A reconfigurable activated nickel-iron / sulfide composite photoanode triggered by sacrificial nickel, and a preparation method and application thereof

Abstract

This invention relates to the field of photoelectrochemical technology, and in particular to a nickel-iron / sulfide composite photoanode activated by sacrificial nickel-triggered reconstruction, its preparation method, and its applications. This invention introduces a nickel-iron hydroxyl oxide layer onto the surface of an indium sulfide photoanode, utilizing the PEC activation process to trigger the selective leaching of sacrificial Ni components and surface porosification reconstruction. This drives deep chemical integration of Fe species with the sulfide substrate at the interface, forming stable Fe-S anchoring bonds. Under the synergistic effect of photoelectric bias and illumination, this structure can transform the originally weakly coupled static contact into an adaptive, strongly coupled catalytic interface in situ. While eliminating deep-level traps at the interface, it significantly increases the density of active sites and the interfacial hole transport dynamics, thereby significantly enhancing the current response and energy conversion efficiency of the photoanode in the photoelectrochemical water oxidation process.

Description

Technical Field

[0001] This invention relates to the field of photoelectrochemical technology, and in particular to a nickel-iron / sulfide composite photoanode that utilizes sacrificial nickel to trigger reconstruction activation, its preparation method, and its application. Background Technology

[0002] Photoelectrochemical (PEC) water splitting technology is a key pathway to convert fluctuating solar energy into high-energy-density hydrogen energy. The core challenges to its large-scale application lie in the extremely slow oxygen evolution reaction (OER) kinetics at the photoanode side and the intense interfacial charge recombination. Among numerous semiconductor materials, metal sulfides (such as In₂S₃) have attracted considerable attention due to their excellent visible light response range and charge transport capabilities. However, sulfide semiconductors are highly susceptible to surface photocorrosion at oxidation potentials, and severe carrier loss exists at the interface between their surface and the electrolyte, making it difficult to effectively utilize photogenerated holes and severely limiting the conversion efficiency of solar energy to hydrogen energy.

[0003] To improve interfacial kinetics, introducing nickel-iron (NiFe)-based oxygen evolution cocatalysts is a common strategy. However, existing research largely focuses on oxide semiconductor systems, with limited understanding of the interfacial chemical mechanisms between sulfide substrates and cocatalysts. Traditional deposition techniques typically form static contacts on sulfide surfaces through physical adsorption or weak chemical coupling. These "weakly coupled" interfaces often exhibit insufficient interfacial bonding and high contact resistance during actual PEC operation, and may even transform into new recombination centers, thus negating the catalytic advantages of the cocatalyst itself. Therefore, developing an in-situ control method that enables spontaneous reconstruction, strong chemical bonding, and efficient catalytic interfaces between the cocatalyst and sulfide substrate under operating conditions is of significant research value and practical importance for the fabrication of high-performance photoelectrochemical water splitting devices.

[0004] To address the severe interfacial charge recombination and sluggish oxygen evolution kinetics of metal sulfide photoanodes (such as In2S3), existing technologies mainly employ heteroelement doping, surface passivation layer coating, and the addition of external oxygen evolution co-catalysts. However, using heteroelement doping to control the band structure often involves stringent high-temperature processes and struggles to effectively suppress the regeneration of deep-level defects in complex oxidizing environments. While dense oxide passivation layers constructed using atomic layer deposition or spin coating can temporarily alleviate photocorrosion, they often significantly increase interfacial charge transfer resistance due to physical barriers, leading to the deactivation of active sites due to excessive blockage. Furthermore, conventionally supported nickel-iron (NiFe)-based co-catalysts exhibit significant chemical incompatibility with the sulfide substrate, resulting in a weakly coupled static contact at the interface. Under long-term bias and illumination, this unstable interface is highly susceptible to inducing new trapping centers due to chemical mismatch, thereby accelerating device performance degradation.

[0005] In traditional preparation methods, the cocatalyst layer supported on the sulfide substrate is often in a "static contact" with physical adsorption or weak chemical coupling. This weak coupling interface suffers from severe lattice mismatch and interfacial barriers, which cause photogenerated holes to easily undergo nonradiative recombination at the interfacial trapping centers before migrating to the surface to participate in the oxidation reaction, severely limiting the charge transfer efficiency.

[0006] Existing catalyst loading processes (such as conventional electrodeposition or spin coating) often form relatively dense, non-porous capping layers. Due to the lack of effective morphology control methods, the specific surface area of ​​the catalyst is limited, resulting in a low density of accessible active sites. This fails to provide sufficient catalytic centers for the oxygen evolution reaction (OER), thus exhibiting a high reaction overpotential.

