Silicon-based photoelectrocatalytic material and preparation method and application thereof

Abstract

The present invention discloses a silicon-based photoelectrocatalytic material and a preparation method and application thereof, belonging to the technical field of photoelectrocatalytic materials. The silicon-based photoelectrocatalytic material comprises a silicon substrate, the silicon substrate has a relative polished surface and a non-polished surface, the surface of the polished surface is deposited with nickel metal nanoparticles, and the surface of the non-polished surface is provided with an insulating layer. The silicon-based photoelectrocatalytic material has high catalytic performance and high saturated photocurrent of photoelectrocatalytic water decomposition. The preparation method thereof is simple and easy to operate. When it is used for photoelectrocatalytic water decomposition, it shows a high saturated photocurrent of photoelectrocatalytic water decomposition.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectrocatalytic materials, and in particular to a silicon-based photoelectrocatalytic material and a preparation method and application thereof. Background Art

[0002] Energy crisis and environmental issues have become one of the urgent problems to be solved in the development and progress of contemporary mankind. How to find a green, environmentally friendly and sustainable way to alleviate energy shortage and environmental pressure is the common vision of researchers around the world.

[0003] Photoelectrocatalytic (PEC) water decomposition is mainly based on semiconductor materials. It uses solar energy to convert water (H 2 O) decomposes into hydrogen energy (H 2 ) and oxygen (O 2 ), which not only utilizes green energy (solar energy), but also alleviates energy and environmental pressures.

[0004] However, the metal-insulator-semiconductor (MIS) structure currently used in PEC still has the problems of high over potential and low saturation photocurrent.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] One of the objectives of the present invention is to provide a silicon-based photoelectrocatalytic material to solve at least one of the above-mentioned technical problems.

[0007] A second object of the present invention is to provide a method for preparing the above-mentioned silicon-based photoelectrocatalytic material.

[0008] The third object of the present invention is to provide an application of the above-mentioned silicon-based photoelectrocatalytic material.

[0009] This application can be implemented as follows:

[0010] In a first aspect, the present application provides a silicon-based photoelectrocatalytic material, which includes a silicon substrate having a relative polished surface and a non-polished surface, the surface of the polished surface is deposited with nickel metal nanoparticles, and the surface of the non-polished surface is provided with an insulating layer.

[0011] In an optional embodiment, the silicon substrate has at least one of the following features:

[0012] Feature A: has (100) crystal orientation;

[0013] Feature B: resistance is 1-5Ω·cm;

[0014] Feature C: The silicon substrate is an N-type silicon wafer or a P-type silicon wafer.

[0015] In an alternative embodiment, the particle size of the nickel metal nanoparticles is 20-40 nm.

[0016] In a second aspect, the present application provides a method for preparing a silicon-based photoelectrocatalytic material as described in any of the aforementioned embodiments, comprising the following steps: setting an insulating layer on the surface of the non-polished surface of the silicon substrate, and depositing nickel metal nanoparticles on the surface of the polished surface of the silicon substrate.

[0017] In an optional embodiment, after an insulating layer is disposed on the surface of the non-polished surface of the silicon substrate, nickel metal nanoparticles are deposited on the surface of the polished surface of the silicon substrate.

[0018] In an optional embodiment, constant current electrodeposition is used to deposit nickel metal nanoparticles on the polished surface of the silicon substrate.

[0019] In an optional embodiment, the deposition current is 1-5 mA, and the deposition time is 1-5 s.

[0020] In an optional embodiment, the component of the electrolyte used for deposition includes a nickel source, and / or the electrode system used for deposition is a three-electrode system.

[0021] In an alternative embodiment, the nickel source includes at least one of nickel sulfate hexahydrate, nickel chloride, and nickel nitrate.

[0022] In an optional embodiment, the electrolyte solution further comprises a pH adjuster.

[0023] In an alternative embodiment, the pH adjusting agent comprises boric acid.

[0024] In an optional embodiment, the concentration of the nickel source contained in the electrolyte is 0.04-0.06 mol / L.

