Method for photoelectrolysis of water by non-metallic element doped fullerene composite bismuth vanadate

Abstract

The application belongs to the technical field of photoelectrolysis water material preparation, and relates to a method for preparing a non-metal element doped fullerene composite bismuth vanadate photoelectrolysis water, which comprises the following steps: s1, cleaning a conductive substrate; s2, performing non-metal element doping treatment on fullerene powder through a chemical vapor deposition method; s3, stirring modified fullerene after s2 treatment, a Bi source and a V source to prepare a catalyst slurry; s4, placing the conductive surface of the conductive substrate downward in the catalyst slurry, and performing hydrothermal in-situ growth to prepare a photoelectrocatalysis film; and s5, after natural cooling to room temperature, taking out the conductive substrate, and then heating and calcining to obtain a photoelectrolysis water electrode. The method is characterized in that the fullerene is doped with different metal elements through the chemical vapor deposition method, and then a uniform, dense and firm catalyst film is formed on the FTO through the hydrothermal in-situ growth method, and then a more stable and high-activity photoelectrolysis water electrode is obtained. The preparation method is simple, low in cost, and can realize large-scale electrode preparation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photoelectrolysis of water material, and relates to a method for photoelectrolysis of water of non-metallic element doped fullerene composite bismuth vanadate. BACKGROUND

[0002] With the intensification of energy crisis and environmental problems, the realization of efficient and stable photoelectrolysis of water has important practical significance. Photoelectrolysis of water technology is a water decomposition process driven by light energy, which realizes the decomposition of water molecules to generate hydrogen, oxygen, hydrogen peroxide and other valuable products by converting solar energy or other light sources into chemical energy. This process relies on the light absorption, electron conduction and catalytic activity of the photoelectrode material, and has both energy conversion and environmental benefits, and is considered as one of the important ways to realize sustainable energy system. As an important research direction of solar energy conversion technology, photoelectrolysis of water has received extensive attention in recent years. Traditional electrolysis of water technology consumes a large amount of electricity, while photoelectrolysis of water technology utilizes solar energy through photovoltaic effect, thereby reducing the demand for external power and greatly improving energy utilization efficiency.

[0003] Among many materials, bismuth vanadate (BiVO4) is widely used in photoelectrocatalysis due to its suitable band gap and good light excitation performance. Due to the slow oxidation-reduction reaction (ORR) and water oxidation reaction (WOR) kinetics, poor conductivity and high electron-hole pair recombination rate, most of the reported BiVO4 photoanodes are far below the theoretical expected photocurrent level. Therefore, in the field of photoelectrocatalysis, researchers have devoted to developing various strategies to improve the photoelectrocatalytic activity of BiVO4. Through morphology control, doping, composite heterojunction formation and other ways, the carrier mobility and conductivity are improved, and the purpose of improving the photoelectrocatalytic activity is finally achieved.

[0004] Recently, the modification method of using carbon-based materials to composite with semiconductor metal oxides has attracted widespread attention. Specifically, carbon-based materials have high specific surface area, special electronic properties, binding effect and strong physical and chemical stability, which are beneficial to further promote photoelectrocatalysis. Although it has been recognized that carbon-based materials play a key role as composite catalyst materials in the fields of photocatalysis, electrocatalysis and photoelectrocatalysis, C 60 As an important part of carbon-based materials, people rarely use its electronic structure and properties to further modify to improve the photoelectrocatalytic activity. 60 C is a carbon-based material with unique electronic properties, and due to its relatively low LUMO (lowest unoccupied molecular orbital) energy, it can be used as an excellent electron acceptor in catalytic reactions. However, C 60The high-symmetry cage structure makes it have high stability, and cannot provide rich catalytic active sites in the reaction. By utilizing the defects of other non-metallic elements B, N, P, S doped C 60 After being compounded with BiVO4, the photoelectron transmission capacity of the catalyst material can be maximally improved.

[0005] The application CN112058275B discloses a thin film electrode alkaline water photocatalyst and a preparation method and application thereof. Pt and Ni are deposited on the surface of the thin film electrode in sequence, and then PtNi / Ni(OH)2 is prepared on the surface of the thin film electrode through calcination and in-situ electrochemical oxidation, so that the target catalyst with the PtNi alloy nanolayer attached to the surface of the thin film electrode and the amorphous Ni(OH)2 attached to the surface of the PtNi alloy nanolayer is obtained.

[0006] The application CN109706478B discloses a hydrogen-reduced thin-layer titanium carbide loaded cuprous oxide photocathode material for water photoelectrolysis and a preparation method thereof. The cuprous oxide is prepared on the basis of conductive glass or copper, and the hydrogen-reduced thin-layer titanium carbide is loaded on the surface of the cuprous oxide, so that the composite photoelectrode material hydrogen-reduced thin-layer titanium carbide loaded cuprous oxide with high photoelectrochemical performance is synthesized.

