Method for improving performance of a semiconductor metal semiconductor multilayer heterostructure photocathode

Abstract

The application relates to a method for improving the performance of a semiconductor metal semiconductor multilayer heterostructure light cathode, characterized in that a very thin metal layer is introduced between a p-type semiconductor light cathode and an n-type semiconductor light absorption layer, and then a catalyst is carried on the surface of the light cathode, so as to form a semiconductor metal semiconductor multilayer heterostructure high-performance light cathode. The method can be applied to common p-type semiconductor light cathodes such as p-Si, copper-zinc-tin-sulfur and the like, and can obviously improve the water decomposition hydrogen production performance of the light cathode, so that solar energy can be converted into chemical energy and stored.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photoelectrochemical water splitting devices, in particular to a method for improving the performance of a semiconductor metal semiconductor multilayer heterojunction photocathode. BACKGROUND

[0002] Solar energy utilization technology is an important way to achieve China's double carbon goal, and developing low-cost and large-scale solar energy utilization technology will be the focus of research in China in the coming period. Photovoltaic cells can directly convert solar energy into electrical energy, but due to factors such as day and night and rain, they cannot continuously supply energy. Converting solar energy into hydrogen energy for storage can effectively solve the problem of large-scale solar energy storage. Developing high-performance semiconductor photocathode water splitting to produce hydrogen is an effective way to solve this problem. Traditional semiconductor photocathodes generally use heterojunction construction to improve their performance, with the construction of type II heterojunction being a common method, but there is still a big gap from the theoretical efficiency, so a semiconductor metal semiconductor multilayer heterojunction photocathode performance improvement method is needed to solve the above problems. SUMMARY

[0003] The purpose of the present application is to provide a semiconductor metal semiconductor multilayer heterojunction photocathode performance improvement method to solve the above problems in the prior art.

[0004] In order to achieve the above purpose, the present application provides the following technical scheme:

[0005] A semiconductor metal semiconductor multilayer heterojunction photocathode performance improvement method includes a p-type pyramid silicon-based photocathode and a copper-zinc-tin-sulfur (CZTS) based photocathode.

[0006] The p-type pyramid silicon-based photocathode includes a p-Si semiconductor, a metal Ti layer, an n-type semiconductor light-absorbing layer CdS, and a noble metal catalyst Pt.

[0007] The CZTS-based photocathode includes a CZTS semiconductor, a metal Ni layer, an n-type semiconductor light-absorbing layer CdS, and a noble metal catalyst Pt.

[0008] In another embodiment of the present application, the Ti metal layer is deposited on the pyramid p-Si surface by ion sputtering physical vapor deposition method, CdS is deposited by chemical bath deposition method, and Pt catalyst is loaded on the pyramid p-Si photocathode by photoelectrodeposition method to successfully prepare.

[0009] In still another embodiment of the present application, the method for preparing CZTS-based photo-cathode comprises the following steps:

[0010] In still another embodiment of the present application, the method for preparing p-type pyramid silicon-based photo-cathode comprises the following steps:

[0011] Step one, packaging the pyramid p-Si wafer, cutting the pyramid p-Si wafer into appropriate size, sealing 2 / 3 area of the back of the p-Si wafer with 704 silicone rubber, and coating the edge of the silicon wafer with silicone rubber, and drying for standby;

[0012] Step two, configuring the solution required for chemical bath deposition of CdS: dissolving 0.015M CdSO4 in deionized water as precursor solution 1; dissolving 1.5M thiourea in deionized water as precursor solution 2; and 36%-38% ammonia water as precursor solution 3;

[0013] Step three, removing the surface oxide layer of the pyramid p-Si: immersing the silicon in 5% HF solution for 30 seconds to remove the surface SiOx layer;

[0014] Step four, ion sputtering deposition of metal Ti: placing the HF treated p-Si into the sputtering chamber of ion sputtering instrument Cressington 208HR for sputtering and preservation;

[0015] Step five, chemical bath deposition of CdS: the precursor solution for chemical bath deposition of CdS is 36mL deionized water, 0.015M CdSO4 solution 5mL, 1.5M thiourea solution 2.5mL, and 36%-38% ammonia water 6.5mL, which are collectively added into a beaker to obtain 50mL of precursor solution, and the temperature of the oil bath is set to 70℃; the p-Si is clamped with a clamp and immersed in the precursor solution, and finally the beaker is placed in the oil bath at 70℃ and gently stirred for 12min; then the silicon wafer is washed with deionized water and dried with nitrogen, and is sealed for preservation;

[0016] Step six, photo-electrodeposition of Pt catalyst: the deposition solution is a mixed solution of 1mM H2PtCl6+0.1M Na2SO4; the photo-cathode is placed under AM1.5 light irradiation condition, the deposition potential is-0.2VRHE, and the deposition amount is 30mC / cm2, and the p-Si-based semiconductor metal semiconductor multilayer heterostructure high-performance photo-cathode is successfully prepared.

