Preparation method and application of hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 Z-type heterojunction photoelectrocatalyst

Abstract

The application relates to a preparation method and application of a hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 Z-type heterojunction photoelectrocatalyst, and belongs to the technical field of high-value chemical products and catalyst production. 24 The ZIF-67@Mo-CoFe PBA cube is obtained by reacting Co(NO3)2.6H2O, cetyltrimethylammonium bromide and 2-methylimidazole, then adding K3[Fe(CN)6] to react, and then adding (NH4)6Mo7O The Mo2N-Co3O4@Fe2O3 / PVDF hydrophobic electrode prepared from the Mo2N-Co3O4@Fe2O3 cube can be used for photoelectrocatalytic preparation of H2O2. The application has the characteristics of simplicity, high efficiency, low cost and high absorption in the full spectral range. The prepared hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 Z-type heterojunction photoelectrocatalyst has the advantages of large specific surface area, suitable energy band structure, high catalytic activity and stability, good hydrophobicity, high separation efficiency of photo-generated electron-hole pairs, fast interface charge transport efficiency, high H2O2 production in photoelectrocatalytic preparation, and can be applied to the fields of photoelectrocatalytic preparation of H2O2 and degradation of organic matters.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high value-added chemicals and catalyst production, and particularly relates to a preparation method and application of a hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 Z-type heterojunction photoelectrocatalyst. BACKGROUND

[0002] Photoelectrocatalysis technology is considered to be one of the most promising methods for solar energy conversion. The PEC system has higher photoexcited electron / hole separation efficiency under the condition of an external bias, and the synthesized sustainable chemicals are easier to separate and collect; on the other hand, the PEC system driven by sunlight has lower power consumption.

[0003] Hydrogen peroxide (H2O2) is one of the most important 100 chemicals in the world, and is an environmentally friendly, renewable, clean chemical oxidant with only water and oxygen as by-products, which is widely used in biological science (disinfection), environmental remediation (organic decomposition) and chemical processing (pulp bleaching) and other industries. Traditional industrial synthesis methods of H2O2 are limited in practical application due to complex process, high cost and large amount of toxic waste by-products.

[0004] Photoelectrochemical (PEC) oxygen reduction reaction (ORR) for producing H2O2 as a mild green method has attracted extensive attention due to its environmental friendliness and cost-effectiveness. The effective combination of light and electricity can selectively prevent the occurrence of the side reaction of four-electron oxygen reduction to generate O2 which is thermodynamically more favorable, and the catalyst is easier to recover, which is a cleaner and more sustainable production method. At present, photoelectrocatalysis technology has been widely used in various catalytic fields, including H2, O2 and CO2 reduction, but due to the high oxidation potential and two by-products O2 and ·OH when generating H2O2 by photoelectrochemical water oxidation on the photoanode, the catalyst required for H2O2 production needs to have both strong oxidation ability and certain selectivity. In addition, the recombination of photo-generated electrons and holes leads to low photo quantum yield, which also limits the application of photoelectrocatalysis technology in practice.

[0005] The research finds that the hollow double-shell nano-structure heterojunction catalyst can induce multiple light reflection and scattering to enhance light absorption, provide high specific surface area, gas adsorption capacity and contact interface between the catalyst and electrolyte, and thus can be applied to efficient PEC ORR to produce H2O2. By adjusting the wettability of the electrode surface to build a gas-liquid-solid three-phase interface, the problems of poor oxygen solubility and high mass transfer resistance can be solved, which can effectively improve the performance of photoelectrocatalytic production of H2O2. Therefore, designing and building a semiconductor material with hollow double-shell structure, large specific surface area, good light absorption capacity and suitable energy band position will be a very effective strategy for producing H2O2.

[0006] The catalyst is difficult to selectively prevent the side reaction of four-electron oxygen reduction to generate O2 which is more favorable in thermodynamics, and the foam nickel loaded with the catalyst is used as a working electrode, a platinum wire is used as a counter electrode, Ag / AgCl is used as a reference electrode, the voltage is controlled by an electrochemical workstation, and a xenon lamp is used for light to prepare H2O2 by photoelectrocatalysis. SUMMARY

[0007] One of the purposes of the present application is to provide a preparation method of a hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 Z-type heterojunction photoelectrocatalyst which has a higher full-spectrum response and can effectively separate photo-generated electrons and holes.

