A co-production unit for non-polarized hydrogen peroxide and C3 chemicals based on a Pd-CuO / W-CuBi2O4 photocathode and its application.

Abstract

The application belongs to the field of photoelectrocatalysis, and relates to a non-biased hydrogen peroxide and C3 chemical co-production device based on a Pd-CuO / W-CuBi2O4 photo-cathode and application thereof. The application constructs a heterojunction photo-cathode composed of CuO and tungsten-doped CuBi2O4, and modifies palladium nanoparticles (Pd:CuO / W-CBO) for efficient and stable photoelectrochemical hydrogen peroxide generation. A non-biased photoelectrochemical system is constructed, which uses a Pd:CuO / W-CBO photo-cathode and a Pt / TiO2 anode to realize the synchronization of solar-driven hydrogen peroxide production and electrochemical glycerol oxidation to generate high-value chemicals. The hydrogen peroxide generated at the cathode can realize rapid water disinfection, and the work shows an expandable photoelectrochemical platform capable of stably generating solar-driven hydrogen peroxide and glycerol value-added at the same time, while generating renewable electricity.

Description

Technical Field

[0001] This invention belongs to the field of photoelectrocatalysis and relates to a photoelectrochemical device for converting oxygen into high-value-added chemicals. Background Technology

[0002] Hydrogen peroxide (H₂O₂) is an important environmentally friendly oxidant, widely used in wastewater treatment, pulp bleaching, and the synthesis of organic oxygen-containing compounds such as caprolactam and propylene oxide. Currently, industrial production of hydrogen peroxide mainly relies on the energy-intensive anthraquinone process, which is not only cumbersome but also carries the risk of explosion of the hydrogen-oxygen mixture. As a sustainable alternative, the photoelectrochemical two-electron oxygen reduction reaction (2e⁻² ... - ORR (Organic Oxygen Reduction) can generate hydrogen peroxide with relatively low environmental impact and inherent safety. Semiconductor materials (such as metal sulfides (e.g., Cu3BiS3) and transition metal oxides (e.g., NiO)) have shown potential in photoelectrochemical two-electron oxygen reduction reactions, but they face challenges such as competition from four-electron oxygen reduction pathways and slow charge transfer, which limit the selectivity and yield of hydrogen peroxide. Therefore, developing semiconductors with customized catalytic surfaces to achieve efficient and highly selective hydrogen peroxide production remains a key challenge.

[0003] CuBi₂O₄ is a promising p-type oxide photocathode with a suitable bandgap (1.6 eV) and favorable band structure. These properties enable its efficient activation of small molecules (such as H₂O₂, CO₂, and O₂) and facilitate high-performance photoelectrochemical oxygen reduction reactions at low potentials. For example, Zhang et al. reported a novel Au / CuBi₂O₄ / PtSe₂ van der Waals heterojunction photoelectrode at 0.5 V. RHE The following was achieved: -0.59 mA cm⁻¹ -2 The NaCo₂O₄ / CuBi₂O₄ photoelectrode achieved a photocurrent density and a hydrogen peroxide Faraday efficiency of 35%, thanks to the charge modulation effect of the van der Waals heterojunction, which promoted electron transfer kinetics. Combining photothermoelectric and photoelectric effects, the NaCo₂O₄ / CuBi₂O₄ photoelectrode generates an internal thermoelectric potential to suppress carrier recombination, achieving a hydrogen peroxide yield of 192.9 μmol / L. However, current CuBi₂O₄-based photoelectrodes suffer from fundamental limitations: slow bulk charge transfer kinetics and poor corrosion resistance. This severely hinders the production performance of photoelectrochemical hydrogen peroxide, especially during long-term operation. Furthermore, constructing a bias-free photoelectrochemical device for simultaneous solar-driven hydrogen peroxide production and the synthesis of high-value chemicals at the anode places stringent demands on efficiency and durability. Therefore, developing a bias-free CuBi₂O₄ photocathode presents challenges in terms of both activity and stability for efficient hydrogen peroxide generation. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a device for the co-production of hydrogen peroxide and C3 chemicals without polarization based on a Pd-CuO / W-CuBi2O4 photocathode and its application.

[0005] The technical solution of this invention is implemented as follows:

[0006] On the one hand, this invention provides a method for preparing a Pd-CuO / W-CuBi2O4 photocathode, the steps of which are:

[0007] (1) Preparation of CuBi2O4 semiconductor: An ethanol solution containing 0.2-0.25 M p-benzoquinone was stirred until transparent, while a 0.3-0.5 M potassium iodide (KI) solution was prepared and its pH was adjusted to 1-2 with nitric acid (HNO3). Subsequently, 0.04-0.05 mol of bismuth nitrate pentahydrate (Bi(NO3)3・5H2O) was dissolved in the solution and mixed with the p-benzoquinone solution. Bismuth oxyiodide (BiOI / FTO) was prepared by electrodeposition at -0.1 V vs. Ag / AgCl for 300 seconds on a fluorine-doped tin oxide (FTO) substrate.

[0008] (2) Doping of W: The BiOI / FTO electrode was immersed in a 0.2 M copper acetate monohydrate (Cu (CH3COO)2・H2O) solution. Copper was electrodeposited on the BiOI / FTO electrode at -0.3 V vs. Ag / AgCl for 50~200 seconds. After deposition, the electrode was rinsed with deionized water and dried in air. After the electrode was dry, 50~200 μL of 1.5~5 mM ammonium metatungstate solution was added dropwise to the BiOI / FTO electrode. The electrode was then allowed to stand and dry in air. Subsequently, it was annealed at 400~500℃ for 2~3 hours in an oxygen atmosphere to prepare the W-CuBi2O4 electrode.

[0009] (3) Formation of CuO layer and annealing treatment: under argon atmosphere (20 sccm, 3 mTorr, base pressure about 10 -4 ~10 -5 Cu was sputtered onto W-CBO at a power of 150 W for 5-9 minutes in Pa, followed by oxygen annealing at 400-500 °C for 100-120 minutes to obtain a CuO / W-CuBi2O4 electrode.

[0010] (4) Loading and annealing of Pd nanoparticles: The electrode was immersed in 1~5mM palladium acetylacetonate (Pd (acac)2) solution for 3min, dried in air and then annealed at 300~450℃ in an oxygen atmosphere for 100~120min to finally obtain Pd-CuO / W-CuBi2O4 electrode.

[0011] Secondly, the present invention provides a Pd-CuO / W-CuBi2O4 photocathode prepared using the above-described method.