[0007] The application CN111569896A discloses a BiVO4-Ni / Co3O4 heterojunction forming method. First, BiOI nanoparticles are grown on an FTO substrate by electrodeposition, then vanadyl acetylacetonate aqueous solution is added to the surface of the FTO, and bismuth vanadate (BiVO4) is generated after high-temperature calcination. Through continuous ion adsorption reaction, the FTO is placed in a deionized water solution containing Co(NO3)2·6H2O, Ni(NO3)2·6H2O, C6H 12 N4, CH4N2O and NH4F, and after hydrothermal reaction, the catalyst is obtained by washing with deionized water, annealing and natural cooling to room temperature.

[0008] The application CN109706478A discloses a hydrogen-reduced thin-layer titanium carbide loaded cuprous oxide photocathode material for water photoelectrolysis and a preparation method thereof. The cuprous oxide is prepared on the basis of conductive glass or copper, and the hydrogen-reduced thin-layer titanium carbide is loaded on the surface of the cuprous oxide, so that the composite photoelectrode material hydrogen-reduced thin-layer titanium carbide loaded cuprous oxide with high photoelectrochemical performance is synthesized. x .

[0009] The application CN105088265B discloses a cuprous oxide composite titanium dioxide nanowire array photoanode material for photoelectrolysis of water and a preparation method thereof. First, a titanium dioxide nanowire array is synthesized by a hydrothermal method, and then the titanium dioxide nanowire array is further heat-treated to form an anatase crystalline. Then, cuprous oxide is grown on the titanium dioxide nanowire array by a hydrothermal reaction in the presence of a polyamine polymer.

[0010] The above-mentioned application method sequentially deposits a plurality of metal nanolayers on the surface of a thin film electrode, and then forms a catalyst layer on the surface of the electrode by calcination and in-situ electrochemical oxidation. Alternatively, a cuprous oxide photo-cathode material is prepared on a conductive glass or copper substrate, and a thin layer of titanium carbide reduced by hydrogen is loaded on the surface of the cuprous oxide photo-cathode material to form a composite photo-electrode material with high photo-electrochemical performance. Alternatively, BiOI nanoparticles are grown on a substrate by electrodeposition, and then a BiVO4-Ni / Co3O4 heterojunction catalyst is prepared by high-temperature calcination and continuous ion adsorption reaction. Alternatively, a titanium dioxide nanowire array is prepared by a hydrothermal method, and then cuprous oxide is grown on the surface of the titanium dioxide nanowire array to form a composite photo-anode material for photoelectrolysis of water.

[0011] However, these catalytic electrodes in the prior art all need a large number of pre-operations and complex process flows during preparation, and precise instruments and high-cost raw materials are required in the process, and the operation method of the operator has a high requirement. In addition, more stable and better conductive carbon-based materials are not involved in most experiments.

[0012] Therefore, it is crucial for the industrial application of photoelectrolysis of water to seek a carbon-based catalyst preparation method for compounding a catalyst with BiVO4, which has low cost, simple process, and good electrochemical stability and catalytic performance. SUMMARY

[0013] The technical solution adopted by the application to solve the technical problem is a method for photoelectrolysis of water of a non-metal element doped fullerene composite bismuth vanadate, comprising the following steps:

[0014] Step s1, cleaning the conductive substrate to remove impurities on the surface of the conductive substrate;

[0015] Step s2, performing non-metal element doping treatment on the fullerene powder by a chemical vapor deposition method to generate modified fullerene;

[0016] Step s3, dissolving the modified fullerene treated in step s2 in a solvent A; dissolving a Bi source and a V source in a solvent B, and stirring to prepare a catalyst slurry;

[0017] Step s4, after mixing the catalyst slurry prepared in step s3, the mixture is transferred into a chemical reaction device, and the conductive surface of the conductive substrate cleaned in step s1 is placed in the chemical reaction device with the conductive surface facing downward, and the conductive substrate is subjected to hydrothermal in-situ growth to prepare a photoelectrocatalytic film;

[0018] Step s5, after the reaction in step s4 is completed, the conductive substrate is taken out and placed in a high-temperature heating device for heating and calcination to obtain a photoelectrolysis electrode.

[0019] In step s2, the non-metallic elements include one or more of nitrogen, phosphorus, sulfur, boron, fluorine, and chlorine.

[0020] In step s3, the solvent A includes one or more of toluene, benzene, carbon tetrachloride, and cumene; and the solvent B includes one or more of ethylene glycol, ethanol, methanol, isopropanol, and deionized water.

[0021] Preferably, in step s3, the Bi source includes one or more of bismuth nitrate pentahydrate, bismuth subcarbonate dihydrate, and bismuth sulfate; and the V source includes one or more of ammonium metavanadate, vanadium pentoxide, and vanadium acetylacetonate.

[0022] Preferably, in step s1, the conductive substrate includes fluorine-doped silicon dioxide conductive glass FTO, indium tin oxide transparent conductive film glass ITO, and stainless steel plate; and in step s2, the fullerene is C 60 .

