A photocathode with a gas-solid-liquid three-phase interface, its preparation method, and its application in photoelectrocatalytic oxygen reduction to H2O2 production over a wide pH range.

Abstract

This invention belongs to the field of photoelectrocatalysis technology, specifically relating to a photocathode with a gas-solid-liquid three-phase interface, its preparation method, and its application in the photoelectrocatalytic reduction of oxygen to produce H2O2 over a wide pH range. The preparation steps are as follows: NaBH4, selenium powder, Co(NO3)2·6H2O, and Zr-Ni-TCPP are sequentially added to deionized water and sonicated; NaOH solution and ethanol solution are added dropwise, stirred, and reacted in a reaction vessel for 10-15 hours. After washing and drying, Co3Se4@Zr-Ni-TCPP is obtained. The photoelectrocatalytic material Co3Se4@Zr-Ni-TCPP prepared by this invention, through the introduction of Zr atoms for doping modification, successfully overcomes the limitation of traditional porphyrin-based MOFs, which can only catalyze efficiently in a narrow pH range. It can efficiently reduce O2 to produce H2O2 over a wider pH range, which helps promote the practical application of photoelectrocatalysis technology in the field of clean energy production.

Description

Technical Field

[0001] This invention belongs to the field of photoelectrocatalysis technology, specifically relating to a photocathode with a gas-solid-liquid three-phase interface, its preparation method, and its application in photoelectrocatalytic oxygen reduction to prepare H2O2 over a wide pH range. Background Technology

[0002] Hydrogen peroxide (H2O2) is a green and efficient inorganic oxidant. With its unique advantages of mild oxidation performance, reaction products consisting only of water and oxygen, and no secondary pollution, it is widely used in many core fields such as medical and health disinfection, textile and paper bleaching, industrial wastewater treatment, fine chemical synthesis, and new energy storage. With the rapid development of green chemistry and low-carbon environmental protection industries, the global demand for hydrogen peroxide has been increasing year by year, and large-scale, green, and low-cost hydrogen peroxide preparation technology has become a research hotspot in this field.

[0003] Currently, over 95% of hydrogen peroxide in the industrial sector is still produced using the anthraquinone process. While this technology is mature and can be scaled up, it suffers from numerous inherent drawbacks that severely restrict the industry's green development. Firstly, the anthraquinone process is complex, involving multiple steps such as anthraquinone hydrogenation, oxidation, extraction, purification, and solvent recovery. The production process requires high temperature and pressure conditions, resulting in high overall energy consumption, large carbon emissions per unit product, and low energy efficiency. Secondly, this process relies heavily on organic solvents and anthraquinone derivative systems, easily generating toxic pollutants such as organic waste liquids and solids during production. Anthraquinone is prone to non-selective hydrogenation degradation, and the catalyst is easily poisoned and deactivated, increasing material losses and equipment maintenance costs. Furthermore, the emitted organic pollutants cause continuous harm to water and soil ecosystems. With the increasing emphasis on energy shortages and low-carbon development, the utilization of solar energy resources has gained significant attention in the field of green chemistry. Photoelectrocatalysis technology can utilize solar energy to drive chemical reactions at ambient temperature and pressure. Combining the advantages of both photocatalysis and electrocatalysis, it features low energy consumption, high controllability, and no secondary pollution, making it an excellent green technology route for hydrogen peroxide production. Photoelectrocatalytic hydrogen peroxide production is based on the cathode two-electron ORR reaction, which includes two reaction pathways: the direct reduction pathway O2 + 2H + + 2e - = H2O2(E(O2 / H2O2) = +0.68 V vs. NHE), and the free radical stepwise reduction pathway O2 + e - → O2 - (E = -0.33 V vs. NHE), •O2 - + 2H + + e -→ H2O2 (E = +1.44 V vs. NHE). Currently, this technology still has significant shortcomings: traditional photoelectrodes suffer from severe carrier recombination, poor charge separation and migration efficiency, and low solar energy utilization; the system often requires the introduction of organic sacrificial agents, increasing costs and compromising green process characteristics; simultaneously, the material's visible light response is insufficient, and its overall catalytic performance fails to meet industrial requirements. Therefore, developing novel photoelectrode materials with high carrier separation efficiency, broad spectral response, and the ability to operate without sacrificial agents is key to overcoming existing technological bottlenecks.