[0012] Thirdly, the present invention provides a device for the co-production of undetermined hydrogen peroxide and C3 chemicals, including a reaction tank, a workstation, a stirring device, and a gas path device. The reaction tank includes a cathode reaction tank and an anode reaction tank. The cathode reaction tank uses the aforementioned Pd-CuO / W-CuBi2O4 photocathode as the cathode, and the anode reaction tank uses Pt / TiO2 as the anode. The reaction tanks are separated by a proton exchange membrane. The cathode electrolyte is 0.1 M KOH, and the anode electrolyte is 0.1 M KOH and 0.5 M glycerol.

[0013] The preparation steps of the above Pt / TiO2 are as follows:

[0014] ① Commercial titanium mesh is ultrasonically cleaned, then sequentially cleaned with deionized water, ethanol, and acetone, and then dried for later use.

[0015] ② Dissolve 0.5 g / mL chloroplatinic acid (H2PtCl6) in 3 wt% hydrochloric acid solution to form a homogeneous mixture. Then transfer the mixture to a reaction vessel, immerse a titanium mesh in the mixture, and react at 200℃ for 6 hours to obtain Pt / TiO2.

[0016] The volume ratio of the chloroplatinic acid solution to the hydrochloric acid solution is 1-5:2400.

[0017] Fourthly, the present invention provides a method for generating C3 chemicals at the anode and hydrogen peroxide at the cathode in a cogeneration unit under illumination conditions.

[0018] Preferably, the above-mentioned illumination conditions are 50-200 mW / cm². -2 Sunlight shines on it.

[0019] The present invention has the following beneficial effects:

[0020] (1) The average Faraday efficiency of the Pd-CuO / W-CuBi2O4 photocathode constructed in this application exceeds 90%, and the onset potential is 1.1 V. RHE At 0.7 V RHE It can operate stably for more than 50 hours, exhibiting excellent electrocatalytic activity stability and product selectivity. Through in-situ characterization and theoretical calculations, it was confirmed that Pd-CuO / W-CuBi2O4 achieves highly active and selective hydrogen peroxide generation by inhibiting the dissociation of *OOH and promoting its electron transfer.

[0021] (2) This application uses Pt / TiO2 as the anode electrocatalyst and replaces the traditional oxygen evolution reaction (OER) with the glycerol oxidation reaction (GOR), which effectively reduces the energy consumption of the entire photoelectrochemical system and gives the anode reaction additional high-value product output.

[0022] (3) This application successfully constructed a bias-free coupled photoelectrochemical (PEC) system of Pd-CuO / W-CuBi2O4 photocathode and Pt / TiO2 anode, achieving -3.75 mA cm⁻¹ under simulated solar illumination. -2 The photocurrent density was optimized to achieve a hydrogen peroxide yield of 375.6 μmol / h. -1 The yield of C3 product was 152.6 μmol / h. -1 This achievement represents a leading level in the unbiased PEC system, validating the system's scalability and potential industrialization prospects. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 These are scanning electron microscope images; where ab represents CuBi₂O₄, cd represents W-CuBi₂O₄, ef represents CuO / W-CuBi₂O₄ and gh represents Pd-CuO / W-CuBi₂O₄.

[0025] Figure 2 The images are transmission electron microscopy (TEM) images and EDX spectra; where ag represents Pd-CuO / W-CuBi2O4; and h represents the EDX spectrum of Pd-CuO / W-CuBi2O4.

[0026] Figure 3 The LSV curves of the photocathode materials in O2-saturated 0.1 M KOH and the yield of H2O2 produced by the photocathodes are shown. Among them, a is the LSV curve of CuBi2O4, W-CuBi2O4, CuO / W-CuBi2O4, and Pd-CuO / W-CuBi2O4, b is the H2O2 FE of four photocathodes CuBi2O4, W-CuBi2O4, CuO / W-CuBi2O4, and Pd-CuO / W-CuBi2O4, and c is the H2O2 yield of four photocathodes CuBi2O4, W-CuBi2O4, CuO / W-CuBi2O4, and Pd-CuO / W-CuBi2O4.

[0027] Figure 4 The stability and elemental composition of the photocathode were tested; where a represents CuBi₂O₄, W-CuBi₂O₄, CuO / W-CuBi₂O₄, and Pd-CuO / W-CuBi₂O₄ at 0.7 V. RHE The stability of Pd-CuO / W-CuBi2O4 under 5 hours is shown in Figure b, which represents the electrolyte ICP element content test after 5 hours of it measurement.

[0028] Figure 5 The hydrogen peroxide yield and Faraday efficiency (FE) of the photocathode were measured; where a represents the hydrogen peroxide yield and Faraday efficiency (FE) accumulated by Pd-CuO / W-CuBi2O4 during 20 hours of operation, and b represents the hydrogen peroxide yield and Faraday efficiency (FE) of Pd-CuO / W-CuBi2O4 over a 30-hour cycle.

[0029] Figure 6 The image represents the characterization of the photocathode, where a is the in-situ infrared spectrum of CuBi2O4, b is the in-situ infrared spectrum of Pd-CuO / W-CuBi2O4, c is the in-situ Raman spectrum of CuBi2O4, and d is the in-situ Raman spectrum of Pd-CuO / W-CuBi2O4.

[0030] Figure 7 The image shows the characterization of the photoanode; where ac is the scanning electron microscope image of Pt / TiO2 and df is the transmission electron microscope image of Pt / TiO2.

[0031] Figure 8 Performance and yield tests of the unbiased hydrogen peroxide and C3 chemical co-production unit of this application; where a is the LSV curve of Pd-CuO / W-CuBi2O4 photocathode and Pt / TiO2 anode in 0.1 M potassium hydroxide + 0.5 M glycerol, b is the chronoamperometry test of unbiased Pd-CuO / W-CuBi2O4‖Pt / TiO2, with the surface areas of the cathode and anode being 10 cm² and 1 cm², respectively, and c is the yield of hydrogen peroxide and C3 products in five cycles, using a photocathode (10 cm²) and a photoanode (1 cm²), respectively.

[0032] Figure 9 Selectivity exploration for an unbiased hydrogen peroxide and C3 chemical co-production unit; where a is a schematic diagram of the operation scheme: multiple membranes separate hydrogen peroxide production (cathode) from glycerol oxidation (anode); b is the Faraday efficiency of five hydrogen peroxide cycles, each lasting 2 hours; c is the enhancement of selectivity by adjusting hydrogen peroxide permeation using various membranes (PEM, CEM, AEM and NoM).