[0008] The second purpose of the present application is to provide a method for preparing H2O2 by using a hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 Z-type heterojunction photoelectrocatalyst.

[0009] The technical scheme adopted by the present application is:

[0010] A preparation method of a hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 Z-type heterojunction photoelectrocatalyst, comprising the following steps:

[0011] 1) A mixed aqueous solution of Co(NO3)2.6H2O and hexadecyl bromide ammonium is quickly injected into an aqueous solution of 2-methyl imidazole, stirred at room temperature for 20 minutes, centrifuged and collected, washed with ethanol for 3 times, and then dried in a vacuum oven at 60 DEG C for 24 hours to obtain ZIF-67 nanocubes;

[0012] 2) The ZIF-67 nanocubes obtained in step 1) are ultrasonically dispersed in ethanol to form solution A; K3[Fe(CN)6] is dissolved in water to form a transparent yellow solution B; then solution B is quickly injected into solution A, continuously stirred at room temperature for 3 hours, and then the product is collected by centrifugation, washed with deionized water and ethanol for 3 times, and then dried in a vacuum oven at 60 DEG C for 24 hours to obtain ZIF-67@CoFe PBA cubes;

[0013] 3) dispersing the ZIF-67@CoFe PBA cubes obtained in step 2) into ethanol, dispersing (NH4)6Mo7O 24 ·4H2O into deionized water, continuously stirring the above two dispersions for 4 hours to complete the ion exchange reaction, then centrifuging to collect the product, washing with a large amount of deionized water and ethanol, and drying in a vacuum oven at 60°C for 24 hours to obtain ZIF-67@Mo-CoFe PBA cubes;

[0014] 4) calcining the ZIF-67@Mo-CoFe PBA cubes obtained in step 3) to obtain hollow double-shell Mo2N-Co3O4@Fe2O3 cubes;

[0015] 5) dispersing the hollow double-shell Mo2N-Co3O4@Fe2O3 cubes obtained in step 4) in anhydrous ethanol, ultrasonicating for 15 minutes, then adding polyvinylidene fluoride and ultrasonicating for 20 minutes, then heating the mixture to a paste in a water bath at 80°C, dividing it into two parts, coating them on the upper and lower sides of the pretreated nickel foam in the form of a sandwich, and placing them in the mold of a tablet press for pressing, then calcining to obtain a hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 photoelectrocatalyst.

[0016] Further, in the above preparation method, in step 1), the mass concentration ratio of Co(NO3)2·6H2O: hexadecyltrimethylammonium bromide: 2-methylimidazole is 406:7:908.

[0017] Further, in the above preparation method, in step 2), the mass concentration ratio of ZIF-67 nanocubes: K3[Fe(CN)6] is 22:300.

[0018] Further, in the above preparation method, in step 3), the mass concentration ratio of ZIF-67@CoFe PBA cubes: (NH4)6Mo7O 24 ·4H2O is 1:2.

[0019] Further, in the above preparation method, in step 4), the calcination process is heating to 500°C at a heating rate of 1°C·min -1 and holding for 2 hours in an air atmosphere.

[0020] Further, in the above preparation method, in step 5), the mass concentration ratio of hollow double-shell Mo2N-Co3O4@Fe2O3 cubes: polyvinylidene fluoride is 10:7.

[0021] Further, in the above preparation method, in step 5), the calcination process is heating to 300°C and holding for 1 hour in an air atmosphere.

[0022] The application of the hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 photoelectrocatalyst prepared by the preparation method in any of the above in the photoelectrocatalytic preparation of H2O2.

[0023] Further, the application and the method described above comprise the following steps:

[0024] 1) The hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 photoelectrocatalyst is used as a working electrode, a platinum sheet is used as a counter electrode, and Ag / AgCl is used as a reference electrode, which are placed in a reaction container to form a three-electrode system;

[0025] 2) Under the conditions of a bias voltage of-0.8 V and an ambient temperature of 25 DEG C, the three-electrode system is inserted into a reactor containing 20 mL of 0.1 mM KOH solution, and high-purity O2 is pumped into the electrolyte solution to saturation under dark conditions, and H2O2 is catalytically synthesized under photoelectric driving.