[0004] Constructing semiconductor heterojunctions is a crucial method for improving the performance of photoelectrocatalytic hydrogen peroxide production. By combining semiconductor materials with different band structures to form an internal electric field, the directional migration of photogenerated carriers can be driven and their recombination suppressed. Simultaneously, the visible light response spectrum is broadened, and the interfacial charge transport channels are optimized, thereby effectively improving the catalytic efficiency and selectivity of hydrogen peroxide production. Furthermore, in traditional solid-liquid two-phase systems, the electrode is completely immersed in the electrolyte, relying solely on limited dissolved oxygen in the liquid phase for the reaction. Insufficient oxygen supply significantly restricts the ORR reaction kinetics, resulting in low hydrogen peroxide yield. In contrast, solid-liquid-gas three-phase interface systems can construct a unique catalytic microenvironment, effectively enriching gaseous oxygen and ensuring a sufficient supply of reaction substrates, thus significantly improving the selectivity of hydrogen peroxide production. While most current photoelectrocatalytic hydrogen peroxide production systems can achieve efficient two-electron oxygen reduction (ORR) in acidic environments, they generally suffer from narrow pH adaptation ranges, high equipment corrosion risks, and limited practical application scenarios. Therefore, developing photoelectrocatalytic systems that can adapt to a wide pH environment and exhibit stable performance is of great significance for enhancing the engineering application value of this technology.

[0005] To address the aforementioned issues, this patent constructs a Co3Se4@Zr-Ni-TCPP inorganic-organic semiconductor heterojunction, optimizing the band structure to accelerate the separation and migration of photogenerated charges. A stable gas-liquid-solid three-phase reaction interface is built using a hydrophobic carbon felt as a substrate, ensuring a sufficient oxygen supply and improving the selectivity of the hydrogen peroxide reaction. Furthermore, Zr doping modification broadens the pH range of the system. This invention achieves efficient, highly selective, wide pH adaptability, and long-term stable photoelectrocatalytic hydrogen peroxide production, effectively compensating for the shortcomings of single modification technologies and promoting the engineering application of green, low-cost hydrogen peroxide preparation technologies. Summary of the Invention

[0006] To solve the above problems, the technical solution of the present invention is as follows: a method for preparing a photocathode with a gas-solid-liquid three-phase interface, comprising the following steps:

[0007] Step 1: Preparation of Zr-Ni-TCPP: Ni(NO3)2·6H2O and PVP were dissolved in a mixed solvent to obtain solution A, and TCPP was dissolved in a mixed solvent to obtain solution B. Under vigorous stirring, solution B was slowly added dropwise to solution A, sonicated, and transferred to an autoclave for hydrothermal reaction. After washing and drying, Ni-TCPP was obtained. Ni-TCPP and ZrOCl2·8H2O were mixed and stirred vigorously, and benzaldehyde was added to the mixed solution. The mixture was stirred until completely dissolved and stirred for reaction. After washing and drying, Zr-Ni-TCPP was obtained.

[0008] Step 2: Preparation of Co3Se4@Zr-Ni-TCPP: NaBH4, selenium powder and Co(NO3)2·6H2O were ultrasonically dissolved in deionized water and stirred until completely dissolved. Zr-Ni-TCPP was then added, followed by dropwise addition of NaOH solution and ethanol solution. The mixture was stirred to ensure thorough mixing. The mixed solution was slowly transferred to a reaction vessel for hydrothermal reaction. After washing and drying, Co3Se4@Ni-TCPP was obtained.

[0009] In the above-mentioned method for preparing a photocathode with a gas-solid-liquid three-phase interface, in step 1, the mixed solvent is obtained by mixing DMF and ethanol at a volume ratio of 3:1.

[0011] In the above-mentioned method for preparing a photocathode with a gas-solid-liquid three-phase interface, in step 1, the mass ratio of Ni(NO3)2·6H2O:PVP:TCPP is 15:10:2.

[0012] In the above-mentioned method for preparing a photocathode with a gas-solid-liquid three-phase interface, in step 1, the hydrothermal reaction is carried out at 80-85℃ for 22-24 hours, and the stirring reaction is carried out at 90-85℃ for 3-6 hours.