[0025] In an optional embodiment, the counter electrode in the three-electrode system is a platinum electrode, and / or the reference electrode in the three-electrode system is a saturated calomel electrode.

[0026] In an alternative embodiment, the insulating layer is an epoxy resin attached to the non-polished surface of the silicon substrate.

[0027] In an optional implementation, before providing the insulating layer, the silicon substrate is also pre-processed.

[0028] In an optional embodiment, the pre-treatment includes removing impurities on the surface of the silicon substrate.

[0029] In an optional embodiment, the pre-treatment further includes preparing the silicon substrate from which impurities have been removed into an electrode.

[0030] In an optional embodiment, the pre-treatment further includes etching the prepared electrode.

[0031] In an optional embodiment, the etching solution used for etching is a hydrofluoric acid solution; and / or, the thickness of the oxide layer of the silicon substrate after etching is 2-6 nm.

[0032] In an optional embodiment, the method further comprises mixing the sample after depositing nickel metal nanoparticles with an iron-containing solution.

[0033] In an alternative embodiment, the iron-containing solution is a ferrous sulfate solution.

[0034] In a third aspect, the present application provides an application of a silicon-based photoelectrocatalytic material according to any of the aforementioned embodiments, wherein the silicon-based photoelectrocatalytic material is used for photoelectrocatalytic water decomposition.

[0035] The beneficial effects of this application include:

[0036] The present application forms a metal-insulator-semiconductor (MIS) structure by depositing nickel metal nanoparticles on the polished surface of a silicon substrate and setting an insulating layer on the non-polished surface. The nickel metal nanoparticles act as a catalyst in the photoelectrocatalytic reaction. The nickel metal exists in the form of particles rather than thin film layers, which is conducive to making the silicon-based photoelectrocatalytic material have higher catalytic performance and higher saturated photocurrent of photoelectrocatalytic water decomposition.

[0037] The preparation method of the silicon-based photoelectrocatalytic material is simple and easy to operate.

[0038] When used in photoelectrocatalytic water splitting, it can have a lower turn-on voltage and a higher saturation photocurrent for photoelectrocatalytic water splitting. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 The 2mA-2s sample in Experiment 1 was in 1M NaOH solution, 100mW / cm 2 Oxygen evolution polarization curves under illumination and without illumination;

[0041] Figure 2 The 2mA-2s sample in Experiment 1 was in 1M NaOH solution, 100mW / cm 2 Photoresponse oxygen evolution polarization curve under illumination;

[0042] Figure 3 The different samples in Experimental Example 1 were subjected to 1M NaOH solution and 100mW / cm 2 Oxygen evolution polarization curve under illumination;

[0043] Figure 4 The oxygen evolution polarization curve of the 2mA-2s sample in Experimental Example 1 under different light densities;

[0044] Figure 5 The 1mA-2s sample in Experiment 1 and its immersion in FeSO 4 7H 2 O solution for 3 h, in the absence of light and at 100 mW / cm 2 Oxygen evolution polarization curve under illumination;

[0045] Figure 6 The 4mA-2s sample in Experiment 1 and its immersion in FeSO 4 7H 2 O solution for 3 h, in the absence of light and at 100 mW / cm 2 Oxygen evolution polarization curve under illumination;

[0046] Figure 7 The 2mA-2s sample in Experiment 1 was subjected to 100mW / cm 2 Photoresponse hydrogen evolution polarization curve under illumination;

[0047] Figure 8 The 2mA-2s sample in Experiment 1 was subjected to 0.65M NaOH, 0.35M LiOH and 2M HBO 3 In the mixed solution at 100mW / cm 2 Oxygen evolution stability test results under light;

[0048] Fig. 9 This is the SEM result of the 2mA-2s sample obtained in Example 1 of Experimental Example 3 without immersion treatment;

[0049] Fig.10 This is the SEM result of the 2mA-2s sample obtained in Example 5 of Experimental Example 3 after immersion treatment. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0051] The silicon-based photoelectrocatalytic material provided in this application and its preparation method and application are described in detail below.