[0017] In still another embodiment of the present application, the method for preparing CZTS-based photo-cathode comprises the following steps:

[0018] Step 1: Prepare the precursor solution for spin-coating CZTS: Dissolve 2.4785g thiourea and 0.7405g cuprous chloride in 4mL dimethyl sulfoxide (DMSO) as precursor solution 1; dissolve 1.042g tin tetrachloride, 0.7046g zinc acetate, and 0.1759g cadmium chloride in 4mL DMSO as precursor solution 2; then mix precursor solution 1 and precursor solution 2 and stir thoroughly.

[0019] Step 2: Spin coating to prepare CZTS semiconductor thin films: In an argon-filled glove box, drop the precursor solution onto molybdenum glass and spin coat at 2000 rpm for 60 seconds. After spin coating, transfer the sample to a hot plate at 370°C and calcine for 90 seconds, then cool. Repeat the above steps several times to obtain a thin film of suitable thickness.

[0020] Step 3, film curing: The spin-coated sample and 100mg of high-purity sulfur powder are placed in a ceramic boat and transferred to a rapid heating tube furnace. Before heating, the tube furnace needs to be purged with argon three times. Then, the temperature is increased from 0 to 600℃ and held for 15 minutes. After that, it is allowed to cool naturally to room temperature. Curing is complete.

[0021] Step 4: Ion sputtering deposition of metallic Ni: The prepared CZTS thin film is placed in the sputtering chamber of the Cressington 208HR ion sputtering instrument for sputtering;

[0022] Step 5, Chemical Bath Deposition of CdS: The precursor solution for chemical bath deposition of CdS is 36 mL.

[0023] 5 mL of deionized water, 0.015 M dSO4 solution, 2.5 mL of 1.5 M thiourea solution, and 6.5 mL of 36%-38% ammonia solution were added together to a beaker to obtain a 50 mL precursor solution. The oil bath temperature was set to 60 °C. The CZTS was clamped and immersed in the precursor solution. Finally, the beaker was placed in the 60 °C oil bath and gently stirred for 5 min. Then, it was rinsed with deionized water, dried with nitrogen, and sealed for storage.

[0024] Step 6: Ion sputtering deposition of noble metal catalyst Pt: The prepared CZTS / Ni / CdS thin film is placed in the sputtering chamber of the Cressington 208HR ion sputtering instrument. After sputtering, the sample is taken out and sealed for preservation.

[0025] In another embodiment of the present invention, the illumination condition is an AM1.5G (100mWcm-2) solar simulator as the light source.

[0026] In still another embodiment of the present application, in the step six, the purity of the Pt target material used as the metal source is 99.99%, the working current of the sputtering instrument is adjusted to 20 mA, the rotary table is opened after high-purity Ar is passed, the sputtering duration is set to 25 s, and after 25 s of sputtering, the sputtering instrument is closed after waiting for 30 s, the sample is taken out and sealed for storage.

[0027] In still another embodiment of the present application, in the step six, the purity of the Pt target material used as the metal source is 99.99%, the working current of the sputtering instrument is adjusted to 20 mA, the rotary table is opened after high-purity Ar is passed, the sputtering duration is set to 25 s, and after 25 s of sputtering, the sputtering instrument is closed after waiting for 30 s, the sample is taken out and sealed for storage.

[0028] In the above technical solution, the present application provides a method for improving the performance of a semiconductor metal semiconductor multilayer heterostructure light cathode. Figures 1-11 As shown in the accompanying drawings, (1) the present application is inspired by the electron transport chain structure in natural light and action, and adopts p-Si and CZTS as the light cathode to construct a semiconductor metal semiconductor multilayer heterostructure, which has a significantly improved water decomposition efficiency compared with the traditional type II heterojunction. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments described in the present application, and other accompanying drawings can also be obtained by those skilled in the art based on these drawings.

[0030] Figure 1 The accompanying drawings are schematic diagrams of the high-performance light cathode structure of the semiconductor metal semiconductor multilayer heterostructure.