[0013] In the above-mentioned method for preparing a photocathode with a gas-solid-liquid three-phase interface, in step 1, the mass ratio of Ni-TCPP:ZrOCl2·8H2O:benzaldehyde is 100:300:3.3.

[0014] In the above-mentioned method for preparing a photocathode with a gas-solid-liquid three-phase interface, in step 2, the molar ratio is NaBH4: selenium powder: Co(NO3)2·6H2O: Zr-Ni-TCPP = 12:4:3:1.52.

[0015] In the above-mentioned method for preparing a photocathode with a gas-solid-liquid three-phase interface, step 2 involves a hydrothermal reaction at 160-190℃ for 10-15 hours.

[0016] A photocathode with a gas-solid-liquid three-phase interface prepared according to the above preparation method.

[0017] The application of the above-mentioned photocathode with a gas-solid-liquid three-phase interface in the photoelectrocatalytic oxygen reduction to prepare H2O2 over a wide pH range.

[0018] The above application is performed as follows: a photocathode with a gas-solid-liquid three-phase interface is used as the working electrode, a Pt sheet as the counter electrode, and Ag / AgCl as the reference electrode, forming a three-electrode system. Na₂SO₄ solution is used as the electrolyte solution, and 10 mol / L... -1 The pH of the solution was adjusted to 2-13 using HClO4. A xenon lamp was used as the light source, and the reaction system was controlled at 14-16℃. Before the catalytic reaction began, O2 was continuously introduced into the solution under dark conditions. H2O2 was produced by photoelectrocatalysis under a bias voltage of -0.5V vs. Ag / AgCl.

[0019] The beneficial effects of this invention are:

[0020] 1. This invention constructs a Co3Se4@Zr-Ni-TCPP inorganic-organic heterojunction photoelectrode material with an S-shaped charge transfer path by in-situ loading Co3Se4 nanoparticles on the surface of Zr-Ni-TCPP metal-organic framework material using a simple solvothermal method. At the same time, a gas-solid-liquid three-phase reaction interface is constructed on a hydrophobic carbon felt as a substrate. Under visible light drive, the photoelectric synergistic effect is used to efficiently reduce O2 to produce H2O2.

[0021] 2. The photoelectrocatalytic material Co3Se4@Zr-Ni-TCPP prepared in this invention significantly improves the yield of H2O2 compared to single Co3Se4 or Zr-Ni-TCPP monomer materials. Simultaneously, through Zr doping modification, it successfully overcomes the limitation of traditional porphyrin-based MOFs being highly efficient only under strongly acidic conditions, maintaining excellent H2O2 yield across a wide pH range of 2-13. Furthermore, the three-phase interface constructed with hydrophobic carbon felt further enhances mass transfer efficiency, significantly improving the applicability and stability of photoelectrocatalytic oxygen reduction to hydrogen peroxide synthesis, thus contributing to the practical engineering application of photoelectrocatalysis technology in the field of clean energy production. Attached Figure Description

[0022] Figure 1 SEM images of Co3Se4 (a), Zr-Ni-TCPP (b), and Co3Se4@Zr-Ni-TCPP (c).

[0023] Figure 2 The XRD patterns are for Co3Se4, Zr-Ni-TCPP, and Co3Se4@Zr-Ni-TCPP.

[0024] Figure 3 XPS full spectra of Co3Se4, Zr-Ni-TCPP, and Co3Se4@Zr-Ni-TCPP.

[0025] Figure 4 LSV curves of Co3Se4, Zr-Ni-TCPP, and Co3Se4@Zr-Ni-TCPP photocathodes under different gases.

[0026] Figure 5 The graph shows the comparative test results of H2O2 preparation performance for Co3Se4, Zr-Ni-TCPP, and Co3Se4@Zr-Ni-TCPP photocathodes.

[0027] Figure 6 A comparison graph showing the effect of different Co3Se4 loadings on the production of H2O2 by Co3Se4@Zr-Ni-TCPP.

[0028] Figure 7 Hydrophobic angles of carbon paper (a), hydrophobic carbon felt (b), and PDMS-coated carbon felt (c) substrates.

[0029] Figure 8 The effect of the construction of the gas-solid-liquid three-phase interface on H2O2 production.