[0007] Current mainstream modification strategies are mostly performed in the non-working state, which is a pre-defined static modification. This approach ignores the dynamic evolution of the material surface during the photoelectrochemical reaction, resulting in the co-catalyst being unable to spontaneously adjust to the optimal chemical coordination environment and oxidation state under actual bias voltage and illumination conditions. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is to overcome the problems of low charge transfer efficiency and high reaction overpotential in the prior art, thereby providing a method for constructing a strongly coupled catalytic interface based on sacrificial element-triggered reconstruction and photoelectrochemical (PEC) synergistic activation.

[0009] To address the aforementioned technical problems, this invention provides a method for preparing a nickel-iron / sulfide composite photoanode activated by sacrificial nickel-triggered reconstruction, comprising the following steps:

[0010] S11: Under illumination, an indium sulfide photoanode is used as the working electrode for photoelectrochemical deposition to obtain an IS photoanode (IS-NF) with NiFeOOH loaded on its surface; the electrolyte for the photoelectrochemical deposition includes water, potassium salt, iron salt and nickel salt;

[0011] S12: Under illumination, the IS photoanode with NiFeOOH loaded on its surface is used as the working electrode for photoelectrochemical activation to obtain the nickel-iron / sulfide composite photoanode activated by sacrificial nickel triggering reconstruction; the electrolyte during photoelectrochemical activation includes water and sodium salt.

[0012] Preferably, the method for preparing the indium sulfide photoanode includes the following steps:

[0013] S21: Mix indium salt and thiourea in water to obtain a precursor solution;

[0014] S22: The precursor solution is hydrothermally reacted on the surface of fluorine-doped tin oxide (FTO) conductive glass at 170-190°C for 5-7 h and then cooled to room temperature (25±5°C) to obtain the indium sulfide photoanode.

[0015] Furthermore, in step S22, after cooling, the product is washed with water and then vacuum dried at 45-55°C for 20-28 hours.

[0016] Furthermore, the indium salt is indium trichloride.

[0017] Furthermore, the mass ratio of the indium salt, thiourea, and water is 1-3:1-2:180-220.

[0018] Preferably, the potassium salt is potassium sulfate, the iron salt is ferrous sulfate, the nickel salt is nickel nitrate, and the sodium salt is sodium sulfate.

[0019] This invention introduces a nickel-iron hydroxyl oxide layer onto the surface of an indium sulfide (In2S3) photoanode. The PEC activation process triggers the selective leaching of sacrificial Ni components and surface porosification reconstruction, driving deep chemical integration of Fe species with the sulfide substrate at the interface, forming stable Fe-S anchoring bonds. Under the synergistic effect of photoelectric bias and illumination, this structure can transform the originally weakly coupled static contact into an adaptive, strongly coupled catalytic interface in situ. This eliminates deep-level traps at the interface while significantly increasing the density of active sites and the interfacial hole transport dynamics, thereby significantly enhancing the current response and energy conversion efficiency of the photoanode in the photoelectrochemical water oxidation process.

[0020] Preferably, in the electrolyte used for photoelectrochemical deposition, the mass ratio of potassium salt, iron salt, nickel salt, and water is 2-3:2-4:2-4:140-160. The proportion of potassium salt primarily regulates charge transport and the interfacial electric field within the electrolyte. The ratio of iron salt to nickel salt directly controls the chemical composition, crystal structure, and functional properties of the product. The proportion of water, however, affects the mass transfer process and reaction equilibrium during the photoelectrochemical deposition.

[0021] Preferably, the concentration of sodium sulfate in water is 0.4-0.6 M.

[0022] Preferably, in steps S11 and S12, a three-electrode system is used for photoelectrochemical activation, with Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode. The three-electrode system using an Ag / AgCl electrode as the reference electrode and a platinum mesh as the counter electrode is a widely used configuration. The potential of the Ag / AgCl electrode is determined by the balance between Ag / AgCl and Cl ions within the electrode. As long as the Cl ion activity is constant and the temperature is constant, its potential is very stable. Platinum is an inert metal and is not easily oxidized, corroded, or involved in reactions in a wide potential window and various electrolytes. This ensures that the reaction occurring on the counter electrode will not introduce contaminating impurities dissolved from the counter electrode, which, if they migrate to the surface of the working electrode, would severely interfere with the deposition process.