[0033] Figure 10The time-varying bacterial inactivation efficiency of hydrogen peroxide generated by PEC against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] Unless otherwise specified, the experimental methods used in the following experimental examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0036] This embodiment provides a preparation step for a Pd-CuO / W-CuBi2O4 photocathode:

[0037] (1) Preparation of CuBi2O4 semiconductor: An ethanol solution containing 0.23 M p-benzoquinone was stirred until transparent, while a 0.4 M potassium iodide (KI) solution was prepared and its pH was adjusted to 1.7 with nitric acid (HNO3). Subsequently, 0.04 mol of bismuth nitrate pentahydrate (Bi(NO3)3・5H2O) was dissolved in the potassium iodide (KI) solution and mixed with the ethanol solution of p-benzoquinone, so that the molar ratio of bismuth nitrate pentahydrate, potassium iodide and p-benzoquinone was 1:40:23. Bismuth oxyiodide (BiOI / FTO) was prepared by electrodeposition at -0.1 V vs. Ag / AgCl for 300 seconds on a fluorine-doped tin oxide (FTO) substrate.

[0038] (2) Doping of W: The BiOI / FTO electrode was immersed in a 0.2 M copper acetate monohydrate (Cu (CH3COO)2・H2O) solution. Copper was electrodeposited on the BiOI / FTO electrode for 100 seconds at -0.3 V vs. Ag / AgCl. After deposition, the electrode was rinsed with deionized water and dried in air. After the electrode was dried, 100 μL of 5 mM ammonium metatungstate solution was added dropwise to the BiOI / FTO electrode. The electrode was then allowed to stand and dry in air. Subsequently, it was annealed at 450 °C for 3 hours in an oxygen atmosphere to prepare the W-CuBi2O4 electrode.

[0039] (3) Formation of CuO layer and annealing treatment: under argon atmosphere (20 sccm, 3 mTorr, base pressure about 10 - 4Cu was sputtered onto W-CBO at a power of 150 W for 7 minutes, followed by oxygen annealing at 450 °C for 100 minutes to obtain a CuO / W-CuBi2O4 electrode.

[0040] (4) Loading and annealing of Pd nanoparticles: The electrode was immersed in a 3mM palladium acetylacetonate (Pd (acac)2) solution for 3 min, dried in air and then annealed at 400℃ in an oxygen atmosphere for 100 min to finally obtain the Pd-CuO / W-CuBi2O4 electrode.

[0041] This embodiment provides a preparation step for a Pd-CuO / W-CuBi2O4 photocathode:

[0042] (1) Preparation of CuBi2O4 semiconductor: An ethanol solution containing 0.22 M p-benzoquinone was stirred until transparent, while a 0.3 M potassium iodide (KI) solution was prepared and its pH was adjusted to 1.2 with nitric acid (HNO3). Subsequently, 0.04 mol of bismuth nitrate pentahydrate (Bi(NO3)3・5H2O) was dissolved in the potassium iodide (KI) solution and mixed with the ethanol solution of p-benzoquinone, so that the molar ratio of bismuth nitrate pentahydrate, potassium iodide and p-benzoquinone was 1:30:22. Bismuth oxyiodide (BiOI / FTO) was prepared by electrodeposition at -0.1 V vs. Ag / AgCl for 300 seconds on a fluorine-doped tin oxide (FTO) substrate.

[0043] (2) Doping of W: The BiOI / FTO electrode was immersed in a 0.2 M copper acetate monohydrate (Cu (CH3COO)2・H2O) solution. Copper was electrodeposited on the BiOI / FTO electrode for 200 seconds at -0.3 V vs. Ag / AgCl. After deposition, the electrode was rinsed with deionized water and dried in air. After the electrode was dry, 100 μL of 3.5 mM ammonium metatungstate solution was added dropwise to the BiOI / FTO electrode. The electrode was then allowed to stand and dry in air. Subsequently, it was annealed at 400 °C for 3 hours in an oxygen atmosphere to prepare the W-CuBi2O4 electrode.

[0044] (3) Formation of CuO layer and annealing treatment: under argon atmosphere (20 sccm, 3 mTorr, base pressure approximately 0.4 × 10⁻⁶). -4 Cu was sputtered onto W-CBO at a power of 150 W for 5 minutes, followed by oxygen annealing at 400 °C for 150 minutes to obtain a CuO / W-CuBi2O4 electrode.

[0045] (4) Loading and annealing of Pd nanoparticles: The electrode was immersed in a 3mM palladium acetylacetonate (Pd (acac)2) solution for 3 min, dried in air and then annealed at 400℃ in an oxygen atmosphere for 110 min to finally obtain the Pd-CuO / W-CuBi2O4 electrode.

[0046] This embodiment provides a preparation step for a Pd-CuO / W-CuBi2O4 photocathode:

[0047] (1) Preparation of CuBi2O4 semiconductor: An ethanol solution containing 0.2 M p-benzoquinone was stirred until transparent, while a 0.5 M potassium iodide (KI) solution was prepared and its pH was adjusted to 1.9 with nitric acid (HNO3). Subsequently, 0.04 mol of bismuth nitrate pentahydrate (Bi(NO3)3・5H2O) was dissolved in the potassium iodide (KI) solution and mixed with the ethanol solution of p-benzoquinone, so that the molar ratio of bismuth nitrate pentahydrate, potassium iodide and p-benzoquinone was 1:50:20. Bismuth oxyiodide (BiOI / FTO) was prepared by electrodeposition at -0.1 V vs. Ag / AgCl for 200 seconds on a fluorine-doped tin oxide (FTO) substrate.

[0048] (2) Doping of W: The BiOI / FTO electrode was immersed in a 0.2 M copper acetate monohydrate (Cu (CH3COO)2・H2O) solution. Copper was electrodeposited on the BiOI / FTO electrode at -0.3 V vs. Ag / AgCl for 50 seconds. After deposition, the electrode was rinsed with deionized water and dried in air. After the electrode was dried, 150 μL of 2.5 mM ammonium metatungstate solution was added dropwise to the BiOI / FTO electrode. The electrode was then allowed to stand and dry in air. Subsequently, it was annealed at 450 °C for 2.5 hours in an oxygen atmosphere to prepare the W-CuBi2O4 electrode.

[0049] (3) Formation of CuO layer and annealing treatment: under argon atmosphere (20 sccm, 3 mTorr, base pressure approximately 0.3 × 10⁻⁶), the CuO layer was formed and annealed. -4 Cu was sputtered onto W-CBO at a power of 150 W for 8 minutes, followed by oxygen annealing at 500 °C for 110 minutes to obtain a CuO / W-CuBi2O4 electrode.

[0050] (4) Loading and annealing of Pd nanoparticles: The electrode was immersed in a 3mM palladium acetylacetonate (Pd (acac)2) solution for 3 min, dried in air and then annealed at 400℃ in an oxygen atmosphere for 100 min to finally obtain the Pd-CuO / W-CuBi2O4 electrode.