[0030] Figure 9 The yield of H2O2 at different solution pH values.

[0031] Figure 10 This is a free radical capture experiment.

[0032] Figure 11 A schematic diagram of the possible reaction mechanism for the photocatalytic reduction of oxygen to produce H2O2 using a Co3Se4@Zr-Ni-TCPP photocathode. Detailed Implementation

[0033] Example 1

[0034] Example 1: Preparation of Co3Se4 photoelectrode material and photocathode

[0035] Preparation of Co3Se4: Under the action of a magnetic stirrer, 12.0 mmol NaBH4, 4.0 mmol selenium powder and 3.0 mmol Co(NO3)2·6H2O were sequentially dissolved in 20.0 mL deionized water by ultrasonication. Then, 10.0 mL of 0.2 mol L2O solution was added dropwise to the mixed solution. -1The NaOH solution and 20.0 mL of ethanol solution were mixed and stirred to ensure thorough mixing. The mixture was then slowly transferred to a reaction vessel and reacted at 180 °C for 12 h. After washing and drying, brown powder Co3Se4 photoelectrode material was obtained.

[0036] Preparation of the working electrode: The hydrophobic carbon felt was cut into 2cm×3cm pieces for later use. 5mg of catalyst was dispersed in 0.5mL of deionized water, 6μL of naphthol solution was added, and after ultrasonic dispersion, it was uniformly deposited on the carbon felt (2cm×2cm). After drying, a uniform catalyst thin layer was formed to obtain the Co3Se4@Zr-Ni-TCPP photocathode, denoted as Co3Se4 / CF.

[0037] Example 2: Preparation of Zr-Ni-TCPP photoelectrode material and photocathode

[0038] Preparation of Zr-Ni-TCPP: First, a mixed solvent of DMF and ethanol with a volume ratio of 3:1 was prepared. 300.0 mg Ni(NO3)2·6H2O and 200.0 mg PVP were dissolved in 120 mL of the mixed solvent to obtain solution A. 40 mg TCPP was dissolved in 40 mL of the mixed solvent to obtain solution B. Solution B was slowly added dropwise to solution A under vigorous stirring. The mixture was sonicated for 10 min and then transferred to an autoclave and heated at 80 ℃ for 24 h. After washing and drying, the Ni-TCPP sample was obtained. 100.0 mg Ni-TCPP and 300.0 mg ZrOCl2·8H2O were added sequentially to a beaker containing 100.0 mL of DMF. Under vigorous stirring, 3.3 g benzaldehyde (BA) was added to the mixed solution, and stirring continued until completely dissolved, ensuring a homogeneous mixture. The mixture was then stirred in an oil bath at 90 ℃ for 5 h. After washing and drying, the Zr-Ni-TCPP photoelectrode material was obtained.

[0039] Preparation of the working electrode: The hydrophobic carbon felt was cut into 2cm×3cm pieces for later use. 5 mg of catalyst was dispersed in 0.5 mL of deionized water, 6 μL of naphthol solution was added, and after ultrasonic dispersion, it was uniformly deposited on the carbon felt (2cm×2cm). After drying, a uniform catalyst thin layer was formed to obtain the Zr-Ni-TCPP photocathode, denoted as Zr-Ni-TCPP / CF.

[0040] Example 3: Preparation of Co3Se4@Zr-Ni-TCPP photoelectrode material and photocathode

[0041] Preparation of Co3Se4@Zr-Ni-TCPP: 12.0 mmol NaBH4, 4.0 mmol selenium powder, and 3.0 mmol Co(NO3)2·6H2O were sequentially ultrasonically dissolved in 20.0 mL deionized water and stirred until completely dissolved. Then, 1.52 mmol Zr-Ni-TCPP was added to the solution, followed by dropwise addition of 10.0 mL of 0.2 mol / L Zr@Ni-TCPP solution. -1 The NaOH solution and 20.0 mL of ethanol solution were mixed and stirred until the system was fully mixed. The mixture was then slowly transferred to a reaction vessel and reacted at 180 °C for 12 h. After washing and drying, the composite product Co3Se4@Zr-Ni-TCPP photoelectrode material was obtained. By adjusting the mass of Co3Se4 to 0.2519 g, 0.3568 g, 0.4757 g, and 0.6117 g, and thus adjusting the loading ratio, 15% Co3Se4@Zr-Ni-TCPP, 20% Co3Se4@Zr-Ni-TCPP, 25% Co3Se4@Zr-Ni-TCPP, and 30% Co3Se4@Zr-Ni-TCPP were obtained.