[0023] Preferably, the photoelectrochemical deposition uses a constant voltage of -0.1 to 0.2 V (relative to Ag / AgCl) for 5-15 min. Photoelectrochemical deposition is a process in which, under illumination, photogenerated electrons from a semiconductor electrode reduce and oxidize metal ions in an electrolyte, fixing them onto the electrode surface, thereby growing a material. The applied voltage directly determines the Fermi level position of the semiconductor electrode, thus controlling the energy transferred from photogenerated electrons to metal ions at the interface. The more negative the voltage, the stronger the driving force, the larger the current of the deposition reaction, the faster the nucleation rate, and the more rapidly the deposited layer tends to form. Conversely, a more positive voltage results in slower deposition, which may be more conducive to the formation of a dense, smooth film.

[0024] Preferably, the constant voltage for photoelectrochemical activation is 0.4 V to 0.8 V (relative to Ag / AgCl), and the time is 20-60 s. Photoelectrochemical activation typically involves electrochemically treating existing materials under light irradiation to alter their surface state, electronic structure, chemical composition, or introduce defects / dops, thereby improving their performance. The truly highly active phase of many catalytic materials is derived from the electrochemical oxidation / reduction transformation of precursors at a specific potential.

[0025] Specifically, the method for preparing the nickel-iron / sulfide composite photoanode activated by sacrificial nickel-triggered reconstruction includes the following steps:

[0026] (1) Cleaning the conductive substrate fluorine-doped tin oxide conductive glass (FTO): The FTO glass substrate is first ultrasonically cleaned in acetone, ethanol and deionized water for 30 minutes each, and repeated three times. Then it is placed in an oven at 60°C to dry for later use.

[0027] (2) Preparation of In2S3 photoelectrode: 2.61 g of indium trichloride tetrahydrate and 1.46 g of thiourea were placed in 200 mL of ultrapure water and dissolved sequentially for 20 minutes under magnetic stirring to form a uniform and transparent precursor solution. Two cleaned FTO glass plates were symmetrically placed in a 25 mL polytetrafluoroethylene-lined autoclave with the conductive side facing down. 10 mL of the above solution was slowly added dropwise to the liner. After sealing the autoclave, it was placed in a hydrothermal synthesis reactor and treated at 180 °C for 6 hours. After the reaction was completed, the system was allowed to cool naturally to room temperature. The sample was carefully removed and rinsed with deionized water. The final sample was dried in a vacuum oven at 50 °C for 24 hours to obtain the In2S3 photoanode (denoted as IS).

[0028] (3) Preparation of the photoelectrochemical deposition electrolyte: First, 150 mL of ultrapure water was placed in a reaction vessel. Then, 2.61 g of potassium sulfate was added under continuous stirring until it was completely dissolved. Next, 3.75 g of ferrous sulfate heptahydrate was added to the solution, and nitrogen gas was purged for 20 minutes under stirring to ensure an anaerobic environment. Finally, 3.92 g of nickel nitrate hexahydrate was added, and stirring was continued for 20 minutes under a nitrogen atmosphere to form a uniform light green solution. This solution was used as the electrolyte for photoelectrochemical deposition.

[0029] (4) Photoelectrodeposition of NiFeOOH: The obtained IS photoanode was placed in a three-electrode system, with Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode. The deposition process was carried out in the electrolyte prepared above. By applying a constant potential (relative to the Ag / AgCl electrode, the potential range was -0.1 to 0.2 V) and providing standard sunlight irradiation for 10 minutes, an IS photoanode with NiFeOOH loaded on the surface was obtained (denoted as IS-NF).

[0030] (5) IS-NF photoelectrochemical activation treatment: The obtained IS-NF photoanode was placed in a three-electrode system, with Ag / AgCl as the reference electrode, a platinum mesh as the counter electrode, and 0.5 M Na2SO4 solution as the electrolyte. An applied potential of 0.4 V to 0.8 V (relative to Ag / AgCl) was applied under illumination, and the activation time was controlled to be 20-60 s. The final sample was obtained (denoted as IS-NFA). Finally, the sample was washed with deionized water and stored in a vacuum drying oven.

[0031] The present invention also provides a nickel-iron / sulfide composite photoanode prepared by the above preparation method and activated by sacrificial nickel-triggered reconstruction.

[0032] The present invention also provides the application of the above-mentioned nickel-iron / sulfide composite photoanode activated by sacrificial nickel triggering in photoelectrochemical water splitting for hydrogen production.