[0051] This embodiment provides a preparation step for a Pd-CuO / W-CuBi2O4 photocathode:

[0052] (1) Preparation of CuBi2O4 semiconductor: An ethanol solution containing 0.2 M p-benzoquinone was stirred until transparent, while a 0.3 M potassium iodide (KI) solution was prepared and its pH was adjusted to 1.1 with nitric acid (HNO3). Subsequently, 0.04 mol of bismuth nitrate pentahydrate (Bi(NO3)3・5H2O) was dissolved in the potassium iodide (KI) solution and mixed with the ethanol solution of p-benzoquinone, so that the molar ratio of bismuth nitrate pentahydrate, potassium iodide and p-benzoquinone was 1:30:20. Bismuth oxyiodide (BiOI / FTO) was prepared by electrodeposition at -0.1 V vs. Ag / AgCl for 300 seconds on a fluorine-doped tin oxide (FTO) substrate.

[0053] (2) Doping of W: The BiOI / FTO electrode was immersed in a 0.2 M copper acetate monohydrate (Cu (CH3COO)2・H2O) solution. Copper was electrodeposited on the BiOI / FTO electrode for 200 seconds at -0.3 V vs. Ag / AgCl. After deposition, the electrode was rinsed with deionized water and dried in air. After the electrode was dry, 50 μL of 1.5 mM ammonium metatungstate solution was added dropwise to the BiOI / FTO electrode. The electrode was then allowed to stand and dry in air. Subsequently, it was annealed at 500 °C for 2 hours in an oxygen atmosphere to prepare the W-CuBi2O4 electrode.

[0054] (3) Formation of CuO layer and annealing treatment: under argon atmosphere (20 sccm, 3 mTorr, base pressure approximately 0.8 × 10⁻⁶). -4 Cu was sputtered onto W-CBO at a power of 150 W for 9 minutes, followed by oxygen annealing at 400 °C for 120 minutes to obtain a CuO / W-CuBi2O4 electrode.

[0055] (4) Loading and annealing of Pd nanoparticles: The electrode was immersed in a 2mM palladium acetylacetonate (Pd (acac)2) solution for 3 min, dried in air and then annealed at 400℃ in an oxygen atmosphere for 110 min to finally obtain the Pd-CuO / W-CuBi2O4 electrode.

[0056] This embodiment provides a preparation step for a Pd-CuO / W-CuBi2O4 photocathode:

[0057] (1) Preparation of CuBi2O4 semiconductor: An ethanol solution containing 0.24 M p-benzoquinone was stirred until transparent, while a 0.5 M potassium iodide (KI) solution was prepared and its pH was adjusted to 2 with nitric acid (HNO3). Subsequently, 0.04 mol of bismuth nitrate pentahydrate (Bi(NO3)3・5H2O) was dissolved in the potassium iodide (KI) solution and mixed with the ethanol solution of p-benzoquinone, so that the molar ratio of bismuth nitrate pentahydrate, potassium iodide and p-benzoquinone was 1:50:24. Bismuth oxyiodide (BiOI / FTO) was prepared by electrodeposition at -0.1 V vs. Ag / AgCl for 400 seconds on a fluorine-doped tin oxide (FTO) substrate.

[0058] (2) Doping of W element: The BiOI / FTO electrode was immersed in a 0.2 M copper acetate monohydrate (Cu (CH3COO)2・H2O) solution, and copper was electrodeposited on the BiOI / FTO electrode for 150 seconds at -0.3 V vs. Ag / AgCl. After deposition, the electrode was rinsed with deionized water and dried in air. After the electrode was dried, 150 μL of 2 mM ammonium metatungstate solution was added dropwise to the BiOI / FTO electrode. The electrode was then allowed to stand and dry in air, and then annealed at 450 °C for 3 hours in an oxygen atmosphere to prepare the W-CuBi2O4 electrode.

[0059] (3) Formation of CuO layer and annealing treatment: under argon atmosphere (20 sccm, 3 mTorr, base pressure approximately 0.5 × 10⁻⁶), -4 Cu was sputtered onto W-CBO at a power of 150 W for 6 minutes, followed by oxygen annealing at 430 °C for 100 minutes to obtain a CuO / W-CuBi2O4 electrode.

[0060] (4) Loading and annealing of Pd nanoparticles: The electrode was immersed in 4 mM palladium acetylacetone (Pd (acac)2) solution for 3 min, dried in air and then annealed at 450℃ in an oxygen atmosphere for 120 min to finally obtain Pd-CuO / W-CuBi2O4 electrode.

[0061] This comparative example provides a preparation procedure for a CuBi2O4 photocathode:

[0062] (1) Preparation of CuBi2O4 semiconductor: An ethanol solution containing 0.23 M p-benzoquinone was stirred until transparent, while a 0.4 M potassium iodide (KI) solution was prepared and its pH was adjusted to 1.7 with nitric acid (HNO3). Subsequently, 0.04 mol of bismuth nitrate pentahydrate (Bi(NO3)3・5H2O) was dissolved in the solution and mixed with the p-benzoquinone solution to make the molar ratio of bismuth nitrate pentahydrate, potassium iodide and p-benzoquinone 1:40:23. Bismuth oxyiodide (BiOI), i.e. BiOI / FTO electrode, was prepared by electrodeposition at -0.1 V vs. Ag / AgCl for 300 seconds on a fluorine-doped tin oxide (FTO) substrate. Next, copper was electrodeposited on a BiOI / FTO electrode for 100 seconds in a 0.2 M copper acetate monohydrate (Cu(CH3COO)2・H2O) solution at -0.3 V vs. Ag / AgCl, followed by annealing at 450 °C for 3 hours in an oxygen atmosphere to prepare a CuBi2O4 electrode.

[0063] This comparative example provides a preparation procedure for a W-CuBi2O4 photocathode:

[0064] (1) Preparation of CuBi2O4 semiconductor: An ethanol solution containing 0.23 M p-benzoquinone was stirred until transparent, while a 0.4 M potassium iodide (KI) solution was prepared and its pH was adjusted to 1.7 with nitric acid (HNO3). Subsequently, 0.04 mol of bismuth nitrate pentahydrate (Bi(NO3)3・5H2O) was dissolved in the solution and mixed with the p-benzoquinone solution. Bismuth oxyiodide (BiOI / FTO) was prepared by electrodeposition at -0.1 V vs. Ag / AgCl for 300 seconds on a fluorine-doped tin oxide (FTO) substrate.