[0042] Preparation of the working electrode: Hydrophobic carbon felt was cut into 2 cm × 3 cm pieces for later use. 5 mg of catalyst was dispersed in 0.5 mL of deionized water, 6 μL of naphthol solution was added, and after ultrasonic dispersion, it was uniformly deposited on the carbon felt (2 cm × 2 cm). After drying, a uniform catalyst thin layer was formed to obtain the Co3Se4@Zr-Ni-TCPP photocathode, denoted as Co3Se4@Zr-Ni-TCPP / CF.

[0043] Figure 1 In the image, a and b are SEM images of Co3Se4 and Zr-Ni-TCPP, respectively, showing typical nanoparticle morphology and ultrathin two-dimensional layered structure. c is the SEM image of Co3Se4@Zr-Ni-TCPP, indicating that Co3Se4 nanoparticles have been successfully loaded onto the Zr-Ni-TCPP surface.

[0044] like Figure 2 As shown, the XRD pattern of the composite material Co3Se4@Zr-Ni-TCPP not only exhibited characteristic diffraction peaks belonging to the Co3Se4 crystal phase, but also detected characteristic diffraction peaks consistent with those of the Zr-Ni-TCPP material. This result indicates that during the composite process, both Co3Se4 and Zr-Ni-TCPP components maintained their original crystal structures, without significant phase shifts or characteristic peak shifts due to inter-component interactions, thus confirming the successful fabrication of the photoelectrode material.

[0045] Figure 3The XPS full spectra of Co3Se4, Zr-Ni-TCPP, and Co3Se4@Zr-Ni-TCPP are shown. In the full spectrum of the Co3Se4@Zr-Ni-TCPP composite material, characteristic peaks of Zr, Ni, Co, Se, C, and N were detected simultaneously, indicating that Co3Se4 was successfully loaded onto the surface of the Zr-Ni-TCPP material.

[0046] Comparative Example 1

[0047] For comparison, a photocathode based on carbon paper was prepared under the same conditions.

[0048] Comparative Example 2

[0049] Under the same conditions, PDMS was coated on the surface of carbon felt, and then Co3Se4@Zr-Ni-TCPP was deposited to prepare photocathode.

[0050] Comparative Example: Preparation of 3Co3Se4@Ni-TCPP photoelectrode material and photocathode

[0051] Preparation of Co3Se4@Ni-TCPP: 12.0 mmol NaBH4, 4.0 mmol selenium powder, and 3.0 mmol Co(NO3)2·6H2O were sequentially ultrasonically dissolved in 20.0 mL deionized water and stirred until completely dissolved. Then, 1.79 mmol Ni-TCPP was added to the solution, followed by dropwise addition of 10.0 mL of 0.2 mol / L Ni-TCPP solution. -1 The NaOH solution and 20.0 mL of ethanol solution were mixed and stirred to ensure thorough mixing. The mixture was then slowly transferred to a reaction vessel and reacted at 160-190 °C for 10-15 h. After washing and drying, the composite product Co3Se4@Ni-TCPP was obtained.

[0052] Preparation of the working electrode: Hydrophobic carbon felt was cut into 2 cm × 3 cm pieces for later use. 5 mg of catalyst was dispersed in 0.5 mL of deionized water, 6 μL of naphthol solution was added, and after ultrasonic dispersion, it was uniformly deposited on the carbon felt (2 cm × 2 cm). After drying, a uniform catalyst thin layer was formed to obtain the Co3Se4@Ni-TCPP photocathode, denoted as Co3Se4@Ni-TCPP / CF.

[0053] Example 4 Co3Se 4、 Application of Zr-Ni-TCPP and Co3Se4@Zr-Ni-TCPP photocathodes in photoelectrocatalytic oxygen reduction for H2O2 production.