[0023] Preferably, in step s4, the chemical reaction device includes a reaction kettle, a high-pressure kettle, a stirring reactor, a continuous flow reactor, a microreactor, a batch reactor, a fixed bed reactor, and a fluidized bed reactor; and in step s5, the high-temperature heating device includes a muffle furnace, a tube furnace, a box furnace, a vacuum furnace, an atmosphere furnace, an electric resistance furnace, and an induction furnace.

[0024] Preferably, in step s1, the cleaning step is to sequentially use deionized water, acetone, isopropanol, and ethanol to ultrasonically clean the conductive substrate for 5-20 minutes.

[0025] Preferably, in step s2, the fullerene and the non-metallic elements are thoroughly mixed, then placed in a tube furnace, vacuumed for 2-5 times, and then calcined at 300-1000°C for 1-4 hours under N2 atmosphere.

[0026] Preferably, in step s4, the hydrothermal time is 6-18 hours, and the hydrothermal temperature is 120-200°C.

[0027] Preferably, in step s5, the temperature of the high-temperature heating device is set to 350-500°C, the heating rate is 5-10°C / min, and the calcination time is 1-4 hours.

[0028] Preferably, the size of the conductive substrate comprises: 1cm*1cm, 1cm*2cm, 2cm*2cm, 2cm*3cm.

[0029] The beneficial effects of the present application are:

[0030] The present application dopes fullerenes by chemical vapor deposition method, combines with hydrothermal in-situ growth method to make the catalyst powder uniformly distributed on the surface of FTO substrate, forms a firm and uniform catalyst layer, and the catalyst does not obviously fall off after multiple photoelectrochemical tests and has good light transmittance. In addition, the present application uses non-metallic element doped fullerenes as composite materials and FTO as electrode raw materials, which has the advantages of low price, rich yield, easy to obtain, and low requirement for equipment in the preparation process, easy to operate and simple preparation method, and can realize industrialized large-scale electrode preparation. Therefore, the photoelectrolysis catalyst prepared by the present application can effectively improve the photocurrent of the original BiVO4 itself, has excellent stability, and the preparation method is simple and easy to control, thereby effectively reducing the cost of photoelectrolysis of water and promoting the popularization and application of this technology. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is an electrode sample scanning electron microscope morphology diagram of embodiment 1 of the method for preparing non-metallic element doped fullerenes composite bismuth vanadate photoelectrolysis of water of the present application;

[0032] Figure 2 is a scanning electron microscope morphology diagram of the catalyst sample of embodiment 2 of the present application;

[0033] Figure 3 is an XRD diagram of the catalyst sample of embodiment 2 of the present application;

[0034] Figure 4 is an XPS diagram of the catalyst sample of embodiment 2 of the present application;

[0035] Figure 5 is a linear sweep voltammetry test diagram of different non-metallic element doped catalyst photoanode examples of the present application. DETAILED DESCRIPTION

[0036] The related technologies in the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0037] The present application aims to provide a method for photoelectrolysis of water by non-metallic element doped fullerene composite bismuth vanadate, which has low requirements for equipment, simple process and low cost in the process of electrolysis of water, further expands the selection range of photoelectrolysis composite catalyst, reduces the preparation cost of catalyst, and improves the efficiency of photoelectrolysis of water.

[0038] Referring to Figures 1 to 5 The present application provides a method for photoelectrolysis of water by non-metallic element doped fullerene composite bismuth vanadate, which specifically comprises the following steps:

[0039] s1: cleaning fluorine-doped silicon dioxide conductive glass (FTO) to remove impurities on the surface of FTO;

[0040] s2: non-metallic element doping treatment of fullerene (C 60 ) powder by chemical vapor deposition (CVD);

[0041] s3: dissolving the modified fullerene treated in s2 in toluene, dissolving Bi source and V source in ethylene glycol and deionized water, and stirring to prepare catalyst slurry;

[0042] s4: mixing the catalyst slurry prepared in s3 and transferring it into the reaction kettle of the polytetrafluoroethylene inner liner, and placing the FTO conductive surface treated in s1 in the reaction kettle of the polytetrafluoroethylene inner liner, and hydrothermal in-situ growth to prepare a photoelectrocatalytic film;

[0043] s5: after the reaction is completed, the reaction kettle is naturally cooled to room temperature, and the FTO is taken out and heated and calcined in a muffle furnace to obtain a photoelectrolysis electrode.

[0044] Further, in the step s1, the catalyst substrate uses FTO with good light transmittance and conductivity, and the size is 2cm*3cm.

[0045] Further, in the step s1, the cleaning step is to sequentially use deionized water, acetone, isopropyl alcohol and ethanol for ultrasonic bath of FTO for 10min respectively.

[0046] Further, in the step s2, the non-metallic element is nitrogen, phosphorus, sulfur and boron, and urea, sodium hypophosphite monohydrate, sublimed sulfur and sodium borohydride are used as nitrogen source, phosphorus source, sulfur source and boron source respectively.

[0047] Further, in the step s2, after the fullerene is fully mixed with the nitrogen source, it is placed in a tube furnace and vacuumed for 3 times, and then calcined at 1000℃ under N2 atmosphere for 2h. The doping processes of phosphorus source, sulfur source and boron source are similar to that of nitrogen source, and only need to set the calcination temperature to 800℃, 800℃ and 400℃ respectively.