[0031] Figure 2 The accompanying drawings are light-dark state current chopping curves of p-Si / CdS / Pt and p-Si / Ti / CdS / Pt.

[0032] Figure 3 The accompanying drawings are half-cell efficiency (ABPE) diagrams of p-Si / CdS / Pt and p-Si / Ti / CdS / Pt.

[0033] Figure 4 The accompanying drawings are SEM diagrams of the pyramid p-Si surface.

[0034] Figure 5 The accompanying drawings are ICP-OES diagrams of the Ti element of the pyramid p-Si / CdS and p-Si / Ti / CdS light cathode.

[0035] Figure 6 SEM images of p-Si / CdS (a) and p-Si / Ti / CdS (b) for 12 min of CdS deposition by chemical bath.

[0036] Figure 7 SEM images of p-Si / CdS (a) for 9 min of CdS deposition and p-Si / CdS (b) for 12 min of CdS deposition using low concentration precursor solution.

[0037] Figure 8 Optoelectronic properties of p-Si / CdS-9min / Pt (a) and p-Si / Ti / CdS-12min / Pt (b) and p-Si / CdS-12min / Pt for CdS deposition using low concentration precursor solution.

[0038] Figure 9 Light on-dark off linear voltammetry scan and light on-dark off time-current curves of CZTS / CdS / Pt and CZTS / Ni / CdS / Pt.

[0039] Figure 10 Half-cell efficiency (ABPE) plots of CZTS / Ni / CdS / Pt and CZTS / CdS / Pt.

[0040] Figure 11 SEM images of CZTS / CdS (a) and CZTS / Ni / CdS (b). DETAILED DESCRIPTION

[0041] The semiconductor metal semiconductor multilayer heterostructure photocathode used in the present application is characterized in that the semiconductor I is a p-type pyramid silicon or a CZTS semiconductor, the metal layer is prepared by physical vapor deposition method of ion sputtering, the semiconductor II is generally a wide band gap semiconductor light absorbing layer (CdS), and the outermost layer is a catalyst layer, which is generally a Pt noble metal catalyst.

[0042] Please refer to Figure 1 , a schematic diagram of the high-performance semiconductor metal semiconductor multilayer heterostructure photocathode structure.

[0043] The present application will be further described in detail below in combination with examples and drawings.

[0044] Example 1

[0045] In this embodiment, the metal Ti is deposited by ion sputtering, the CdS is grown by chemical bath deposition, and the Pt is loaded on the surface of the photoelectrode by photoelectrodeposition as a p-Si / Ti / CdS / Pt photoelectrode. The Ag / AgCl is used as a reference electrode, the carbon rod is used as a counter electrode, and the electrolyte is a neutral mixed solution containing 0.5M dipotassium hydrogen phosphate and 0.5M monopotassium hydrogen phosphate with pH = 7, which together constitute a three-electrode measurement system. The p-Si / CdS / Pt does not have the step of sputtering Ti metal in the preparation process, and the other preparation processes are the same.

[0046] Please refer to Figure 2 The light state-dark state current chopping curve of p-Si / CdS / Pt and p-Si / Ti / CdS / Pt is shown in

[0047] Please refer to Figure 3 The half-cell efficiency of p-Si / Ti / CdS / Pt can reach 3.06%, which is twice the half-cell efficiency of p-Si / CdS / Pt.

[0048] The photoelectrode preparation method comprises the following steps:

[0049] Step one, package the pyramid p-Si sheet, cut the pyramid p-Si sheet into a suitable size (generally 1*2 cm), seal 2 / 3 of the area of the back of the p-Si with 704 silicone rubber, and coat the edge of the silicon wafer with silicone rubber, and dry for standby.

[0050] Step two, configure the solution required for chemical bath deposition of CdS: dissolve 0.015M CdSO4 in deionized water as precursor solution 1; dissolve 1.5M thiourea in deionized water as precursor solution 2; and 36%-38% ammonia water as precursor solution 3.

[0051] Step three, remove the surface oxide layer of the pyramid p-Si: immerse the silicon in 5% HF solution for 30 seconds to remove the surface SiOx layer.

[0052] Please refer to Figure 4 The surface of the p-Si is in the shape of a pyramid.

[0053] Step four, ion sputtering deposition of metal Ti: Put the HF treated p-Si into the sputtering chamber of ion sputtering instrument Cressington 208HR, use Ti target with purity of 99.99% as metal source, adjust the working current of sputtering instrument to 20 mA, open the rotating table after passing high-purity Ar, set the sputtering time to 35 s, and then wait for 30 s after 35 s of sputtering to close the sputtering instrument, take out the sample and seal the sample for storage.