[0026] Further, the application and the method described above comprise the following steps:

[0027] 1) The hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 photoelectrocatalyst is used as a photoelectric cathode, and Co3O4 is used as an anode to construct a two-electrode battery system for simultaneous synthesis of H2O2;

[0028] 2) The cathode electrolyte solution is 20 mL of 0.1 mM KOH solution saturated with O2, the anode electrolyte solution is 20 mL of 0.1 M KHCO3 solution saturated with N2, and the two are separated by a proton exchange membrane, and H2O2 is catalytically synthesized under a bias voltage of-0.6 V.

[0029] The application has the following beneficial effects:

[0030] 1) The application constructs a hollow double-shell nanostructure, enhances light absorption through multiple reflection and scattering of light, improves the efficiency of photon capture, provides a high specific surface area, high gas adsorption capacity, and a large contact interface between the catalyst and the electrolyte, combines a suitable energy band structure to improve the separation efficiency of photo-generated electrons and holes, and solves the problems of poor oxygen solubility and high mass transfer resistance by constructing a gas-liquid-solid three-phase interface, thereby effectively improving the performance of photoelectrocatalytic production of H2O2.

[0031] 2、The application has the characteristics of being simple, efficient, low in cost and high in absorption in the full spectrum range, the prepared hydrophobic Mo2N-Co3O4@Fe2O3 Z-type heterojunction photoelectrocatalyst has the characteristics of hollow double-shell nanostructure, large specific surface area, suitable energy band structure, high catalytic activity, good hydrophobicity and catalytic stability, high separation efficiency of photo-generated electron-hole pairs, fast interface charge transport efficiency, high H2O2 production in photoelectrocatalytic preparation, and can be applied to the fields of photoelectrocatalytic preparation of H2O2 and degradation of organic matter. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is the SEM (A) and TEM (B) diagram of the hollow double-shell Mo2N-Co3O4@Fe2O3 Z-type heterojunction photoelectrocatalyst.

[0033] Figure 2 is the XRD diagram of Co3O4, Co3O4@Fe2O3 and Mo2N-Co3O4@Fe2O3 prepared in Example 1.

[0034] Figure 3 is the diffuse reflectance spectrum diagram of Co3O4, Co3O4@Fe2O3 and Mo2N-Co3O4@Fe2O3 prepared in Example 1 in the full spectrum range.

[0035] Figure 4 is the SEM of Mo2N-Co3O4@Fe2O3 (A) and Mo2N-Co3O4@Fe2O3 / PVDF (B) prepared in Example 1 and the corresponding hydrophobic angle diagram.

[0036] Figure 5 is a comparison diagram of the production of photoelectrocatalytic synthesis of H2O2 by different catalyst materials.

[0037] Figure 6 is a comparison diagram of the production of photoelectrocatalytic synthesis of H2O2 by Mo2N-Co3O4@Fe2O3 and Mo2N-Co3O4@Fe2O3 / PVDF under different potentials.

[0038] Figure 7 is a diagram of the production of photoelectrocatalytic synthesis of H2O2 by Mo2N-Co3O4@Fe2O3 / PVDF photoelectrocathode coupled with Co3O4 anode. DETAILED DESCRIPTION

[0039] The application will be further described below in combination with specific embodiments.

[0040] Preparation of hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 Z-type heterojunction photoelectrocatalyst in Example 1

[0041] 1) Weigh 58 mg Co(NO3)2·6H2O and dissolve it in 2 mL of deionized water containing 1 mg hexadecyl ammonium bromide. Quickly inject the mixed solution into 14 mL of 2-methylimidazole (908 mg) aqueous solution, stir at room temperature for 20 minutes, collect by centrifugation, wash 3 times with ethanol, and dry in a vacuum oven at 60 °C for 24 hours to obtain ZIF-67 nanocubes.