[0048] Further, in the step s3, the solvent for the treated fullerene is toluene (1 mg / 5 mL).

[0049] Further, in the step s3, the Bi source is bismuth nitrate pentahydrate (Bi(NO3)3·5H2O), the V source is ammonium metavanadate (NH4VO3), and the solvent is ethylene glycol and deionized water, wherein the ratio of Bi to V is 1:1.

[0050] Further, in the step s4, the hydrothermal time is 12 h, and the hydrothermal temperature is 180℃.

[0051] Further, in the step s5, the temperature of the muffle furnace is set to 400℃, the heating rate is 5℃ / min, and the calcination time is 2 h.

[0052] Embodiment

[0053] The embodiment provides a method for photoelectrolysis of water by non-metal element doped fullerene composite bismuth vanadate, comprising the following steps:

[0054] s1: cleaning fluorine-doped silicon dioxide conductive glass (FTO) to remove impurities on the surface of the FTO;

[0055] s2: performing non-metal element doping treatment on fullerene (C60) powder by a chemical vapor deposition method (CVD);

[0056] s3: preparing catalyst slurry by stirring modified fullerene after the treatment in s2, a Bi source, a V source and a solvent;

[0057] s4: transferring the catalyst slurry prepared in s3 into a reaction kettle with a polytetrafluoroethylene liner, and placing the FTO conductive surface after the cleaning treatment in s1 in the reaction kettle with the polytetrafluoroethylene liner as well, and then performing in-situ hydrothermal growth to prepare a photoelectrocatalytic film;

[0058] s5: after the reaction is completed, naturally cooling the reaction kettle to room temperature, and taking out the FTO to perform heating calcination in a muffle furnace to obtain a photoelectrolysis electrode.

[0059] The following specific embodiments are given to further illustrate the present application:

[0060] Embodiment 1:

[0061] 1) Cleaning of FTO

[0062] Deionized water, acetone, isopropyl alcohol and ethanol are used to sequentially ultrasonic bath the FTO for 10 min, respectively, to remove impurities on the surface of the FTO, so that the film can uniformly cover the entire FTO surface during in-situ hydrothermal growth.

[0063] 2) In-situ hydrothermal growth to prepare a catalytic film

[0064] A composite catalyst thin film was grown on a conductive fluorine-doped tin oxide (FTO) coated glass substrate by a hydrothermal in-situ growth method. 0.485 g of Bi(N03)3.5H20 and 0.117 g of NH4V03 were weighed using a balance and dissolved in a mixed solvent of 20 mL of ethylene glycol and 10 mL of deionized water; Bi(N03)3.5H20 and NH4V03 were mixed thoroughly by magnetic stirring for 30 min; the mixed solution and 5 mL of a toluene solution were transferred to a Teflon-lined stainless steel reaction kettle, a pre-cleaned FTO glass substrate was placed against the Teflon-lined wall with its conductive side facing down, the hydrothermal time was 12 h, and the hydrothermal temperature was 180 °C; after the reaction was completed, the reaction kettle was naturally cooled to room temperature.

[0065] 3) Heat calcination

[0066] The FTO in the reaction kettle was taken out and the surface of the FTO was rinsed with deionized water, and after drying at room temperature, it was annealed in a muffle furnace at a heating rate of 5 °C / min at 400 °C for 2 h to obtain a photoelectrolysis water electrode.

[0067] Example 2:

[0068] 1) Cleaning of FTO

[0069] Deionized water, acetone, isopropanol, and ethanol were used in sequence to ultrasonically clean the FTO for 10 min to remove impurities on the surface of the FTO, so that the thin film could uniformly cover the entire FTO surface during hydrothermal in-situ growth.

[0070] 2) Hydrothermal in-situ growth to prepare a catalyst thin film

[0071] A composite catalyst thin film was grown on a conductive fluorine-doped tin oxide (FTO) coated glass substrate by a hydrothermal in-situ growth method. 0.485 g of Bi(N03)3.5H20 and 0.117 g of NH4V03 were weighed using a balance and dissolved in a mixed solvent of 20 mL of ethylene glycol and 10 mL of deionized water; Bi(N03)3.5H20 and NH4V03 were mixed thoroughly by magnetic stirring for 30 min; the mixed solution and 5 mL of a toluene solution were transferred to a Teflon-lined stainless steel reaction kettle, a pre-cleaned FTO glass substrate was placed against the Teflon-lined wall with its conductive side facing down, the hydrothermal time was 12 h, and the hydrothermal temperature was 180 °C; after the reaction was completed, the reaction kettle was naturally cooled to room temperature. 60 A composite catalyst thin film was grown on a conductive fluorine-doped tin oxide (FTO) coated glass substrate by a hydrothermal in-situ growth method. 0.485 g of Bi(N03)3.5H20 and 0.117 g of NH4V03 were weighed using a balance and dissolved in a mixed solvent of 20 mL of ethylene glycol and 10 mL of deionized water; Bi(N03)3.5H20 and NH4V03 were mixed thoroughly by magnetic stirring for 30 min; the mixed solution and 5 mL of a toluene solution were transferred to a Teflon-lined stainless steel reaction kettle, a pre-cleaned FTO glass substrate was placed against the Teflon-lined wall with its conductive side facing down, the hydrothermal time was 12 h, and the hydrothermal temperature was 180 °C; after the reaction was completed, the reaction kettle was naturally cooled to room temperature.