[0054] See Figure 5 The Ti content of the p-Si / Ti / CdS / Pt photocathode can be accurately measured by ICP-OES, and the titanium content of the p-Si / Ti / CdS / Pt photocathode is 0.059 μg / cm2, and the titanium content in the p-Si / CdS / Pt is 0.003 μg / cm2, which can be ignored.

[0055] Step five, chemical bath deposition of CdS: The precursor solution for chemical bath deposition of CdS is 36 mL of deionized water, 5 mL of 0.015M CdSO4 solution, 2.5 mL of 1.5M thiourea solution, and 6.5 mL of 36%-38% ammonia water, which are added together in a beaker to obtain 50 mL of precursor solution, and the oil bath temperature is set to 70°C; the p-Si is clamped with a clamp and immersed in the precursor solution, and finally the beaker is placed in the 70°C oil bath and gently stirred for 12 min; then the silicon wafer is washed with deionized water and dried with nitrogen, and sealed for storage.

[0056] See Figure 6 , respectively, the SEM surface diagram of p-Si / CdS(a) and p-Si / Ti / CdS(b) for chemical bath deposition of CdS for 12 minutes, and the CdS deposition density on the surface of p-Si / CdS is much higher than that of p-Si / Ti / CdS.

[0057] See Figure 7 , respectively, SEM of p-Si / CdS(a) with 9 min of CdS deposition and p-Si / CdS(b) with 12 min of CdS deposition using a low concentration precursor solution, and the CdS density is similar to that of p-Si / Ti / CdS-12min.

[0058] See Figure 8 The above three kinds of control CdS deposition density are similar, but the photoelectrochemical performance is obviously different, and the photoelectrochemical performance of p-Si / Ti / CdS-12min / Pt is the best, so the CdS deposition density is not the main factor causing the photoelectric performance of p-Si / CdS / Pt and p-Si / Ti / CdS / Pt photocathode.

[0059] Step six, photoelectrodeposition of Pt catalyst: the deposition solution is a mixed solution of 1 mM H2PtCl6+0.1 M Na2SO4; the photoelectrode is placed under AM1.5 light, the deposition potential is -0.2 V RHE, and the deposition amount is 30 mC / cm2, and a p-Si-based semiconductor metal semiconductor multilayer heterojunction high-performance photoelectrode is successfully prepared.

[0060] Silicon-based photoelectrode

[0061] When an AM1.5G (100 mWcm-2) solar light simulator is used as a light source, the hydrogen production onset potential is 0.42 V RHE, the hydrogen production current density reaches saturation at 0.15 V RHE, the hydrogen production current density is 18 mA / cm2 at 0 V RHE, the half-cell efficiency can reach 3.06%, and the photoelectrochemical performance of the silicon-based semiconductor metal semiconductor multilayer heterojunction photoelectrode is obviously improved compared with the p-Si / CdS / Pt type II heterojunction photoelectrode.

[0062] Example 2

[0063] In this embodiment, a CZTS semiconductor is prepared by a spin-coating calcination method, a metal Ni layer is deposited by ion sputtering, CdS is deposited by a chemical bath, and finally a noble metal catalyst Pt is deposited by ion sputtering, and a CZTS / Ni / CdS / Pt photoelectrode is prepared by the above steps. An Ag / AgCl electrode is used as a reference electrode, a carbon rod is used as a counter electrode, and an electrolyte is a neutral mixed solution containing 0.5 M dipotassium hydrogen phosphate and 0.5 M potassium dihydrogen phosphate with pH = 7, which together form a three-electrode measurement system. The CZTS / CdS / Pt does not have the step of sputtering a metal Ni layer in the preparation process, and the other preparation processes are the same.

[0064] See Figure 9 , the light state-dark state linear voltammetry scan curves and the light state-dark state time-current curves of the CZTS / CdS / Pt and the CZTS / Ni / CdS / Pt, the hydrogen production onset potential of the CZTS / Ni / CdS / Pt is 0.6 V RHE, and the current density reaches 14.5 mA / cm2 at 0 V RHE, while the current density of the CZTS / CdS / Pt is 11.5 mA / cm2 at 0 V RHE, and the photocurrent of the photoelectrode is obviously increased after adding the metal Ni intermediate layer.