[0042] 2) Weigh 22 mg of ZIF-67 nanocubes obtained in step 1) and ultrasonically disperse them in 15 mL of ethanol to form solution A; at the same time, weigh 100 mg of K3[Fe(CN)6] and dissolve it in 5 mL of H2O to form a transparent yellow solution B; then rapidly inject solution B into solution A, stir continuously at room temperature for 3 hours, then centrifuge to collect the product, wash it 3 times with deionized water and ethanol, and dry it in a vacuum oven at 60 °C for 24 hours to obtain ZIF-67@CoFe PBA cubes;

[0043] 3) Mix 50 mg of the ZIF-67@CoFe PBA cube obtained in step 2) with 25 mg of (NH4)6Mo7O 24 • 4H2O was dispersed in 40 mL of ethanol and 10 mL of deionized water, respectively. The two dispersions were stirred for 4 hours to complete the ion exchange reaction. Then, the product was collected by centrifugation, washed with a large amount of deionized water and ethanol, and dried in a vacuum oven at 60 °C for 24 hours to obtain ZIF-67@Mo-CoFe PBA cubes.

[0044] 4) The ZIF-67@Mo-CoFe PBA cube obtained in step 3) is incubated in air at 1℃·min. -1 Heating to 500℃ at a rising rate and holding for 2 hours yielded a hollow double-shell Mo2N-Co3O4@Fe2O3 cube;

[0045] 5) Weigh 10 mg of the hollow double-shell Mo2N-Co3O4@Fe2O3 cube obtained in step 4) and disperse it in 500 μL of anhydrous ethanol. Sonicate for 15 minutes, then add 7 mg of polyvinylidene fluoride (PVDF) and sonicate for another 20 minutes. Then heat the mixture in a water bath at 80°C until it becomes a paste. Divide it into two parts and coat them in a sandwich form on the top and bottom sides of a pretreated nickel foam (2 cm × 2 cm). Place them in a mold of a tablet press and press them. Then anneal at 300°C for 1 hour to obtain a hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 photocatalyst (Mo2N-Co3O4@Fe2O3 / PVDF).

[0046] For comparison, the temperature was 1℃·min in air. -1The ZIF-67 nanocubes obtained in step 1) and the ZIF-67@CoFe PBA cubes obtained in step 2) were heated to 500 DEG C at a heating rate of 2 DEG C / min and kept for 2 hours to prepare comparative materials Co3O4 and Co3O4@Fe2O3, respectively.

[0047] Figure 1 Fig. 1 is SEM (A) and TEM (B) diagrams of hollow double-shell Mo2N-Co3O4@Fe2O3 Z-type heterojunction photocatalyst, from which it can be seen that the prepared Mo2N-Co3O4@Fe2O3 has a hollow double-shell structure, and the surface is rough and porous.

[0048] Figure 2 Fig. 2 is XRD diagrams of Co3O4, Co3O4@Fe2O3 and Mo2N-Co3O4@Fe2O3, from which it can be seen that the prepared Mo2N-Co3O4@Fe2O3 is a ternary composite of Co3O4, Fe2O3 and Mo2N.

[0049] Figure 3 Fig. 3 is diffuse reflectance spectra of Co3O4, Co3O4@Fe2O3 and Mo2N-Co3O4@Fe2O3 in the full spectral range, from which it can be seen that Mo2N-Co3O4@Fe2O3 exhibits strong light absorption in the visible and near-infrared light range.

[0050] Figure 4 Fig. 4 is SEM and corresponding hydrophobicity angle diagrams of Mo2N-Co3O4@Fe2O3 (A) and Mo2N-Co3O4@Fe2O3 / PVDF (B), from which it can be seen that Mo2N-Co3O4@Fe2O3 / PVDF maintains the cubic morphology, and the hydrophobicity is significantly improved.

[0051] Application of hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 photocatalyst in photoelectrocatalytic preparation of H2O2

[0052] The method is as follows:

[0053] 1) The hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 photocatalyst prepared in Example 1 was used as a working electrode, a platinum sheet was used as a counter electrode, and Ag / AgCl was used as a reference electrode, which were placed in a reaction container to form a three-electrode system;

[0054] 2) Under the conditions of -0.8 V bias, ambient temperature 25℃, using 300W xenon lamp to simulate sunlight irradiation, xenon lamp λ≥420nm, the three-electrode system was inserted into the reactor containing 20 mL 0.1 mM KOH solution, high-purity O2 was pumped into the electrolyte solution to saturation under dark conditions, and 0.5 mL of reaction solution was taken out every 30 min during the photoelectric-driven catalytic reaction. The generated H2O2 was detected by spectroscopy.