[0072] 3) Heat calcination

[0073] The FTO was removed from the reactor and its surface was rinsed with deionized water. After drying at room temperature, it was annealed in a muffle furnace at 400°C for 2 hours at a heating rate of 5°C / min to obtain the photoelectrochemical water splitting electrode.

[0074] Example 3:

[0075] 1) Cleaning of FTO

[0076] Deionized water, acetone, isopropanol and ethanol were used to ultrasonically bathe FTO for 10 minutes in sequence to remove impurities on the FTO surface, so that the film could uniformly cover the entire FTO surface during hydrothermal in-situ growth.

[0077] 2) Chemical vapor deposition (CVD) for C 60 Powder is doped with boron

[0078] Measure 20mg C using a weighing balance. 60 The powder was placed in a porcelain boat for later use; 10 mg of NaBH4 was measured as the B source; after thorough mixing, it was placed in a tube furnace, and after checking the airtightness, the furnace was evacuated three times to ensure that there was no oxygen in the tube furnace; it was calcined at 400°C for 2 hours under N2 atmosphere; the powder was thoroughly washed with deionized water and dried at 80°C in a forced-air drying oven, and then collected for later use.

[0079] 3) Preparation of catalytic thin films by hydrothermal in-situ growth

[0080] A composite catalyst film was grown on a conductive fluorine-doped tin oxide (FTO) coated glass substrate using a hydrothermal in-situ growth method. 0.485 g of Bi(NO3)3·5H2O and 0.117 g of NH4VO3 were weighed using a weighing balance and dissolved in a mixed solvent of 20 mL ethylene glycol and 10 mL deionized water. The mixture was magnetically stirred for 30 min to ensure thorough mixing of Bi(NO3)3·5H2O and NH4VO3. 1 mg of the doped BC... 60 The powder was dissolved in 5 mL of toluene solution and sonicated until completely dissolved. The two mixed solutions were then transferred to a stainless steel reactor lined with Teflon. A pre-cleaned FTO glass substrate was placed against the wall of the Teflon liner with its conductive side facing down. The hydrothermal time was 12 h and the hydrothermal temperature was 180 °C. After the reaction was completed, the reactor was allowed to cool naturally to room temperature.

[0081] 4) Heating and calcining

[0082] The FTO was removed from the reactor and its surface was rinsed with deionized water. After drying at room temperature, it was annealed in a muffle furnace at 400°C for 2 hours at a heating rate of 5°C / min to obtain the photoelectrochemical water splitting electrode.

[0083] Example 4:

[0084] 1) Cleaning of FTO

[0085] The FTO was ultrasonically bathed in deionized water, acetone, isopropanol, and ethanol in sequence for 10 min each to remove impurities on the surface of the FTO, so that the thin film can uniformly cover the entire FTO surface during in-situ growth by hydrothermal method.

[0086] 2) N-doping of C 60 powder

[0087] 20 mg of C 60 powder was weighed using a balance and placed in a porcelain boat; 500 mg of urea was weighed as the N source; after thorough mixing, the mixture was placed in a tube furnace, checked for airtightness, and vacuumed three times to ensure that there was no oxygen in the tube furnace; under N2 atmosphere, calcination was performed at 1000°C for 2 h; the treated powder was washed thoroughly with deionized water and dried in a forced air drying oven at a temperature of 80°C; after collection, it was ready for use.

[0088] 3) Preparation of catalytic thin film by in-situ growth by hydrothermal method

[0089] A composite catalyst thin film was grown on a conductive fluorine-doped tin oxide (FTO) coated glass substrate by in-situ growth by hydrothermal method. 0.485 g of Bi(NO3)3·5H2O and 0.117 g of NH4VO3 were dissolved in 20 mL of ethylene glycol and 10 mL of deionized water; the mixture was stirred magnetically for 30 min to ensure that the Bi(NO3)3·5H2O and NH4VO3 were thoroughly mixed; 1 mg of N-C 60 powder treated with N-doping was dissolved in 5 mL of toluene solution and ultrasonically dissolved; the two mixed solutions were transferred to a Teflon-lined stainless steel reactor, and the pre-cleaned FTO glass substrate was placed against the Teflon-lined wall with the conductive side facing down; the hydrothermal time was 12 h and the hydrothermal temperature was 180°C; after the reaction was completed, the reactor was allowed to cool to room temperature naturally.

[0090] 4) Calcination by heating

[0091] The FTO in the reactor was removed and the surface of the FTO was rinsed with deionized water; after drying at room temperature, the FTO was annealed in a muffle furnace at a heating rate of 5°C / min at 400°C for 2 h to obtain a photoelectrolysis water electrode.