[0065] See Figure 10 The half-cell efficiency of the CZTS / Ni / CdS / Pt can reach 2.87%, while the half-cell efficiency of the CZTS / CdS / Pt is 2.35%, and the half-cell efficiency of the photoelectrode is also increased after adding the metal Ni intermediate layer.

[0066] The photoelectrode preparation method comprises the following steps:

[0067] Step one, configuration of precursor solution for spin-coating CZTS: 2.4785 g of thiourea and 0.7405 g of cuprous chloride were dissolved into 4 mL of dimethyl sulfoxide (DMSO) as precursor solution 1; 1.042 g of tin tetrachloride, 0.7046 g of zinc acetate, and 0.1759 g of cadmium chloride were dissolved into 4 mL of DMSO as precursor solution 2; then the precursor solution 1 and the precursor solution 2 were mixed and stirred thoroughly. The element molar ratio was Cu / (Zn+Cd+Sn)=0.85, (Zn+Cd) / Sn=1.2, and Cd / (Zn+Cd)=0.2.

[0068] Step two, preparation of CZTS semiconductor thin film by spin-coating method: in an argon-filled glove box, the precursor solution was dropped on a molybdenum glass, and a spin coater was used to spin at a speed of 2000 rpm for 60 seconds; after the spin-coating was completed, the sample was transferred to a hot stage at 370°C for calcination for 90 seconds and then cooled; the above steps were repeated seven times to obtain a thin film with a suitable thickness.

[0069] Step three, thin film sulfuration: the sample prepared by spin-coating was placed in a porcelain boat together with 100 mg of high-purity sulfur powder and transferred to a rapid heating tube furnace; before heating, the tube furnace was purged with argon three times, then heated to 600°C and kept for 15 minutes, and then naturally cooled to room temperature, and the sulfuration was completed.

[0070] Step four, ion sputtering deposition of metal Ni: the prepared CZTS thin film was placed in the sputtering chamber of an ion sputtering instrument Cressington 208HR, a Ni target with a purity of 99.99% was used as the metal source, the working current of the sputtering instrument was adjusted to 20 mA, high-purity Ar was introduced, the rotary table was opened, the sputtering time was set to 40 s, and then after 40 s of sputtering, the sputtering instrument was closed after waiting for 30 s, and the CZTS / CdS did not need this step.

[0071] Step five, chemical bath deposition of CdS: the precursor solution for chemical bath deposition of CdS was 36 mL of deionized water, 5 mL of 0.015M CdSO4 solution, 2.5 mL of 1.5M thiourea solution, and 6.5 mL of 36%-38% ammonia water, which were added together into a beaker to obtain 50 mL of precursor solution, and the temperature of the oil bath was set to 60°C; the CZTS was clamped with a clamp and immersed into the precursor solution, and finally the beaker was placed in an oil bath at 60°C and gently stirred for 5 min; then it was washed with deionized water and dried with nitrogen, and sealed for preservation.

[0072] See Figure 11 , SEM images of CZTS / CdS (a) and CZTS / Ni / CdS (b).

[0073] Step six, ion sputtering deposition of noble metal catalyst Pt: the prepared CZTS / Ni / CdS thin film is placed into the sputtering chamber of ion sputtering instrument Cressington 208HR, a Pt target with a purity of 99.99% is used as a metal source, the working current of the sputtering instrument is adjusted to 20 mA, after high-purity Ar is passed, the rotating table is opened, the sputtering time is set to 25 s, and after 25 s of sputtering, the sputtering instrument is closed after waiting for 30 s, the sample is taken out and sealed for storage.

[0074] CZTS-based semiconductor metal semiconductor multilayer heterostructure photocathode, AM1.5G (100 mW cm-2) solar light simulator as light source,

[0075] The half-cell efficiency of CZTS / Ni / CdS / Pt can reach 2.87%, while the half-cell efficiency of CZTS / CdS / Pt is 2.35%;

[0076] The hydrogen production onset potential of CZTS / Ni / CdS / Pt is 0.6 VRHE, and the current density at 0 VRHE reaches 14.5 mA / cm2, while the current density of CZTS / CdS / Pt at 0 VRHE is 11.5 mA / cm2;

[0077] Compared with the type II heterojunction photocathode of CZTS / CdS / Pt, the photoelectrochemical performance of the semiconductor metal semiconductor multilayer heterostructure photocathode is obviously improved.