[0065] (2) Doping of W: The BiOI / FTO electrode was immersed in a 0.2 M copper acetate monohydrate (Cu (CH3COO)2・H2O) solution. Copper was electrodeposited on the BiOI / FTO electrode for 100 seconds at -0.3 V vs. Ag / AgCl. After deposition, the electrode was rinsed with deionized water and dried in air. After the electrode was dried, 100 μL of 5 mM ammonium metatungstate solution was added dropwise to the BiOI / FTO electrode. The electrode was then allowed to stand and dry in air. Subsequently, it was annealed at 450 °C for 3 hours in an oxygen atmosphere to prepare the W-CuBi2O4 electrode.

[0066] This comparative example provides a preparation procedure for a Pd-CuO / W-CuBi2O4 photocathode:

[0067] (1) Preparation of CuBi2O4 semiconductor: An ethanol solution containing 0.23 M p-benzoquinone was stirred until transparent, while a 0.4 M potassium iodide (KI) solution was prepared and its pH was adjusted to 1.7 with nitric acid (HNO3). Subsequently, 0.04 mol of bismuth nitrate pentahydrate (Bi(NO3)3・5H2O) was dissolved in the solution and mixed with the p-benzoquinone solution. Bismuth oxyiodide (BiOI / FTO) was prepared by electrodeposition at -0.1 V vs. Ag / AgCl for 300 seconds on a fluorine-doped tin oxide (FTO) substrate.

[0068] (2) Doping of W: The BiOI / FTO electrode was immersed in a 0.2 M copper acetate monohydrate (Cu (CH3COO)2・H2O) solution. Copper was electrodeposited on the BiOI / FTO electrode for 100 seconds at -0.3 V vs. Ag / AgCl. After deposition, the electrode was rinsed with deionized water and dried in air. After the electrode was dried, 100 μL of 5 mM ammonium metatungstate solution was added dropwise to the BiOI / FTO electrode. The electrode was then allowed to stand and dry in air. Subsequently, it was annealed at 450 °C for 3 hours in an oxygen atmosphere to prepare the W-CuBi2O4 electrode.

[0069] (3) Formation of CuO layer and annealing treatment: under argon atmosphere (20 sccm, 3 mTorr, base pressure about 10 - 4 Cu was sputtered onto W-CBO at a power of 150 W for 7 minutes in Pa, followed by oxygen annealing at 450 °C for 100 minutes to obtain a CuO / W-CuBi2O4 electrode.

[0070] This embodiment provides a preparation step for a Pt / TiO2 anode:

[0071] (1) The commercial titanium mesh (TF) was ultrasonically cleaned, and then cleaned with deionized water, ethanol and acetone in sequence and dried for later use.

[0072] (2) Dissolve 20 μL of 0.5 g / mL chloroplatinic acid (H2PtCl6) in 24 mL of 3 wt% hydrochloric acid solution to form a homogeneous mixture. Then transfer the solution to a hydrothermal autoclave, immerse a titanium mesh in it, and react at 200 °C for 6 hours to finally form Pt / TiO2.

[0073] This embodiment provides a preparation step for a Pt / TiO2 anode:

[0074] (1) The commercial titanium mesh (TF) was ultrasonically cleaned, and then cleaned with deionized water, ethanol and acetone in sequence and dried for later use.

[0075] (2) Dissolve 10 μL of 0.5 g / mL chloroplatinic acid (H2PtCl6) in 24 mL of 3 wt% hydrochloric acid solution to form a homogeneous mixture. Then transfer the solution to a hydrothermal autoclave, immerse a titanium mesh in it, and react at 200 °C for 6 hours to finally form Pt / TiO2.

[0076] This embodiment provides a preparation step for a Pt / TiO2 anode:

[0077] (1) The commercial titanium mesh (TF) was ultrasonically cleaned, and then cleaned with deionized water, ethanol and acetone in sequence and dried for later use.

[0078] (2) Dissolve 30 μL of 0.5 g / mL chloroplatinic acid (H2PtCl6) in 24 mL of 3 wt% hydrochloric acid solution to form a homogeneous mixture. Then transfer the solution to a hydrothermal autoclave, immerse a titanium mesh in it, and react at 200 °C for 6 hours to finally form Pt / TiO2.

[0079] This embodiment provides a preparation step for a Pt / TiO2 anode:

[0080] (1) The commercial titanium mesh (TF) was ultrasonically cleaned, and then cleaned with deionized water, ethanol and acetone in sequence and dried for later use.

[0081] (2) Dissolve 40 μL of 0.5 g / mL chloroplatinic acid (H2PtCl6) in 24 mL of 3 wt% hydrochloric acid solution to form a homogeneous mixture. Then transfer the solution to a hydrothermal autoclave, immerse a titanium mesh in it, and react at 200 °C for 6 hours to finally form Pt / TiO2.

[0082] This embodiment provides a preparation step for a Pt / TiO2 anode:

[0083] (1) The commercial titanium mesh (TF) was ultrasonically cleaned, and then cleaned with deionized water, ethanol and acetone in sequence and dried for later use.

[0084] (2) Dissolve 50 μL of 0.5 g / mL chloroplatinic acid (H2PtCl6) in 24 mL of 3 wt% hydrochloric acid solution to form a homogeneous mixture. Then transfer the solution to a hydrothermal autoclave, immerse a titanium mesh in it, and react at 200 °C for 6 hours to finally form Pt / TiO2.

[0085] A preparation step for a TiO2 anode:

[0086] (1) The commercial titanium mesh (TF) was ultrasonically cleaned, and then cleaned with deionized water, ethanol and acetone in sequence and dried for later use.

[0087] (2) Transfer 24 mL of 3 wt% hydrochloric acid solution to a hydrothermal autoclave, immerse the titanium mesh in it, and react at 200℃ for 6 hours to finally form TiO2.