[0033] Furthermore, the method of application is as follows: the nickel-iron / sulfide composite photoanode activated by sacrificial nickel triggering reconstruction is assembled into a photoelectrochemical cell, and water is decomposed photoelectrochemically in Na2SO4 aqueous solution.

[0034] Compared with the prior art, the above-described technical solution of the present invention has the following advantages:

[0035] 1) This invention achieves in-situ reconstruction of the interface from weak coupling to strong chemical anchoring, significantly suppressing carrier recombination: This invention drives interface reconstruction of the co-catalyst layer through a photoelectrochemical activation process, utilizing the selective leaching of sacrificial components as a triggering mechanism to drive deep chemical integration between the catalytic components and the sulfide substrate at the interface, forming stable anchoring bonds. Compared with traditional static deposition methods, this in-situ generated strong coupling interface can effectively reduce the trapping centers at the interface, fundamentally improving the separation efficiency of photogenerated carriers and significantly extending carrier lifetime.

[0036] 2) This invention constructs a high-density, nanoporous catalytically active microenvironment, significantly accelerating the oxygen evolution reaction kinetics: Through photoelectrochemical reconstruction, the morphology of the sulfide surface and catalyst layer undergoes morphological evolution, forming a highly open nanoporous architecture, which significantly increases the electrochemical active area and the density of effective active sites. Simultaneously, the amorphous active layer generated by the component evolution exhibits excellent intrinsic catalytic activity, significantly reducing interfacial hole transfer resistance and surface reaction overpotential, thus achieving ideal photoelectric conversion efficiency at a lower bias voltage, demonstrating superior charge injection capability and catalytic conversion rate.

[0037] 3) This invention possesses the unique process advantage of sacrificial component triggering, combining high stability and easy scalability: This invention utilizes the "sacrificial" leaching of specific elements to drive the redistribution of active species and interfacial bonding. This unique self-optimizing mechanism can be completed with only a short-term photoelectrochemical activation in a mild electrolyte environment. This process eliminates the need for high-temperature treatment or complex vacuum equipment, significantly reducing preparation difficulty and energy consumption. The activated interface exhibits excellent chemical stability under operating conditions, and its adaptive interface design provides a highly universal solution for developing high-performance, low-cost large-area photoelectrochemical systems. Attached Figure Description

[0038] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0039] Figure 1 In the figures, a to c are front views of the scanning electron microscope (SEM) of IS, IS-NF and IS-NFA in Embodiment 1 of the present invention, and d to f are transmission electron microscope (TEM) images of IS, IS-NF and IS-NFA in Embodiment 1 of the present invention.

[0040] Figure 2 These are the current density-voltage (JV) curves of IS, IS-NF, and IS-NFA in Embodiment 1 of the present invention; where the solid line represents the actual working state and the dashed line represents the dark current characteristic state.

[0041] Figure 3 These are the JV curves for different photoelectric activation voltages in Embodiment 2 of the present invention; where the solid line represents the actual working state and the dashed line represents the dark current characteristic state.

[0042] Figure 4 These are the JV curves for different photoelectric activation times in Embodiment 3 of the present invention; where the solid line represents the actual working state and the dashed line represents the dark current characteristic state. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0044] Example 1:

[0045] (1) The FTO glass substrate was ultrasonically cleaned in acetone, ethanol and deionized water for 30 minutes each, and repeated three times. Then it was placed in an oven at 60°C to dry for later use.

[0046] (2) Weigh 2.61 g of indium trichloride tetrahydrate and 1.46 g of thiourea, dissolve them in 200 mL of deionized water, and stir for 20 minutes to form a transparent precursor solution. Place two cleaned and dried FTO sheets, conductive side down, symmetrically into a 25 mL stainless steel reactor lined with polytetrafluoroethylene. Add 10 mL of the prepared precursor solution to each reactor and perform a hydrothermal reaction at 180 °C for 6 hours. After the reaction, allow it to cool naturally to room temperature (25 °C), remove the sample, wash it sequentially with deionized water and anhydrous ethanol, and vacuum dry it at 50 °C for 24 hours to obtain a uniformly grown IS photoanode.

[0047] (3) Measure 150 mL of ultrapure water and place it in the reaction vessel. Then, add 2.61 g of potassium sulfate while stirring continuously until it is completely dissolved. Then, add 3.753 g of ferrous sulfate heptahydrate to the solution and purge with nitrogen gas for 20 minutes while stirring to ensure an oxygen-free environment. Finally, add 3.925 g of nickel nitrate hexahydrate and continue stirring for 20 minutes under a nitrogen atmosphere to finally form a homogeneous photoelectrochemical deposition electrolyte.