[0052] The present application proposes a silicon-based photoelectrocatalytic material, which includes a silicon substrate having a relative polished surface and a non-polished surface, the surface of the polished surface is deposited with nickel metal nanoparticles, and the surface of the non-polished surface is provided with an insulating layer.

[0053] Silicon (Si) has the advantages of abundant content, low preparation cost and suitable bandgap width (Eg = 1.12eV), which makes it have great research value and application prospects in PEC. At the same time, the oxide layer of the silicon wafer itself is also a "natural" insulating layer, which provides a good guarantee for building MIS structure and protecting the stability of the device.

[0054] In the present application, the silicon substrate may exemplarily have at least one of the following features:

[0055] Feature A: has (100) crystal orientation;

[0056] Feature B: resistance is 1-5Ω·cm;

[0057] Feature C: The silicon substrate is an N-type silicon wafer or a P-type silicon wafer.

[0058] Among them, setting the resistance value to 1-5Ω·cm can make it have a good metal-semiconductor contact effect. If the resistance value is too high, the resistance will be too large, which is not conducive to electron transmission; if the resistance value is too low, it will lead to a large leakage current, resulting in mainly electrocatalysis rather than photocatalysis.

[0059] When the silicon substrate is an N-type silicon wafer, it is mainly used for oxygen evolution reaction; when the silicon substrate is a P-type silicon wafer, it is mainly used for hydrogen evolution reaction.

[0060] In the present application, the nickel metal nanoparticles deposited on the polished surface of the silicon substrate act as a catalyst in the photoelectrocatalytic reaction, and the particle size is 20-40nm, such as 20nm, 22nm, 25nm, 28nm, 30nm, 32nm, 35nm, 38nm or 40nm, etc., and can also be any other value within the range of 20-40nm.

[0061] It should be noted that in the prior art, when a silicon substrate is used as a base to realize photoelectrocatalytic water splitting with nickel-based materials as the main material, a nickel thin film layer is deposited on the polished surface of the silicon substrate.

[0062] The present application can have higher catalytic performance by depositing a non-thin film layer of nickel metal nanoparticles on the surface of the polished surface of the silicon substrate, and can obtain a lower turn-on voltage and a higher saturation photocurrent of photoelectrocatalytic water decomposition.

[0063] Correspondingly, the present application also provides a method for preparing the above-mentioned silicon-based photoelectrocatalytic material, comprising the following steps: setting an insulating layer on the surface of the non-polished surface of the silicon substrate, and depositing nickel metal nanoparticles on the surface of the polished surface of the silicon substrate.

[0064] Specifically, an insulating layer may be firstly provided on the surface of the non-polished surface of the silicon substrate, and then nickel metal nanoparticles may be deposited on the surface of the polished surface of the silicon substrate.

[0065] It should be noted that, at present, the preparation process used for MIS structure is relatively complex and costly, which is not conducive to its large-scale production and preparation.

[0066] The present application creatively adopts a constant current electrodeposition method to deposit nickel metal nanoparticles on the surface of the polished surface of a silicon substrate, which not only greatly simplifies the preparation process and reduces the preparation cost, but also ensures that the prepared silicon-based photoelectrocatalytic material has a lower turn-on voltage and a higher saturation photocurrent for photoelectrocatalytic water decomposition.

[0067] For reference, the deposition current is 1-5 mA, such as 1 mA, 2 mA, 3 mA, 4 mA, 5 mA, etc. It can also be any other value within the range of 1-5 mA, preferably 2 mA.

[0068] If the deposition current is too large, it will easily poison the catalyst; if the deposition current is too small, the amount of deposited catalyst will be insufficient.

[0069] The deposition time may be 1-5 s, such as 1 s, 1.5 s, 2 s, 2.5 s, 3 s, 3.5 s, 4 s, 4.5 s or 5 s, etc., or any other value within the range of 1-5 s, preferably 2 s.

[0070] The composition of the electrolyte used for deposition includes a nickel source.

[0071] Illustratively, the nickel source may include at least one of nickel sulfate hexahydrate, nickel chloride, and nickel nitrate.