[0088] The Pd-CuO / W-CuBi2O4 prepared in Example 1, the CuBi2O4 prepared in Comparative Example 1, the W-CuBi2O4 prepared in Comparative Example 2, and the CuO / W-CuBi2O4 prepared in Comparative Example 3 were compared. Scanning electron microscopy (SEM) images showed that all samples exhibited a nanosheet morphology. Figure 1 (Ah). The surface of the tungsten-doped CuBi₂O₄ nanosheets is smoother than that of the original CuBi₂O₄, indicating that doping leads to defect suppression. Both CuO / W-CuBi₂O₄ and Pd-CuO / W-CuBi₂O₄ exhibit a CuO capping layer of approximately 150 nm thickness, which may be related to enhanced charge transport and corrosion resistance. Transmission electron microscopy (TEM) observation of Pd-CuO / W-CuBi₂O₄ shows a clear interface between W-CuBi₂O₄ and CuO. Figure 2 (a) and (b). In Pd-CuO / W-CuBi2O4, metallic Pd nanoparticles with a diameter of approximately 10 nm are uniformly dispersed and attached to the CuO surface. These nanoparticles serve as key catalytic sites for the two-electron oxygen reduction reaction. The lattice spacings are 0.318 nm and 0.252 nm, respectively, corresponding to the (211) crystal plane of CuBi2O4 and the (002) crystal plane of CuO. Figure 2 (c and d), while the lattice spacing of 0.257 nm corresponds to the (200) plane of Pd ( Figure 2 (f and g). Elemental mapping by energy-dispersive X-ray spectroscopy (EDS) using transmission electron microscopy confirmed the distribution of Cu, Bi, O, W, and Pd. Figure 2 (h). These analyses validate the structural design of Pd-CuO / W-CuBi2O4, in which the synergistic effect between W doping, CuO heterojunction, and Pd nanoparticles achieves efficient and stable 2e-ORR performance.

[0089] Photoelectrochemical measurements were performed in a closed H-type cell using a three-electrode system: a Pd-CuO / W-CuBi₂O₄ working electrode, an Ag / AgCl reference electrode, and a platinum foil counter electrode. A Nafion 117 membrane separated the working and counter electrodes. Oxygen reduction measurements were performed for 0.5 hours at different application potentials using 0.1 M KOH as the electrolyte. Prior to testing, the working electrode chamber was purged with oxygen at a rate of 30 mL / min for at least 30 minutes. Illumination was provided by an AM1.5G simulator with a power of 100 mW / cm². -2 The recorded potentials are based on an Ag / AgCl reference electrode and can be converted to a reversible hydrogen electrode (RHE) scale using the Nernst equation: E RHE =E (Ag / AgCl） +0.197 +0.0591 * pH. Using Ce 4+ The evolution of hydrogen peroxide was determined by colorimetric method. During irradiation, equal aliquots (5 mL) were collected using a syringe and mixed with 4.5 mL of 0.5 M sulfuric acid aqueous solution and 0.5 mL of 1 M sulfuric acid containing 2 mM Ce(SO4)2, followed by shaking for 2 minutes. The resulting solution was analyzed by UV-Vis spectroscopy. The Faraday efficiency of hydrogen peroxide can be calculated using the following formula:

[0090] = ×100%;

[0091] = ×100%.

[0092] We evaluated the performance of CuBi₂O₄, W-CuBi₂O₄, CuO / W-CuBi₂O₄, and Pd-CuO / W-CuBi₂O₄ photocathodes under AM 1.5G illumination (100 mW cm⁻¹). -2 The photoelectrochemical (PEC) hydrogen peroxide generation performance in O2-saturated 0.1 M potassium hydroxide was investigated. Notably, Pd-CuO / W-CuBi2O4 exhibited high efficiency at 0.7 V. RHE It reached 1.99 mA cm -2 The highest photocurrent density exceeds that of CuBi2O4 (0.39 mA cm⁻¹). -2 ), W-CuBi2O4 (0.96 mA cm⁻¹) -2 ) and CuO / W-CuBi2O4 (1.37 mA cm -2 Its forward initiation potential is 1.08 V. RHE The value is significantly lower than that of CuO / W-CuBi2O4 (1.03 V). RHE W-CuBi2O4 (0.99 V)RHE ) and CuBi2O4 (0.94 V) RHE ). Figure 3 a) We adopt Ce 4+ The yield of hydrogen peroxide was quantitatively analyzed by colorimetry. All photocathodes were used at 0.6–0.8 V. RHE The Faraday efficiency (FEs) remains stable across the entire potential range. Figure 3 (b) At this potential, the average FE of CuBi₂O₄ is ~30%, indicating a preferential selection of 4-electron ORR reactions over 2-electron ORR reactions. In contrast, the average FE of W-CuBi₂O₄ and CuO / W-CuBi₂O₄ reach 52% and 78%, respectively, confirming that tungsten doping and heterojunction formation can promote the selective 2-electron ORR reaction of hydrogen peroxide. The deposition of palladium nanoparticles further enhances the hydrogen peroxide yield at 0.7 V on Pd-CuO / W-CuBi₂O₄. RHE The average potential FE reached 91%, with a peak FE of ~93%. This material also exhibited the highest hydrogen peroxide yield, which continued to increase as the potential decreased, reaching 0.4 V under optimized conditions. RHE The time was 1.14 μmol cm⁻²min⁻¹, significantly exceeding that of CuO / W-CuBi₂O₄ (0.69), W-CuBi₂O₄ (0.30 μmol cm⁻²min⁻¹) and CuBi₂O₄ (0.11 μmol cm⁻²min⁻¹). Figure 3 (c)

[0093] Within the test potential range, Pd-CuO / W-CuBi2O4 exhibits the highest charge transfer rate constant (Ktrans) and the lowest charge recombination rate constant (Krec). Figure 4 (a) At 0.7 V RHE At this time, the Ktrans and Krec values ​​of Pd-CuO / W-CuBi2O4 were 50.3 s⁻¹ and 3.4 s⁻¹, respectively. These kinetic parameters indicate accelerated charge transfer and suppressed charge recombination, consistent with the improvement in photoelectrochemical performance. Furthermore, within the potential range of 0.4 to 0.9 V, the Ktrans / (Ktrans+Krec) ratios of both CuO / W-CuBi2O4 and W-CuBi2O4 were higher than CBO, which has a positive effect on improving photoelectrochemical conversion efficiency. Long-term operational stability is a key indicator for evaluating the practical application value of photoelectrodes. Figure 4As shown in Figure b, both the CuO / W-CuBi2O4 and Pd-CuO / W-CBO systems maintained stable photocurrent densities for over 50 hours. In contrast, the performance of the W-CuBi2O4 and CuBi2O4 systems significantly declined, retaining only 34.6% and 22.4% of their initial photocurrent densities after 5 hours of operation, respectively. The durability of the photoelectrode mainly depends on its chemical stability against electrolyte corrosion and the strong adhesion of the catalyst. Inductively coupled plasma (ICP) analysis of the electrolyte showed that the dissolution of copper and bismuth in the Pd-CuO / W-CuBi2O4 system was minimal after 5 hours of operation. The CBO system, however, exhibited significant copper and bismuth loss. Figure 4 (c), which is consistent with the phenomenon of rapid performance degradation during the 2e-reduction oxygen evolution reaction (ORR) stage.