[0054] Using the photoelectrode obtained above as the working electrode, a Pt sheet as the counter electrode, and Ag / AgCl as the reference electrode, a three-electrode system is constructed. 20 mL 0.1 mol L -1 Na₂SO₄ solution was used as the electrolyte solution, with a concentration of 10 mol / L. -1 The pH of the solution was adjusted to 5 using HClO4. A 300W xenon lamp (λ > 420 nm) was used as the light source. The reaction system was controlled at approximately 15 °C using a water-circulating condenser. Before the catalytic reaction began, O2 was continuously introduced into the solution for 30 min in darkness. H2O2 was produced via photoelectrocatalysis under a bias voltage of -0.5V (vs. Ag / AgCl). A 0.5 mL sample was taken from the reactor every 20 min, and the concentration of H2O2 produced was determined using the potassium titanium oxalate method.

[0055] 1. LSV curves under different atmospheres

[0056] Figure 4 Linear sweep voltammetry (LSV) curves under different atmospheres are shown. Following the method in Example 4, O2 and N2 were continuously introduced into the solution for 30 min under dark conditions before the catalytic reaction began. It was observed that in the N2-saturated electrolyte solution, no significant current density response or characteristic reduction peak appeared for any sample, indicating that no significant oxygen reduction reaction occurred on the material surface under the N2 atmosphere. When O2 was introduced, the LSV curves of all samples showed obvious reduction characteristic peaks in the potential range of -0.4 to -0.5 V (vs. Ag / AgCl), indicating that the material has good oxygen reduction activity in this potential range and can efficiently catalyze the O2 reduction process. Compared with the two monomer materials Zr-Ni-TCPP and Co3Se4, the Co3Se4@Zr-Ni-TCPP composite material exhibited a stronger reduction characteristic peak and a significantly increased current density. Especially under light conditions, the catalytic advantage of this composite material was more prominent, and the reduction peak current was further enhanced. This is attributed to the synergistic effect between Co3Se4 and Zr-Ni-TCPP, which optimizes the electron transport path and increases the exposure of active sites, resulting in the strongest reduction peak and the highest current density.

[0057] 2. The effect of different materials on H2O2 production

[0058] like Figure 5 As shown, comparing the photoelectrocatalytic H2O2 production performance of different materials, the H2O2 yield of the Co3Se4@Zr-Ni-TCPP heterojunction was higher than that of both Zr-Ni-TCPP and Co3Se4 monomers. After 2.5 h of reaction, the H2O2 yield of Co3Se4@Zr-Ni-TCPP reached 11.4 mmol L. -1The yields were 7.5 times that of pure Co3Se4 and 1.5 times that of Zr-Ni-TCPP, respectively. These results indicate a significant synergistic effect between the two monomer materials, effectively enhancing the catalytic efficiency of the oxygen reduction reaction to generate hydrogen peroxide, thus confirming that the construction of heterojunctions can significantly improve H2O2 production.

[0059] 3. Effect of different Co3Se4 loadings on H2O2 production

[0060] like Figure 6 As shown, with the increase of Co3Se4 loading, the H2O2 production of Co3Se4@Zr-Ni-TCPP composite material also gradually increases. When the loading is 20%, the amount of H2O2 produced by photoelectrocatalysis is the largest. As the ZnSe loading further increases, the H2O2 production decreases instead.

[0061] 4. The effect of substrate material hydrophobicity on H2O2 production

[0062] The regulation of the electrode surface microenvironment for PEC 2e - The ORR route is crucial for H2O2 production. Traditional solid-liquid two-phase interface microenvironments severely restrict oxygen mass transfer, significantly inhibiting H2O2 production. Constructing a solid-liquid-gas three-phase interface microenvironment allows for the effective capture and enrichment of oxygen through hydrophobic channels, significantly increasing the local oxygen concentration at the interface. Furthermore, the three-phase interface microstructure optimizes proton transport channels and accessibility, ensuring a sufficient proton supply while guaranteeing oxygen supply. This promotes the two-electron oxygen reduction reaction (2e-O2). - ORR (Orbital-Reduction) is carried out efficiently, thereby significantly improving hydrogen peroxide yield and current efficiency. For example... Figure 7 As shown, a solid-liquid two-phase interface microenvironment electrode was constructed using hydrophilic carbon paper (hydrophobic angle = 68.7°) as the substrate, and a three-phase interface microenvironment electrode was constructed using hydrophobic carbon felt (hydrophobic angle = 138.5°) as the substrate. Figure 8 It can be seen that the yield of Co3Se4@Zr-Ni-TCPP / CF based on carbon felt is significantly better than that of Co3Se4@Zr-Ni-TCPP / CP based on carbon paper. Further coating of PDMS on the surface of carbon felt to improve its hydrophobicity (hydrophobic angle = 142.3°) to prepare electrodes, with the further improvement of its hydrophobicity, the H2O2 yield was further improved.