[0092] Example 5:

[0093] 1) Cleaning of FTO

[0094] The FTO was ultrasonically bathed in deionized water, acetone, isopropanol, and ethanol in sequence for 10 min each to remove impurities on the surface of the FTO, so that the thin film can uniformly cover the entire FTO surface during in-situ growth by hydrothermal method.

[0095] 2) C powder was doped with B by chemical vapor deposition (CVD) 60 B-doped powder

[0096] 20 mg of C powder was weighed using a balance 60 The powder was kept in a porcelain boat for later use; 500 mg of sodium hypophosphite monohydrate was weighed as the P source; after mixing well, it was put into a tube furnace, checked for airtightness, and vacuumed three times to ensure that there was no oxygen in the tube furnace; it was calcined at 800°C for 2 h under N2 atmosphere; the treated powder was washed with deionized water and dried in a forced air drying oven at 80°C; after collection, it was kept for later use.

[0097] 3) Preparation of catalytic thin film by hydrothermal in-situ growth

[0098] A composite catalyst thin film was grown on a conductive fluorine-doped tin oxide (FTO) coated glass substrate by hydrothermal in-situ growth. 0.485 g of Bi(NO3)3·5H2O and 0.117 g of NH4VO3 were dissolved in 20 mL of ethylene glycol and 10 mL of deionized water mixed solvent using a balance; Bi(NO3)3·5H2O and NH4VO3 were mixed well by magnetic stirring for 30 min; 1 mg of P-C 60 powder was dissolved in 5 mL of toluene solution and completely dissolved by ultrasonic; the two mixed solutions were transferred to a Teflon-lined stainless steel reactor, and the pre-cleaned FTO glass substrate was placed against the Teflon-lined wall with the conductive side facing down, the hydrothermal time was 12 h, and the hydrothermal temperature was 180°C; after the reaction was completed, the reactor was naturally cooled to room temperature.

[0099] 4) Calcination by heating

[0100] The FTO in the reactor was removed and the surface of the FTO was rinsed with deionized water, dried at room temperature, and then annealed at 400°C for 2 hours in a muffle furnace at a heating rate of 5°C / min to obtain a photoelectrolysis water electrode.

[0101] Example 6:

[0102] 1) Cleaning of FTO

[0103] Deionized water, acetone, isopropanol, and ethanol were used in sequence to ultrasonically clean the FTO for 10 min to remove impurities on the surface of the FTO, so that the thin film could uniformly cover the entire surface of the FTO during hydrothermal in-situ growth.

[0104] 2) S-doped C powder by chemical vapor deposition (CVD) 60

[0105] 20 mg of C powder was weighed using a balance 60 ​The powder was prepared in a porcelain boat; 100 mg of sublimed sulfur was weighed as the S source; after mixing thoroughly, it was placed in a tube furnace, and after checking the airtightness, it was vacuumed three times to ensure that there was no oxygen in the tube furnace; after calcination at 800°C for 2 h under a N2 atmosphere, the treated powder was washed with deionized water and dried in a forced air drying oven at 80°C; after collection, it was ready for use.

[0106] 3) Preparation of a catalytic film by hydrothermal in-situ growth

[0107] A composite catalyst film was grown on a conductive fluorine-doped tin oxide (FTO) coated glass substrate by hydrothermal in-situ growth. 0.485 g of Bi(NO3)3·5H2O and 0.117 g of NH4VO3 were weighed using a balance and dissolved in 20 mL of ethylene glycol and 10 mL of deionized water; the Bi(NO3)3·5H2O and NH4VO3 were mixed thoroughly by magnetic stirring for 30 min; 1 mg of the S-C 60 The powder was dissolved in 5 mL of toluene solution and ultrasonically dissolved completely; the two mixed solutions were transferred to a Teflon-lined stainless steel reactor, and the pre-cleaned FTO glass substrate was placed against the Teflon-lined wall with the conductive surface facing down, the hydrothermal time was 12 h, and the hydrothermal temperature was 180°C; after the reaction was completed, the reactor was naturally cooled to room temperature.

[0108] 4) Calcination by heating

[0109] The FTO in the reactor was removed and the surface of the FTO was rinsed with deionized water; after drying at room temperature, the FTO was annealed in a muffle furnace at a heating rate of 5°C / min at 400°C for 2 h to obtain a photoelectrolysis water electrode.

[0110] Figure 1 The scanning electron microscope (SEM) morphology of Example 1 of the present application and Example 3 of the present application is shown. By hydrothermal in-situ growth and calcination, an X-C60 / BiVO4 photoanode film was prepared on an FTO conductive glass substrate. Figure 1 It is clearly shown that a rice grain-like particle structure is formed during the preparation process, and the hydrothermal in-situ growth method enables the catalytic material to be more uniformly distributed on the FTO conductive glass substrate. Figure 2 The transmission electron microscope (TEM) morphology of Example 3 is shown, and the high-resolution transmission electron microscope (HR-TEM) clearly shows that the B-C 60 / BiVO4 crystal has a relatively smooth surface, and the image has a clear lattice spacing of 0.5105 nm, corresponding to the (1 1 2) plane of monoclinic BiVO4 (PDF #83-1699). However, the lattice structure of the B-C60 / BiVO4 sample remains consistent with that of BiVO4, and there is no change, and it is difficult to confirm the presence of C 60 from the HR-TEM image.