[0048] (4) The obtained IS photoanode was placed in a three-electrode system, with Ag / AgCl as the reference electrode and a platinum mesh as the counter electrode. The deposition process was carried out in the photoelectrochemical deposition electrolyte prepared above. After applying a constant potential (0 V relative to the Ag / AgCl electrode) and irradiating with standard sunlight for 10 minutes, an IS photoanode (denoted as IS-NF) with NiFeOOH loaded on the surface was obtained.

[0049] (5) The obtained IS-NF photoanode was placed in a three-electrode system, with Ag / AgCl as the reference electrode, a platinum mesh as the counter electrode, and 0.5 M Na2SO4 aqueous solution as the electrolyte. An external potential of 0.6 V (relative to Ag / AgCl) was applied under illumination, and the activation time was controlled at 40 seconds. The final sample (denoted as IS-NFA) was obtained.

[0050] The morphologies of IS, IS-NF, and IS-NFA electrodes are as follows: Figure 1 As shown. From Figure 1 As can be seen, IS exhibits a regular and smooth pyramidal geometry. After photoelectrochemical deposition, the IS-NF pyramidal surface is covered by a uniform NiFeOOH flocculent layer. After a brief photoelectrochemical activation treatment, the surface of IS-NFA evolves into a large number of abundant nanoporous structures, indicating that significant surface reconstruction occurred during the activation process. The formation of this structure originates from the leaching of sacrificial Ni elements and the in-situ construction of Fe-S anchoring bonds, which effectively enhances the chemical bonding force between the catalyst layer and the sulfide substrate, significantly improves the interfacial charge transport rate, and greatly reduces the interfacial recombination of photogenerated carriers.

[0051] The photoelectrodes prepared above were assembled into a photoelectrochemical cell, and their photocurrent performance was tested in a 0.5 M Na₂SO₄ solution. Figure 2 As shown, at 1.23 VRHE (relative to the reversible hydrogen electrode), the photocurrent density of the IS-NFA photoelectrode can reach 9.58 mA / cm². 2 The onset potential is approximately 0.005 VRHE, while the untreated IS electrode has a potential of only 1.72 mA / cm. 2 This demonstrates that the method described in this invention significantly improves the carrier separation efficiency of the photoanode and the surface OER kinetics.

[0052] Example 2:

[0053] The photoanode sample was prepared according to steps (1)-(5) of Example 1, except that the voltage for photoelectrochemical activation in step (5) was different. Figure 3The JV curves of the samples obtained at different activation potentials (0.4-0.8 V) are shown. Experimental results indicate that the photocurrent density of the obtained IS-NFA photoanode first increases and then decreases with increasing activation potential. The photocurrent response of IS-NFA reaches its peak at an activation potential of 0.6 V (relative to Ag / AgCl). This demonstrates that a suitable activation potential is crucial for triggering selective Ni leaching and driving interfacial reconstruction. An activation potential of 0.6 V enables the formation of optimal reconstruction and a strongly coupled catalytic interface between the co-catalyst layer and the substrate. Conversely, too low a potential leads to insufficient reconstruction kinetics, while too high a potential may cause excessive loss of the surface active layer, both of which are detrimental to maximizing PEC performance.

[0054] Example 3:

[0055] The IS-NFA photoelectrode was prepared according to the method of steps (1)-(5) in Example 1. The only difference was that the photoelectrochemical activation time in step (5) was adjusted. By controlling the activation time (20-60 seconds), IS-NFA photoelectrodes with different degrees of interface reconstruction were obtained.

[0056] The series of photoelectrodes prepared above were assembled into a photoelectrochemical cell, and its photochemical water splitting performance under different bias voltages was tested in 0.5 M Na₂SO₄ aqueous electrolyte. Figure 4 As shown, the PEC performance of the samples first increases and then decreases with increasing activation time. Experimental results show that the IS-NFA photoelectrode exhibits optimal catalytic activity when the activation time is 40 seconds: at a potential of 1.23 VRHE, its photocurrent density reaches 9.58 mA / cm², and the onset potential shifts significantly negatively to approximately 0.005 V relative to RHE (reversible hydrogen electrode). This indicates that a suitable activation time can precisely trigger the moderate leaching of Ni components and the in-situ recombination of Fe-S anchoring bonds, thereby constructing a self-optimized catalytic interface with minimal charge transport resistance and the most complete exposure of active sites. Insufficient activation time leads to incomplete interface reconstruction, while excessive activation time may cause excessive loss of surface active components, both of which are detrimental to improving PEC performance.