[0094] Figure 5 Figure a shows the concentration of hydrogen peroxide generated over time in Pd-CuO / W-CuBi2O4. The cumulative hydrogen peroxide concentration increased linearly in the first 16 hours, reaching 495.11 μmol. Thereafter, the accumulation rate began to decrease due to the decomposition of hydrogen peroxide in the electrolyte, but stabilized after 17 hours, indicating a steady state between hydrogen peroxide generation and decomposition. Correspondingly, the FE of hydrogen peroxide gradually decreased after 17 hours, consistent with the trend towards near-saturation concentration. Long-term cycling stability was evaluated through 30 consecutive 1-hour production cycles, with the electrolyte replaced after each cycle. Figure 5 (b) The photoelectrode maintained a stable photocurrent, FE>90%, and the hydrogen peroxide yield remained stable, with an average value of 0.51 μmol cm⁻¹. -2 min -1 .

[0095] This study used in-situ Fourier transform infrared spectroscopy (FTIR) to monitor the OOH intermediate generated by four photocathodes during the oxygen reduction reaction (ORR), revealing its reaction mechanism. Figure 6 (a and b). FTIR spectra at 1210 cm⁻¹ −1 The characteristic peak at this point corresponds to the O−O bond stretching vibration of the adsorbed OOH intermediate. The adsorption strength of the OOH intermediate in Pd-CuO / W-CuBi2O4 is significantly higher than that in CuO / W-CuBi2O4 and W-CuBi2O4, indicating that it has a superior 2e-ion adsorption capacity. - ORR selectivity. As the potential increases from 0.9 V... RHE Dropped to 0.4 V RHE The OOH intermediate signal intensity of Pd-CuO / W-CuBi2O4 increases with decreasing potential, which is consistent with the increase in hydrogen peroxide yield. Figure 3(c) The OOH intermediate vibrational signal of CuBi₂O₄ is weak, consistent with its poor hydrogen peroxide generation ability. Furthermore, CuBi₂O₄ and W-CuBi₂O₄ exhibit vibrational signals at 1145 cm⁻¹. -2 The presence of significant OH intermediate adsorption characteristics indicates that it preferentially undergoes 4e adsorption. - ORR. Although CuO / W-CuBi2O4 showed a weakened OH intermediate signal but an enhanced OOH intermediate signal, this indicates that the heterojunction induced 2e - ORR selectivity. In-situ Raman spectroscopy further supports these conclusions. Figure 6 (c and d). As the potential increases from 0.9 V... RHE As the concentration decreased to 0.4, the intensity of the OO intermediate adsorption stretching vibration and the OOH intermediate vibration mode gradually increased, confirming the occurrence of ORR. Although both Pd-CuO / W-CuBi2O4 and CuBi2O4 showed adsorption peaks for the OO intermediate, only Pd-CuO / W-CuBi2O4 exhibited a significant OOH intermediate vibration characteristic, confirming that its stability is critically determined by 2e-. - The unique capabilities of ORR intermediates.

[0096] Glycerol can be electrochemically oxidized into high-value-added C3 products (such as glyceryl oleate (GLA), dihydroxyacetone (DHA), and glyceraldehyde (GLD), opening a new sustainable development path for biomass resource utilization—utilizing low-value biodiesel byproducts while avoiding the high energy consumption of traditional synthesis processes. To simultaneously improve anodic charge transfer kinetics efficiency and produce high-value-added products, we developed a platinum-modified titanium dioxide catalyst (labeled Pt / TiO2) for the glycerol electrochemical oxidation reaction (GOR). Scanning electron microscopy characterization showed that the Pt / TiO2 material exhibited a uniform nanorod morphology. Figure 7 (c). TEM images show that the Pt nanoparticles decorated on TiO2 nanorods are highly dispersed, with a size of approximately 5 nm and lattice spacings of 0.225 nm and 0.237 nm, respectively corresponding to the (111) crystal plane of Pt(111) and the (004) crystal plane of TiO2. Figure 7 (df).

[0097] In recent years, achieving efficient and continuous co-production of hydrogen peroxide and high-value-added anode products under unbiased conditions has remained a significant challenge, primarily due to the insufficient activity and poor stability of the photoelectrode in the photoelectrochemical system. To address this, we have for the first time successfully integrated a Pd-CuO / W-CuBi2O4 photocathode with a Pt / TiO2 anode, achieving unbiased solar-driven production of hydrogen peroxide and high-value-added C3 products. Current-voltage curves validated the feasibility of unbiased operation at the crossover point. Figure 8(a) An initial operating current density of ~3.75 mA / cm² was obtained at a relative constant potential of ~0.51 V. The system assembled using a cation exchange membrane (CEM) maintained a stable current density for up to 10 hours during electrolyte replacement cycles. Furthermore, increasing the photocathode size to 10 cm² resulted in a six-fold increase in current density while maintaining stability for five 2-hour cycles. Figure 8 (b) Each cycle stably generates C3 products (containing GLA and GLD) and hydrogen peroxide. This scale-up system, requiring only sunlight exposure, achieves highly efficient conversion of hydrogen peroxide and glycerol, producing approximately 500.79 μmol of hydrogen peroxide and 255.47 μmol of C3 products per 2-hour cycle. Figure 8 (c) Successfully achieved the simultaneous synthesis of solar-powered hydrogen peroxide and the resource utilization of glycerol.

[0098] We enhance GOR selectivity by in-situ utilizing hydrogen peroxide generated at the cathode. This is achieved by employing different membrane materials ( Figure 9 In section a), we controlled the hydrogen peroxide permeation in the anode chamber. Four configurations were tested: proton exchange membrane (PEM), cation exchange membrane (CEM), anion exchange membrane (AEM), and no membrane (NoM). Given that hydrogen peroxide in alkaline media reacts with H₂O₂... − Given the presence of this form, we hypothesize that due to charge compatibility, hydrogen peroxide is preferentially permeated via AEM. Although all systems maintained operational stability during hydrogen peroxide production, the residual hydrogen peroxide levels varied significantly. Figure 9 (b) In the PEM / CEM system, hydrogen peroxide cross-permeation rarely occurs, and the selectivity of hydrogen peroxide reaches 85%. Figure 9 c), and Figure 3 The results in b are consistent. When using AEM, hydrogen peroxide undergoes moderate permeation, and the GLA selectivity increases from 20-21% in the PEM / CEM system to 56%. Figure 9 (c). In the NoM configuration, excessive cross-permeation of hydrogen peroxide causes C-C bond breakage, with the main byproduct being C1 formic acid (FA), resulting in a decrease in GLA selectivity to 26%.