[0055] (I) Effect of different catalyst materials on H2O2 production

[0056] 1) 10 mg of Co3O4, Co3O4@Fe2O3 and Mo2N-Co3O4@Fe2O3 were weighed respectively and dispersed in 500 μL of anhydrous ethanol, ultrasonic for 15 minutes, then the mixture was heated to paste in a water bath at 80℃, and then divided into two parts, coated on the upper and lower sides of the pretreated foam nickel (2 cm x 2 cm) in the form of a sandwich, and placed in the mold of the tablet press for pressing. The prepared electrodes were annealed at 300℃ for 1 hour to prepare three different electrodes;

[0057] 2) Mo2N-Co3O4@Fe2O3 / PVDF hydrophobic electrode and the three different electrodes obtained in step 1) were used as the working electrode, platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode, which were placed in the reaction vessel to form a three-electrode system. In 20 mL 0.1 mM KOH solution, high-purity O2 was pumped into the electrolyte solution to saturation under dark conditions, and different working electrodes were used to catalyze the synthesis of H2O2 under photoelectric drive.

[0058] The results are shown in Figure 5 Mo2N-Co3O4@Fe2O3 photoelectrocatalytic synthesis of H2O2 yield was significantly higher than that of Co3O4 and Co3O4@Fe2O3, mainly due to the higher O2 concentration in the cavity of the porous hollow double-shell structure. At the same time, Mo2N-Co3O4@Fe2O3 / PVDF hydrophobic electrode as a photoelectrocathode, the yield of photoelectrocatalytic synthesis of H2O2 was the highest, and the yield reached 12.8 mM after 3 hours of catalysis, mainly due to the synergistic effect of the porous hollow double-shell structure and the gas-liquid-solid three-phase reaction interface, which accelerated the mass transfer and adsorption of O2, and promoted the photoelectrocatalytic synthesis of H2O2.

[0059] (II) Effect of different potentials on H2O2 production

[0060] In 20 mL 0.1 mM KOH solution, high-purity O2 was pumped into the electrolyte solution under dark conditions to saturation, and Mo2N-Co3O4@Fe2O3 / PVDF and Mo2N-Co3O4@Fe2O3 working electrodes were driven at different potentials, respectively, to catalyze the reaction for 1 hour to synthesize H2O2.

[0061] The results are shown in Figure 6 Mo2N-Co3O4@Fe2O3 / PVDF at different potentials, and the Faraday efficiency is higher than that of Mo2N-Co3O4@Fe2O3, which is mainly due to the fact that the hydrophobic treatment is beneficial to the rapid mass transfer of O2, which can accelerate the kinetics of photoelectrocatalytic synthesis of H2O2, thereby achieving higher photoelectrocatalytic synthesis of H2O2 at lower current density. At a potential of-0.8 V, Mo2N-Co3O4@Fe2O3 / PVDF obtains the best H2O2 production (9.3 mM) and Faraday efficiency (90%).

[0062] Example 3 Application of hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 photoelectrocatalyst in photoelectrocatalytic preparation of H2O2

[0063] A two-electrode battery system for simultaneous synthesis of H2O2 was constructed using Mo2N-Co3O4@Fe2O3 / PVDF hydrophobic electrode as the photoelectrocathode and Co3O4 as the anode. The cathode electrolyte solution was 20 mL O2-saturated KOH solution (0.1 mM), and the anode electrolyte solution was 20 mL N2-saturated KHCO3 solution (0.1 M), separated by a proton exchange membrane. H2O2 was synthesized by catalytic reaction for 2 hours at an applied voltage of-0.6 V.

[0064] The results are shown in Figure 7 The H2O2 production on the two electrodes increased with time, and after 2 hours of catalytic reaction, the cathode H2O2 concentration reached 11.4 mM; the anode H2O2 concentration reached 235 μM, and the co-electrolysis process achieved simultaneous production of value-added chemicals on the cathode and anode.

