiMoO4 / NF, consistent with XPS results. Abundant oxygen vacancies can enhance the conductivity of the electrocatalyst, facilitate the adsorption and dissociation of water and other reaction intermediates, optimize the binding strength of reaction intermediates, and improve the electrocatalytic performance of NiCu / NiMoO4 / NF.

[0085] Hydrophilicity tests of examples and comparative examples

[0086] Figure 11The surface properties of the electrocatalyst were revealed by measuring the contact angles between NiCu / NiMoO4 / NF and nickel foam (NF) substrates at solid-liquid and solid-gas interfaces. The contact angle of nickel foam (NF) was 115.63°, indicating that it is a hydrophobic material. In contrast, the contact angle of NiCu / NiMoO4 / NF was 0°, indicating that the NiCu / NiMoO4 / NF electrocatalyst exhibits superhydrophilicity. This superhydrophilicity facilitates contact between the solution and the material surface, thereby accelerating the reaction kinetics and further improving the electrocatalytic efficiency.

[0087] Although the present invention has been described above through specific embodiments, it should be understood that any equivalent improvements made by those skilled in the art in accordance with the present invention without departing from the scope of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a foam nickel supported nickel-molybdenum based heterostructure photo-thermal catalyst, comprising the following steps: The nickel foam is immersed into a precursor solution containing a nickel source and a molybdenum source to perform a hydrothermal reaction, so as to grow a NiMo-based nanomaterial on the nickel foam; wherein, The temperature of the hydrothermal reaction is 120-200℃, and the time is 3-8h, and the NiMo based nanomaterial is NiMoO4. The foam nickel after growing the NiMo based nanomaterial is used as a working electrode, and electrodeposition is performed in an electrolyte containing a nickel source and a copper source to grow a NiCu alloy nanomaterial on the NiMo based nanomaterial. The NiMo based nanomaterial and the NiCu alloy nanomaterial form a hetero-interface structure.

2. The method of claim 1; wherein, The electrodeposition is constant current density deposition, the deposition current density is -0.1 to -0.3 Acm -2 , and the deposition time is 500 to 800 s.

3. The method of claim 1; wherein, The molar concentration of the nickel source in the precursor solution is 0.01-0.1M, and the molar concentration of the molybdenum source is 0.005-0.05M. 4.The method of claim 3, wherein the nickel source is nickel nitrate, and the molybdenum source is ammonium molybdate.

5. The method of claim 3; wherein, The NiMo based nanomaterial is a nickel-molybdenum based sulfide, and the precursor solution further contains thiourea with a molar concentration of 0.1-0.5M.

6. The method of manufacturing according to claim 1; wherein, The molar concentration of the nickel source in the electrolyte is 0.01-0.1M, and the molar concentration of the copper source is 0.01-0.1M.

7. The method of claim 6; wherein, The nickel source is nickel sulfate, the copper source is copper sulfate, and the electrolyte further contains ammonium sulfate with a molar concentration of 0.01-0.05M. 8.Use of the foam nickel supported nickel-molybdenum based heterostructure photo-thermal catalyst prepared by the method of any one of claims 1-7 in photo-thermal assisted electrolysis of water to produce hydrogen.

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