[0057] Effect evaluation:

[0058] This invention, based on a sacrificial metal-induced interface self-optimization strategy, realizes the transformation of co-catalysts from weakly coupled static contacts to strongly coupled dynamic interfaces, and has the following key technical points:

[0059] 1. Sacrificial Metal-Triggered Dynamic Interface Self-Optimization Mechanism: A photoelectrochemical (PEC) activation process is employed, utilizing the selective leaching of Ni components as a sacrificial trigger to drive the cocatalyst / semiconductor interface to spontaneously evolve from an initial static physical contact into a dynamically self-optimized heterojunction. This mechanism solves the scientific challenges posed by traditionally prepared cocatalysts, such as weak interfacial bonding, easy degradation, and inability to match reaction kinetics requirements in real time under operating conditions.

[0060] 2. Construction of Fe-S Strongly Coupled Anchor Bonds: Through the PEC reconstruction process, Fe species are driven to deeply chemically integrate with sulfur atoms on the sulfide substrate surface, forming stable Fe-S anchor bonds. This chemical bond acts as an "interface welder," transforming traditional point contacts into strongly chemically coupled contacts, significantly enhancing the charge transfer capacity and chemical stability of the interface.

[0061] 3. Dual Reconstruction-Driven Catalytic Microenvironment Remodeling: The activation process achieves a synergistic effect of morphological and chemical reconstruction. On the one hand, it induces porosification evolution on the sulfide surface, constructing a high specific surface area nanoporous structure to increase the exposure of active sites; on the other hand, it transforms the initial nickel-iron hydroxyl oxide into a highly dispersed, amorphous, iron-rich active outer layer. This synergistic effect together lowers the energy barrier of the oxygen evolution reaction.

[0062] 4. In-situ adaptive interface activation process: Under the synergistic effect of light irradiation and bias voltage, a leapfrog improvement in device performance is achieved through simple short-time electrochemical treatment. This "in-situ adaptive" approach not only simplifies the preparation process but also ensures that the modified layer can spontaneously adjust to the optimal catalytic coordination environment according to the actual operating potential.

[0063] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a nickel-iron / sulfide composite photoanode activated by sacrificial nickel-triggered reconstruction, characterized in that, Includes the following steps: S11: Under illumination, an indium sulfide photoanode is used as the working electrode for photoelectrochemical deposition to obtain an IS photoanode with NiFeOOH loaded on its surface; the electrolyte for the photoelectrochemical deposition includes water, potassium salt, iron salt and nickel salt; S12: Under illumination, the IS photoanode with NiFeOOH loaded on its surface is used as the working electrode for photoelectrochemical activation to obtain the nickel-iron / sulfide composite photoanode activated by sacrificial nickel triggering reconstruction; the electrolyte for photoelectrochemical activation includes water and sodium salt; the mass ratio of potassium salt, iron salt, nickel salt and water in the electrolyte for photoelectrochemical deposition is 2-3:2-4:2-4:140-160; the constant voltage used for photoelectrochemical deposition is -0.1 to 0.2 V, and the time is 5-15 min; the constant voltage used for photoelectrochemical activation is 0.4 V to 0.8 V, and the time is 20-60 s; the preparation method of the indium sulfide photoanode includes the following steps: S21: Mix indium salt and thiourea in water to obtain a precursor solution; S22: The precursor solution is hydrothermally reacted on the surface of fluorine-doped tin oxide conductive glass at 170-190°C for 5-7 h and then cooled to room temperature to obtain the indium sulfide photoanode; the mass ratio of the indium salt, thiourea and water is 1-3:1-2:180-220.

2. The preparation method according to claim 1, characterized in that: The potassium salt is potassium sulfate, the iron salt is ferrous sulfate, the nickel salt is nickel nitrate, and the sodium salt is sodium sulfate.

3. The preparation method according to claim 1, characterized in that: In steps S11 and S12, a three-electrode system is used for photoelectrochemical activation, with Ag / AgCl as the reference electrode and platinum mesh as the counter electrode.

4. A nickel-iron / sulfide composite photoanode prepared by the preparation method according to any one of claims 1-3, which utilizes sacrificial nickel to trigger reconstruction activation.

5. The application of the nickel-iron / sulfide composite photoanode activated by sacrificial nickel triggering in claim 4 in photoelectrochemical water splitting for hydrogen production.

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