[0078] Example 3

[0079] In another embodiment of the application, in a three-electrode system, under sunlight, photo-generated electrons are transferred to the electrolyte according to the direction of the semiconductor, metal, semiconductor / catalyst electron transfer chain, realizing efficient separation of photo-generated electrons and holes, and reduction reaction of H+ in the electrolyte to produce hydrogen, and the holes are transferred to the counter electrode to occur oxygen evolution reaction; the three-electrode system is a working electrode, a carbon rod counter electrode, and an Ag / AgCl reference electrode, and the electrolyte is a neutral mixed solution with pH=7.

[0080] The above only describes some exemplary embodiments of the application by way of illustration, and it is needless to say that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the application. Therefore, the above figures and description are illustrative in nature and should not be understood as limiting the scope of protection of the claims of the application.

Claims

1. A method for improving photocathode performance using a semiconductor-metal-semiconductor multilayer heterostructure, characterized in that, Including p-type pyramid silicon-based photocathodes; The p-type pyramid silicon-based photocathode comprises a p-Si semiconductor, a Ti metal layer, an n-type semiconductor light-absorbing layer CdS, and a noble metal catalyst Pt; Pt was supported on the surface of a photocathode using photoelectrode deposition to serve as a p-Si / Ti / CdS / Pt photoelectrode, with Ag / AgCl as the reference electrode and a carbon rod as the counter electrode.

2. The method for improving photocathode performance using a semiconductor-metal-semiconductor multilayer heterostructure according to claim 1, characterized in that, A Ti metal layer was deposited on a pyramidal p-Si surface using a physical vapor deposition method involving ion sputtering.

3. The method for improving photocathode performance using a semiconductor-metal-semiconductor multilayer heterostructure according to claim 1, characterized in that, The fabrication of the p-type pyramid silicon-based photocathode includes the following steps: Step 1: Encapsulate the pyramid p-Si wafer. Cut the pyramid p-Si wafer to the appropriate size, seal 2 / 3 of the back side of the p-Si wafer with 704 silicone rubber, and apply silicone to the edges of the wafer. Let it dry for later use. Step 2: Prepare the solution required for chemical bath deposition of CdS: CdSO4 was dissolved in deionized water to prepare a 0.015M solution as precursor solution 1; Thiourea was dissolved in deionized water to prepare a 1.5M solution as precursor solution 2; ammonia solution with a mass fraction of 36%-38% was used as precursor solution 3. Step 3: Remove the oxide layer on the surface of the pyramidal p-Si: Silicon was immersed in a 5% HF solution for 30 seconds to remove SiO2 from the surface. X layer; Step 4: Ion sputtering deposition of metallic Ti: The HF-treated p-Si was sputtered in the sputtering chamber of the Cressington 208HR ion sputtering instrument and then stored. Step 5: Chemical bath deposition of CdS: The precursor solution for chemical bath deposition of CdS consisted of 36 mL of deionized water, 5 mL of 0.015 M CdSO4 solution, 2.5 mL of 1.5 M thiourea solution, and 6.5 mL of 36%-38% ammonia solution, all added together to a beaker to obtain 50 mL of precursor solution. The oil bath temperature was set to 70 °C. The p-Si was clamped and immersed in the precursor solution. Finally, the beaker was placed in an oil bath at 70°C and the reaction was gently stirred for 12 minutes. Then remove the silicon wafer, rinse it with deionized water, dry it with nitrogen, and seal it for storage; Step 6: Photoelectrochemical deposition of Pt catalyst: The deposition solution was a mixed solution of 1 M M H2PtCl6 + 0.1 M Na2SO4; When the photocathode is placed under AM1.5 illumination, the deposition potential is -0.2VRHE, and the deposition amount is 30 mc / cm. 2 A high-performance photocathode with a p-Si-based semiconductor-metal-semiconductor multilayer heterostructure has been successfully fabricated.

4. The method for improving photocathode performance using a semiconductor-metal-semiconductor multilayer heterostructure according to claim 3, characterized in that, Lighting conditions: AM1.5G, 100mw / cm² 2 A sunlight simulator is used as a light source.

5. The method for improving photocathode performance using a semiconductor-metal-semiconductor multilayer heterostructure according to claim 3, characterized in that, When sputtering Ti by ion sputtering, a Ti target with a purity of 99.99% is used as the metal source. The operating current of the sputtering instrument is adjusted to 20mA. After passing high-purity Ar, the rotating stage is turned on. The sputtering time is set to 35-40s. After 35-40 seconds of sputtering, wait another 30 seconds to turn off the sputtering instrument, take out the sample, and seal and store the sample.

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