[0072] Furthermore, the electrolyte solution also includes a pH adjuster, such as boric acid.

[0073] Preferably, the concentration of the nickel source contained in the electrolyte is 0.04-0.06 mol / L, such as 0.04 mol / L, 0.045 mol / L, 0.05 mol / L, 0.055 mol / L or 0.06 mol / L, etc., and can also be any other value within the range of 0.04-0.06 mol / L.

[0074] Taking the concentration of nickel source contained in the electrolyte as 0.05 mol / L as an example, the electrolyte can be prepared in the following manner:

[0075] 6.57125 g of nickel sulfate hexahydrate (NiSO 4 6H 2 O) and 1.54575 g of boric acid (H 3 BO 3 ) was added into 500 mL of deionized water and stirred to prepare an electrolyte with a concentration of 0.05 mol / L.

[0076] When the concentration of the nickel source in the electrolyte is too low, it is easy to cause a lower deposition amount and poor catalytic performance; when the concentration of the nickel source in the electrolyte is too high, it is easy to cause the deposited catalyst to aggregate, thereby reducing the active area and performance of the catalyst.

[0077] The electrode system used for deposition is a three-electrode system.

[0078] Among them, the counter electrode in the three-electrode system is a platinum electrode (such as a platinum sheet), the reference electrode is a saturated calomel electrode, and the remaining electrodes are the electrodes corresponding to the silicon substrate in this application.

[0079] It should be noted that the use and principle of the three-electrode system can refer to the corresponding existing technology and will not be elaborated here.

[0080] For reference, the insulating layer in the present application may be epoxy resin attached to the non-polished surface of the silicon substrate.

[0081] Before setting the insulating layer, the method also includes pre-processing the silicon substrate.

[0082] For reference, the pre-treatment includes: removing impurities on the surface of the silicon substrate.

[0083] In some specific implementations, the silicon substrate to be processed may be placed in acetone for ultrasonic cleaning for 20 minutes, then placed in ethanol for ultrasonic cleaning for 20 minutes, and then placed in deionized water for ultrasonic cleaning for 15 minutes, so as to remove impurities on the surface of the silicon wafer.

[0084] Furthermore, the silicon substrate from which impurities have been removed is prepared into an electrode.

[0085] In some specific implementations, an ohmic contact may be prepared on a non-polished surface of a silicon substrate using an indium gallium alloy, and a silver wire may be bonded to the indium gallium alloy using a silver paste to lead out the ohmic contact.

[0086] After that, a small amount of epoxy resin may be attached to the polished surface to protect it and prevent the wire from catalytically reacting with the nickel metal nanoparticles (catalyst).

[0087] Furthermore, the prepared electrode is etched.

[0088] For reference, the etching solution used for etching is a hydrofluoric acid solution, for example, which can be prepared by mixing hydrofluoric acid with a mass fraction of 48-51% and deionized water in a volume ratio of 50:1.

[0089] In some specific embodiments, the prepared silicon wafer (electrode) with ohmic contact and protective layer can be immersed in a hydrofluoric acid solution for 2-5 minutes (such as 3 minutes), then taken out, cleaned with deionized water, and blown dry with nitrogen.

[0090] After etching, the silicon substrate has an oxide layer with a thickness of 2-6 nm.

[0091] Controlling the thickness of the oxide layer within the above range is beneficial to ensuring good ohmic contact and carrier transport.

[0092] After depositing the nickel metal nanoparticles, the sample after the nickel metal nanoparticles are deposited is mixed with an iron-containing solution (for example, by immersion) to introduce iron elements into the catalyst to improve the catalytic performance.

[0093] The iron-containing solution may be illustratively a ferrous sulfate solution.

[0094] In addition, the present application also provides applications of the above-mentioned silicon-based photoelectrocatalytic material, such as photoelectrocatalytic water decomposition.