[0111] Figure 3 The X-ray diffraction (XRD) patterns of the samples from Example 1 and Example 3 of this invention are shown below for comparison. 60 With BC 60 The X-ray diffraction (XRD) pattern shows that after the B atom is incorporated, the C... 60 The diffraction peaks on the (1 1 1), (2 2 0), (3 1 1), and (22 2) crystal planes all shift towards a smaller 2θ, indicating that the cell expansion distortion occurs after doping, which confirms the successful doping of element B. Compared to commercial C... 60 The lattice spacing of the (2 2 0) plane of the molecule is 0.4918 nm because of the C atoms doped with B atoms. 60 The expansion and distortion of the molecular unit cell leads to an increase in the lattice spacing. However, compared to the original BiVO4 photoanode, BC... 60 No significant peak changes were observed in the combined X-ray diffraction (XRD) pattern, indicating that BC 60 The crystal structure of BiVO4 is not changed after being combined with it.

[0112] Figure 4 The XPS spectra of the samples from Example 1 and Example 3 of this invention are shown in BC. 60 Characteristic XPS peaks for Bi, V, and O were observed in the XPS spectra of both / BiVO4 and BiVO4; in addition, BC 60 / BiVO4 exhibits a B1s peak at a binding energy of 187 eV, indicating that BC 60 The presence of BC can be seen in the B1s spectrum. 60 In BiVO4, boron exists as oxides and in lower oxidation states. Compared to the BiVO4 sample, BC... 60 The Bi 4f peak of the / BiVO4 photoanode shifts towards the direction of higher binding energy, which is attributed to Bi (5+x)+ Speciation. Based on the above results, it can be considered that the partial substitution of C by B atoms... 60 The C site in C can alter the electron density around it. 60 The change in electronegativity, in turn, causes the Bi sites in BiVO4 to lose some electrons, thus disrupting the charge balance in BiVO4. This further effectively attracts photogenerated electrons from the BiVO4 surface, reducing electron-hole recombination in the semiconductor catalyst and improving the overall photoelectrocatalytic performance of the composite catalyst. Therefore, in C 60 Adding B to the mixture can effectively improve BC. 60 Activity and stability of the photoanode of the / BiVO4 composite catalyst.

[0113] Figure 5 For photoelectrochemical tests of different non-metallic element doped samples of all embodiments of the present application, a xenon lamp (100 mW cm -2 ) was used to simulate the standard spectrum of the earth's surface (AM 1.5G), and the photoelectrochemical performance of B-C 60 / BiVO4 catalyst photoanodes was measured in 0.5 M Na2SO4 electrolyte. For comparison, the original BiVO4, untreated C 60 composite with BiVO4 and C 60 doped with various non-metallic elements X (X is a non-metallic element N, P and S) and C -2 composite with BiVO4 were also studied. As shown in the figure, the photocurrent density of the original BiVO4 photoanode was relatively low (only 0.035 mA cm 60 ), while the untreated C 60 / BiVO4 also did not significantly improve the photocurrent density of the photoanode, because the reaction kinetics at the anode and electrolyte interface was slow, and a large number of electron-hole pairs did not participate in the surface redox reaction; at the same time, the onset potential of C 60 / BiVO4 increased, because the unmodified C 60 was in a relatively stable spherical structure, and the stable C atoms on the surface could not act as catalytically active sites in photoelectrocatalysis, and even the attachment of C 60 could cause the original BiVO4 active sites to be unable to be exposed, which caused the onset potential of the photoelectrocatalytic reaction to increase. Obviously, after non-metallic element doping treatment of C 60 , the photoelectric performance of the composite catalyst material changed greatly, as shown in the figure, in which N-C 60 / BiVO4, S-C 60 / BiVO4 and B-C 60 / BiVO4 catalyst photoanodes had a large increase in photocurrent density, and the photoelectrocatalytic water oxidation activity was greatly improved, and the B-C -2 / BiVO4 photoanode could reach 0.29 mA cm 60 at 1.59 V vs. RHE, which was 7 times that of the original BiVO4 material. The electrochemical impedance spectra of each sample under dark and light conditions are also shown in the figure, and the impedance of the untreated C 60 composite with BiVO4 was much larger than that of other samples, because the simple C 60 attachment of BiVO4 formed a heterojunction interface that inhibited the transmission of electrons, while after non-metallic element doping, the X-C 60The upper electronic arrangement changes, and the electronegativity of the surrounding C atoms is also changed, which affects the transmission of electrons between X-C 60 and BiVO4. P-C 60 / BiVO4, S-C 60 / BiVO4, B-C 60 The N-C 60 / BiVO4 resistance value is slightly lower than that of the original BiVO4, and under light conditions, the N-C 60 / BiVO4, P-C 60 / BiVO4, S-C 60 / BiVO4, B-C 60 The resistance values of B-C 60 / BiVO4 under light conditions are the smallest, which shows that in the application of photoelectrocatalysis, B-doped C 60 compounded with BiVO4 can maximize the improvement of the photoelectron transmission capacity of the catalyst material under visible light. Due to the existence of a large number of active sites on the surface of the composite catalyst, the current and intensity level of the anode peak are increased. The composite of carbon-based materials can enhance the adsorption capacity of ·OH on the material, which in turn improves the surface activity of C 60 / BVO nanocomposite, thereby improving the catalytic performance of the entire photoelectrocatalyst. The I-t curve B-C 60 / BiVO4 has the highest photocurrent, which is consistent with the phenomenon.