[0099] We further validated the system's application potential in environmental remediation through on-site bacterial disinfection experiments. When using hydrogen peroxide generated by the unbiased system to sterilize *Escherichia coli*, *Staphylococcus aureus*, and *Pseudomonas aeruginosa*, the hydrogen peroxide generated after 10 hours of system operation demonstrated excellent performance. Figure 10The time-dependent inactivation kinetic curves shown indicate that, at the target concentration, all three pathogens were completely inactivated (>99%) within 180 minutes. This confirms the system's ability to achieve rapid hydrogen peroxide preparation and efficient water disinfection without the need for external chemical reagents. These results highlight the enormous application potential of solar-driven photoelectrochemical hydrogen peroxide technology in environmental remediation.

[0100] In summary, we have successfully developed a Pd-CuO / W-CuBi2O4 photocathode, which enables efficient and stable photoelectrochemical hydrogen peroxide production. By doping with tungsten and loading palladium nanoparticles, we significantly improved charge transport efficiency and optimized the two-electron reduction oxygen evolution reaction pathway, ultimately achieving a conversion efficiency exceeding 90% and maintaining operational stability for up to 50 hours. The copper oxide capping layer effectively suppressed the key degradation mechanism in copper-bismuth oxide (CuBi2O4)-based photoelectrodes—the dissolution of copper and bismuth. When this photocathode was coupled with a platinum / titanium dioxide anode, we constructed a bias-free series system that simultaneously enables solar-driven hydrogen peroxide synthesis and glycerol oxidation to produce high-value-added C3 products. By controlling the hydrogen peroxide permeability of the anion exchange membrane, selective extraction of glyceric acid (selectivity up to 56%) was achieved, while the hydrogen peroxide generated at the cathode efficiently disinfects water (pathogen inactivation rate exceeding 99.9%). This research pioneered a bias-free tandem photoelectrochemical system for the synthesis and resource utilization of solar-powered hydrogen peroxide, providing a sustainable solution for replacing energy-intensive industrial processes.

[0101] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a Pd-CuO / W-CuBi2O4 photocathode, characterized by, The steps are: (1) Dissolve bismuth nitrate pentahydrate in potassium iodide solution, then add p-benzoquinone ethanol solution to obtain a deposition solution, immerse the fluorine-doped tin oxide substrate in the deposition solution for electrodeposition to obtain a BiOI / FTO electrode; (2) Immerse the BiOI / FTO electrode in a copper acetate monohydrate solution for copper electrodeposition, then rinse with deionized water and dry in air, drop the ammonium metatungstate solution onto the BiOI / FTO electrode after the sample is completely dried, then let the electrode stand and dry in air, and the obtained electrode is subjected to oxygen annealing to obtain a W-CuBi2O4 electrode; (3) Sputter Cu on the W-CuBi2O4 electrode in an argon atmosphere, then perform oxygen annealing to obtain a CuO / W-CuBi2O4 electrode; (4) Immerse the CuO / W-CuBi2O4 electrode in a palladium acetylacetone solution, then take it out and dry in air, and the obtained product is subjected to oxygen annealing to obtain a Pd-CuO / W-CuBi2O4 electrode.

2. The method of producing a Pd-CuO / W-CuBi2O4photocathode according to claim 1, characterized by: In step (1), the concentration of the potassium iodide solution is 0.3-0.5 M, the pH is 1-2, and the concentration of the p-benzoquinone ethanol solution is 0.2-0.25 M; the molar ratio of bismuth nitrate pentahydrate, potassium iodide and p-benzoquinone is 1:30-50:20-25; and the electrodeposition conditions are: -0.1 V electrodeposition for 200-400 seconds.

3. The method for preparing a Pd-CuO / W-CuBi2O4 photocathode according to claim 1 or 2, characterized in that: In step (2), the copper electrodeposition conditions are: -0.3 V electrodeposition for 50-200 seconds; the concentration of the ammonium metatungstate solution is 1.5-5 mM, and the dropwise addition amount is 50-200 μL; the concentration of the copper acetate monohydrate solution is 0.2 M; and the oxygen annealing temperature is 400-500℃, and the time is 2-3 hours.

4. The method of producing a Pd-CuO / W-CuBi2O4 photocathode according to claim 3, characterized by: The conditions of the argon atmosphere in the step (3) are 20 sccm, 3 mTorr, base pressure is 10 -4 ~10 -5 Pa; the sputtering power is 150 W, the time is 5-9 minutes; the oxygen annealing temperature is 400-500 °C, the time is 100-120 minutes.

5. The method of claim 4, wherein the Pd-CuO / W-CuBi2O4 photocathode is prepared by the following steps: In step (4), the concentration of the palladium acetylacetone solution is 1-5 mM; the reaction conditions are: immersion for 3 minutes; the oxygen annealing temperature is 300-450℃, and the time is 100-120 minutes.

6. A Pd-CuO / W-CuBi2O4 photocathode prepared by the method of any one of claims 1-5.

7. An unbiased hydrogen peroxide and C3 chemicals co-production plant characterized by: The device comprises a reaction tank, a workstation, a stirring device and a gas path device, the reaction tank comprises a cathode reaction tank and an anode reaction tank, the cathode reaction tank uses the Pd-CuO / W-CuBi2O4 photocathode of claim 6 as a cathode, the anode reaction tank uses Pt / TiO2 as an anode, the reaction tank is separated by a proton exchange membrane, the cathode electrolyte is 0.1 M KOH, and the anode electrolyte is 0.1 M KOH and 0.5 M glycerol.

8. The unbiased hydrogen peroxide and C3 chemicals co-production apparatus of claim 7, wherein, The preparation steps of the Pt / TiO2 are: ① Commercial titanium mesh is cleaned by ultrasonic washing, then sequentially cleaned by deionized water, ethanol and acetone, and dried for standby use; ② 0.5 g / mL chloroplatinic acid solution is dissolved in 3 wt% hydrochloric acid solution to form a uniform mixture, then the mixture is transferred to a reaction kettle, and the titanium mesh is immersed in the mixture and reacted at 200℃ for 6 hours to obtain Pt / TiO2; The volume ratio of the chloroplatinic acid solution to the hydrochloric acid solution is 1-5:2400.

9. Use of the unbiased hydrogen peroxide and C3 chemicals co-production plant according to claim 7 or 8, characterized in that: The application is applied to produce C3 chemicals in the anode of a cogeneration device under illumination, and produce hydrogen peroxide in the cathode.

10. Use of an unbiased hydrogen peroxide and C3 chemicals co-production plant according to claim 9, characterized in that: The light conditions are 50-200 mW cm -2 The sun light is used for irradiation.

Images