[0095] As mentioned above, the present application improves the saturated photocurrent of photoelectrocatalytic water splitting by adjusting the etching degree of silicon, electrolyte concentration and constant current of electrodeposition. When the electrodeposition conditions are 2 mA current and 2 s electrodeposition time (2 mA-2 s), the material has the best catalytic performance. 100 mW / cm2 in 1 mol / L sodium hydroxide solution and AM1.5G 2 Under the condition of one sun, the cathode and anode can achieve a maximum current of 60mA / cm 2 The saturation photocurrent density is 200 mW / cm 2 Achieved a maximum of 100mA / cm2 under two sun intensity conditions 2 The saturated photocurrent density is higher than that of silicon-based photocatalytic materials in the prior art. When the current size of the electrodeposition condition is 1mA or 4mA and the electrodeposition time is 2s, the catalytic performance of the material is 100mW / cm2 in 1mol / L sodium hydroxide solution and AM1.5G. 2 Under the condition of one sun's intensity, only 36mA / cm 2 , by adding 0.05 mol / L FeSO 4 7H 2 After immersion in O for 3 h, its catalytic performance was significantly improved to 52 mA / cm 2 .

[0096] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0097] Example 1

[0098] This embodiment provides a silicon-based photoelectrocatalytic material, which is prepared by the following method:

[0099] Step (1): The cut N-type silicon wafer (single-side polishing, (100) crystal orientation, resistance 3Ω·cm) was ultrasonically cleaned in acetone, ethanol and deionized water for 20 min, 20 min and 15 min respectively to remove impurities on the surface of the silicon wafer;

[0100] Step (2): using indium gallium alloy to prepare ohmic contact on the unpolished surface of the silicon wafer, and using silver paste to bond silver wire to the indium gallium alloy to lead out the ohmic contact, and then applying epoxy resin on the back side and polished surface of the silicon wafer;

[0101] Step (3): Place the silicon substrate in a prepared hydrofluoric acid solution (hydrofluoric acid with a mass fraction of 50% and deionized water with a volume ratio of 50:1) and etch for 3 minutes to control the thickness of the silicon oxide layer to 5 nm. Then take the silicon substrate out, wash it with deionized water and blow it dry with nitrogen.

[0102] Step (4): 6.57125 g of nickel sulfate hexahydrate (NiSO 4 6H 2 O) and 1.54575 g of boric acid (H 3 BO 3 ) was added into 500 mL of deionized water and stirred to prepare an electrolyte for electrodeposition (concentration of 0.05 mol / L);

[0103] Step (5): Place the electrode obtained in step (3) into the prepared electrolyte using an electrode clamp, and perform constant current electrodeposition under a three-electrode system using a platinum sheet as a counter electrode and a saturated calomel electrode as a reference electrode, applying a constant current of 2 mA for 2 seconds.

[0104] The obtained sample is referred to as 2mA-2s sample.

[0105] Example 2

[0106] The difference between this embodiment and embodiment 1 is that:

[0107] The resistance of the silicon wafer is 1Ω·cm.

[0108] The current of constant current electrodeposition was 1 mA and the deposition time was 2 s.

[0109] The nickel source in the electrolyte is nickel chloride, and its concentration in the electrolyte is 0.04 mol / L.

[0110] The thickness of the oxide layer of the silicon wafer after etching is 2 nm.

[0111] Example 3

[0112] The difference between this embodiment and embodiment 1 is that:

[0113] The resistance of the silicon wafer is 5Ω·cm.

[0114] The current of constant current electrodeposition was 4 mA and the deposition time was 2 s.

[0115] The nickel source in the electrolyte is nickel nitrate, and its concentration in the electrolyte is 0.06 mol / L.

[0116] The thickness of the oxide layer of the silicon wafer after etching is 6 nm.

[0117] Example 4

[0118] The difference between this embodiment and embodiment 1 is that the silicon wafer is of P type.

[0119] Example 5

[0120] The difference between this embodiment and embodiment 1 is that after step (5), the deposited product is placed in 0.05 mol / L FeSO 4 7H 2 O for 3 h.

[0121] Comparative Example

[0122] The difference between this comparative example and Example 1 is:

[0123] The current of constant current electrodeposition was 10 mA and the deposition time was 2 s.