[0114] To sum up, the present application adopts chemical vapor deposition method to dope different metal elements into fullerene, and then uses in-situ hydrothermal growth to form a uniform, dense and firm catalyst film on FTO, thereby obtaining a more stable and high-activity photoelectrolysis water electrode. The preparation method of the present application is simple, low in cost, and can realize large-scale electrode preparation. Therefore, the present application has a wide application prospect in the field of photoelectrolysis water technology.

[0115] It should be emphasized that: the above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present application still belongs to the scope of the technical solutions of the present application.

Claims

1. A method for photoelectrochemical water splitting using non-metallic element-doped fullerene-composite bismuth vanadate, characterized in that, Includes the following steps: Step s1: Clean the conductive substrate to remove impurities from its surface; Step s2: Fullerene powder is doped with non-metallic elements by chemical vapor deposition to generate modified fullerene. Step s3: Dissolve the modified fullerene treated in step s2 in solvent A; dissolve the Bi source and V source in solvent B, and stir to prepare a catalyst slurry; Step s4: After mixing the catalyst slurry prepared in step s3, transfer it to the chemical reaction device. Then, place the conductive substrate cleaned in step s1 with the conductive side facing down in the chemical reaction device and perform hydrothermal in-situ growth to prepare a photoelectrocatalytic thin film. Step s5: After the reaction in step s4 is completed, wait for the chemical reaction apparatus to cool naturally to room temperature, remove the conductive substrate and place it in a high-temperature heating device for heating and calcination to obtain the photoelectric water splitting electrode. The non-metallic elements in step s2 include one or more of nitrogen, phosphorus, sulfur, boron, fluorine, and chlorine. In step s3, solvent A includes one or more of toluene, benzene, carbon tetrachloride, and cumene; solvent B includes one or more of ethylene glycol, ethanol, methanol, isopropanol, and deionized water.

2. The method for photoelectrochemical water splitting of non-metallic element-doped fullerene composite bismuth vanadate according to claim 1, characterized in that, In step s3, the Bi source includes one or more of bismuth nitrate pentahydrate, bismuth subcarbonate dihydrate, and bismuth sulfate, and the V source includes one or more of ammonium metavanadate, vanadium pentoxide, and vanadium acetylacetonate.

3. The method for photoelectrochemical water splitting of non-metallic element-doped fullerene composite bismuth vanadate according to claim 1, characterized in that, In step s1, the conductive substrate includes: fluorine-doped silica conductive glass (FTO), indium tin oxide transparent conductive film glass (ITO), and stainless steel plate. In step s2, the fullerene is C 60 .

4. The method for photoelectrochemical water splitting of non-metallic element-doped fullerene composite bismuth vanadate according to claim 1, characterized in that, In step s4, the chemical reaction apparatus includes: a reaction vessel; In step s5, the high-temperature heating device includes a muffle furnace.

5. The method for photoelectrochemical water splitting of non-metallic element-doped fullerene composite bismuth vanadate according to claim 1, characterized in that, In step s1, the cleaning step involves sequentially ultrasonically bathing the conductive substrate with deionized water, acetone, isopropanol, and ethanol for 5-20 minutes.

6. The method for photoelectrochemical water splitting of non-metallic element-doped fullerene composite bismuth vanadate according to claim 1, characterized in that, In step s2, the fullerene and non-metallic elements are thoroughly mixed and placed in a tube furnace and evacuated 2-5 times. Then, the mixture is calcined at 300-1000℃ for 1-4 hours under N2 atmosphere.

7. The method for photoelectrochemical water splitting of non-metallic element-doped fullerene composite bismuth vanadate according to claim 1, characterized in that, In step s4, the hydrothermal time is 6–18 hours and the hydrothermal temperature is 120–200°C.

8. The method for photoelectrochemical water splitting of non-metallic element-doped fullerene composite bismuth vanadate according to claim 1, characterized in that, In step s5, the temperature of the high-temperature heating device is set to 350-500℃, the heating rate is 5-10℃ / min, and the calcination time is 1-4h.

9. The method for photoelectrochemical water splitting of non-metallic element-doped fullerene composite bismuth vanadate according to claim 1, characterized in that, The dimensions of the conductive substrate include: 1cm*1cm, 1cm*2cm, 2cm*2cm, and 2cm*3cm.

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