Claims

1. A method for preparing a hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 Z-type heterojunction photocatalyst, characterized in that, Includes the following steps: 1) A mixed aqueous solution of Co(NO3)2•6H2O and hexadecylammonium bromide was rapidly injected into an aqueous solution of 2-methylimidazole, stirred at room temperature for 20 minutes, collected by centrifugation, washed three times with ethanol, and dried in a vacuum oven at 60°C for 24 hours to obtain ZIF-67 nanocubes. 2) The ZIF-67 nanocubes obtained in step 1) were ultrasonically dispersed in ethanol to form solution A; K3[Fe(CN)6] was dissolved in H2O to form a transparent yellow solution B; then solution B was rapidly injected into solution A, and the mixture was stirred continuously at room temperature for 3 hours. The product was then collected by centrifugation, washed three times with deionized water and ethanol, and dried in a vacuum oven at 60°C for 24 hours to obtain ZIF-67@CoFe PBA cubes. 3) Disperse the ZIF-67@CoFe PBA cubes obtained in step 2) into ethanol, and then disperse (NH4)6Mo7O 24 • 4H2O was dispersed in deionized water, and the two dispersions were stirred continuously for 4 hours to complete the ion exchange reaction. Then, the product was collected by centrifugation, washed with a large amount of deionized water and ethanol, and dried in a vacuum oven at 60°C for 24 hours to obtain ZIF-67@Mo-CoFe PBA cubes. 4) The ZIF-67@Mo-CoFe PBA cube obtained in step 3) is calcined to obtain a hollow double-shell Mo2N-Co3O4@Fe2O3 cube; 5) The hollow double-shell Mo2N-Co3O4@Fe2O3 cubes obtained in step 4) were dispersed in anhydrous ethanol and sonicated for 15 minutes. Then, polyvinylidene fluoride was added and sonicated for another 20 minutes. The mixture was then heated in a water bath at 80°C until it became a paste. It was divided into two parts and coated on the upper and lower sides of the pretreated nickel foam in a sandwich manner. The mixture was then placed in a mold of a tablet press and pressed. Finally, it was calcined to obtain a hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 photocatalyst.

2. The preparation method according to claim 1, characterized in that, In step 1), the mass concentration ratio of Co(NO3)2•6H2O: cetylammonium bromide: 2-methylimidazole is 406:7:

908.

3. The preparation method according to claim 1, characterized in that, In step 2), the mass concentration ratio of ZIF-67 nanocubes to K3[Fe(CN)6] is 22:

300.

4. The preparation method according to claim 1, characterized in that, In step 3), according to the mass concentration ratio, ZIF-67@CoFe PBA cube: (NH4)6Mo7O 24 • The ratio of 4H2O to 1:

2.

5. The preparation method according to claim 1, characterized in that, In step 4), the calcination process is carried out in an air atmosphere at 1°C / min. -1 Heat to 500°C at a rising rate and hold for 2 hours.

6. The preparation method according to claim 1, characterized in that, In step 5), the mass concentration ratio of hollow double-shell Mo2N-Co3O4@Fe2O3 cube to polyvinylidene fluoride is 10:

7.

7. The preparation method according to claim 1, characterized in that, In step 5), the calcination process involves heating to 300°C in an air atmosphere and maintaining that temperature for 1 hour.

8. The application of the hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 photocatalyst prepared according to any one of claims 1-7 in the photocatalytic preparation of H2O2.

9. The application according to claim 8, characterized in that, The method includes the following steps: 1) A three-electrode system was formed by using a hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 photoelectrocatalyst as the working electrode, a platinum sheet as the counter electrode, and Ag / AgCl as the reference electrode in a reaction vessel. 2) Under the conditions of -0.8 V bias voltage and ambient temperature of 25°C, a 300 W xenon lamp was used to simulate sunlight irradiation. The xenon lamp λ≥420nm. The three-electrode system was inserted into a reactor containing 20 mL of 0.1 mM KOH solution. High-purity O2 was pumped into the electrolyte solution until saturation under dark conditions, and H2O2 was synthesized under photoelectric drive.

10. The application according to claim 8, characterized in that, The method includes the following steps: 1) A battery system for the simultaneous synthesis of H2O2 using a hydrophobic hollow double-shell Mo2N-Co3O4@Fe2O3 photoelectrocatalyst as the photocathode and Co3O4 as the anode was constructed. 2) The cathode electrolyte solution is 20 mL of 0.1 mM KOH solution saturated with O2, and the anode electrolyte solution is 20 mL of 0.1 M KHCO3 solution saturated with N2, separated by a proton exchange membrane. The reaction is catalytically synthesized into H2O2 under an applied voltage of -0.6 V.

Images