[0124] Test Example 1

[0125] ①, 100mW / cm provided by xenon lamp 2 Under illumination, the oxygen evolution performance of the sample provided in Example 1 (referred to as 2mA-2s sample, where 2mA refers to the deposition current and 2s refers to the deposition time) in 1M (i.e. mol / L, the same below) NaOH solution was tested using an electrochemical workstation at a test speed of 0.01V per second. The curve of current versus voltage is shown in FIG. Figure 1 shown.

[0126] The power density is 100mW / cm2 with a switching time of 5s. 2 The xenon light source was used, and the electrochemical workstation was used to test the oxygen evolution performance of the 2mA-2s sample in 1M NaOH solution in response to light. The test speed was 0.01V per second. The curve of current versus voltage is shown in Figure 2 shown.

[0127] Depend on Figure 1 and Figure 2 It can be seen that the oxygen evolution performance of the 2mA-2s sample is mainly contributed by light.

[0128] ②, 100mW / cm provided by xenon lamp 2 Under the illumination of , the oxygen evolution performance of samples prepared under different conditions in 1M NaOH solution was tested using an electrochemical workstation at a test speed of 0.01V per second. The curve of current versus voltage is shown in Figure 3 shown.

[0129] The difference between the above-mentioned samples is that the constant current used for electrodeposition is different, namely 1 mA, 2 mA, 4 mA and 10 mA, and the other conditions are the same.

[0130] Depend on Figure 3 It can be seen that the samples prepared under different electrodeposition conditions have different photocurrent density curves under the same test conditions, and the saturated photocurrent density has a large difference. When the current is 1-5mA, the saturated photocurrent density exceeds 40mA / cm 2 , where the sample under 2mA-2s electrodeposition condition was 100mW / cm under AM1.5G 2 It has the largest saturation photocurrent density (up to 60mA / cm 2 As a comparison (i.e. the comparative example above), when the current is 10 mA, the saturated optical density is only 27 mA / cm 2 .

[0131] ③, 100mW / cm provided by xenon lamp 2 and 200mW / cm 2 Under the illumination of , the oxygen evolution performance of the 2mA-2s sample in 1M NaOH solution was tested using an electrochemical workstation at a test speed of 0.01V per second. The curve of current versus voltage is shown in Figure 4 shown.

[0132] Depend on Figure 4 It can be seen that when the light density reaches 200mW / cm 2 The saturated photocurrent density can reach 100mA / cm 2 , which is higher than the silicon-based photoelectrocatalytic materials in the prior art (80mA / cm 2 ).

[0133] ④, 100mW / cm provided by xenon lamp 2 Under the illumination of 4 7H 2The oxygen evolution performance of O solution in 1M NaOH solution was tested before and after 3h, and the test speed was 0.01V per second. The curves of current vs. voltage are shown in Figure 5 and Figure 6 shown.

[0134] Depend on Figure 5 and Figure 6 It can be seen that for the samples under 1 mA-2 s and 4 mA-2 s electrodeposition conditions, the 4 7H 2 The saturated photocurrent density increased significantly after immersion in O for 3 h.

[0135] ⑤, 100mW / cm provided by xenon lamp 2 Under the illumination of , the hydrogen evolution performance of the 2mA-2s sample in 1M NaOH solution was tested using an electrochemical workstation at a test speed of 0.01V per second. The curve of current versus voltage is shown in Figure 7 shown.

[0136] Depend on Figure 7 It can be seen that the photoresponse current for HER is 100mW / cm under AM1.5G 2 The maximum saturation photocurrent density is nearly 60mA / cm 2 .

[0137] ⑥, 100mW / cm provided by xenon lamp 2 Under illumination, the 2mA-2s sample was tested in 0.65M NaOH, 0.35M LiOH and 2M HBO using an electrochemical workstation. 3 The stability of oxygen evolution performance in the mixed solution was tested under constant voltage, and the bias voltage used was 1.324V vs RHE. The curve of current changing with test time is shown in Figure 8 shown.

[0138] Depend on Figure 8 It can be seen that the sample under 2mA-2s electrodeposition condition has a current of 14mA / cm 2 At a constant photocurrent density of 0.65 M NaOH, 0.35 M LiOH and 2 M HBO 3 It continued to work in the mixed solution for 28 hours without a significant decrease in the photocurrent density.

[0139] Test Example 2

[0140] Taking Example 1 and Example 5 as examples, the obtained 2mA-2s sample without immersion treatment (corresponding to Example 1) and the 2mA-2s sample after immersion treatment (corresponding to Example 5) were subjected to SEM detection, and the results were as follows: Fig. 9 and Fig.10 shown.

[0141] Depend on Fig. 9 and Fig.10 It can be seen that the immersion treatment does not have a significant effect on the morphology of nickel metal nanoparticles, and the deposited nickel metal still appears as nanoparticles.

[0142] In summary, the silicon-based photoelectrocatalytic material provided in the present application has high catalytic performance and high saturated photocurrent of photoelectrocatalytic water decomposition. Its preparation method is simple and easy to operate. When it is used for photoelectrocatalytic water decomposition, it shows high saturated photocurrent of photoelectrocatalytic water decomposition.

[0143] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a silicon-based photoelectrocatalytic material, characterized in that: The method comprises the following steps: providing an insulating layer on the surface of the non-polished surface of the silicon substrate, and depositing nickel metal nanoparticles on the surface of the polished surface of the silicon substrate; The resistance of the silicon substrate is 1-5Ω·cm; Depositing nickel metal nanoparticles on the polished surface of the silicon substrate by constant current electrodeposition; the deposition current is 1-5 mA, and the deposition time is 1-5 s; The electrolyte used for deposition includes a nickel source, and the electrode system used for deposition is a three-electrode system; the concentration of the nickel source contained in the electrolyte is 0.04-0.06 mol / L.

2. The preparation method according to claim 1, characterized in that: The silicon substrate has a (100) crystal orientation; the silicon substrate is an N-type silicon wafer or a P-type silicon wafer.

3. The preparation method according to claim 1, characterized in that: The particle size of the nickel metal nanoparticles is 20-40 nm.

4. The preparation method according to claim 1, characterized in that: After an insulating layer is arranged on the surface of the non-polished surface of the silicon substrate, nickel metal nanoparticles are deposited on the surface of the polished surface of the silicon substrate.

5. The preparation method according to claim 1, characterized in that: The nickel source includes at least one of nickel sulfate hexahydrate, nickel chloride and nickel nitrate.

6. The preparation method according to claim 1, characterized in that: The electrolyte solution also includes a pH adjuster.

7. The preparation method according to claim 6, characterized in that: The pH adjuster includes boric acid.

8. The preparation method according to claim 1, characterized in that: The counter electrode in the three-electrode system is a platinum electrode, and / or the reference electrode in the three-electrode system is a saturated calomel electrode.

9. The preparation method according to claim 1, characterized in that: The insulating layer is formed by attaching epoxy resin to the non-polished surface of the silicon substrate.

10. The preparation method according to claim 9, characterized in that: Before providing the insulating layer, the method further includes pre-processing the silicon substrate.

11. The preparation method according to claim 10, characterized in that: The pre-treatment includes removing impurities on the surface of the silicon substrate.

12. The preparation method according to claim 11, characterized in that: The pre-treatment also includes preparing the silicon substrate into an electrode after removing impurities.

13. The preparation method according to claim 12, characterized in that: The pre-treatment also includes etching the prepared electrode.

14. The preparation method according to claim 13, characterized in that: The etching solution used for etching is a hydrofluoric acid solution; and / or, after etching, the thickness of the oxide layer of the silicon substrate is 2-6 nm.

15. The preparation method according to claim 1, characterized in that: The method also includes mixing the sample after the nickel metal nanoparticles are deposited with an iron-containing solution.

16. The preparation method according to claim 15, characterized in that: The iron-containing solution is a ferrous sulfate solution.

17. Use of the silicon-based photoelectrocatalytic material prepared by the preparation method according to any one of claims 1 to 16, wherein the silicon-based photoelectrocatalytic material is used for photoelectrocatalytic water decomposition.

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