[0063] 5. Effect of different solution pH values ​​on H2O2 production

[0064] Figure 9The effects of different solution pH values ​​on the H2O2 production yield catalyzed by the material were compared. The pH of the solution was adjusted to 2, 5, 7, 10, and 13 using HClO4 and NaOH, respectively, to investigate the effect of pH on H2O2 production. As shown in the figure, Co3Se4@Zr-Ni-TCPP exhibited the highest H2O2 production under weakly acidic conditions at pH=5, effectively overcoming the limitation of traditional catalytic systems that can only efficiently produce H2O2 under strongly acidic conditions, achieving efficient photoelectrochemical oxygen reduction to H2O2 production across the entire pH range. In contrast, the undoped Zr Co3Se4@Ni-TCPP composite material showed a significant pH limitation, exhibiting optimal activity only under strongly acidic conditions at pH=2. With increasing pH, the H2O2 production decreased sharply, failing to adapt to a wide pH environment.

[0065] To further investigate the mechanism of photoelectrochemical H2O2 production using the Co3Se4@Zr-Ni-TCPP photoelectrode material, we conducted capture experiments, using p-benzoquinone (BQ), silver nitrate (AgNO3), isopropanol (IPA), and citric acid as •O2, respectively. - e - •OH and h + Capture agents, such as Figure 9 As shown, inert gas N2 and AgNO3 were introduced respectively to capture e. - Under these conditions, H2O2 formation was almost completely suppressed, demonstrating that H2O2 formation is highly dependent on the presence of O2, and that the oxygen reduction reaction is the key step in H2O2 formation. (Regarding the formation of Co3Se4@Zr-Ni-TCPP with O2...) − and e - After capture, a significant decrease in H2O2 production was observed, indicating that •O2 - and e − They play a crucial role in the ORR process to generate H2O2, and are the main active substances. The system is dominated by a highly selective two-step single-electron ORR reaction mechanism.

[0066] Based on the standard electrode potential for generating active particles (O2 / •O2) - (-0.33 eV vs. NHE)), combined with the capture experiment results and bandgap structure, S-mode conduction is considered to be the charge conduction mode of this heterojunction (e.g., Figure 11 ).

Claims

1. A method for preparing a photocathode with a gas-solid-liquid three-phase interface, characterized in that, Includes the following steps: Step 1: Preparation of Zr-Ni-TCPP: Ni(NO3)2·6H2O and PVP were dissolved in a mixed solvent to obtain solution A, and TCPP was dissolved in a mixed solvent to obtain solution B. Under vigorous stirring, solution B was slowly added dropwise to solution A, ultrasonically treated, transferred to an autoclave for hydrothermal reaction, and Ni-TCPP was obtained after washing and drying. Ni-TCPP and ZrOCl2·8H2O were mixed and stirred vigorously. Benzaldehyde was then added to the mixture and stirred until completely dissolved. The mixture was then stirred and reacted. After washing and drying, Zr-Ni-TCPP was obtained. Step 2: Preparation of Co3Se4@Zr-Ni-TCPP: NaBH4, selenium powder and Co(NO3)2·6H2O were ultrasonically dissolved in deionized water and stirred until completely dissolved. Zr-Ni-TCPP was then added, followed by dropwise addition of NaOH solution and ethanol solution. The mixture was stirred to ensure thorough mixing. The mixed solution was slowly transferred to a reaction vessel for hydrothermal reaction. After washing and drying, Co3Se4@Ni-TCPP was obtained.

2. The method for preparing a photocathode with a gas-solid-liquid three-phase interface according to claim 1, characterized in that, In step 1, the mixed solvent is obtained by mixing DMF and ethanol at a volume ratio of 3:

1.

3. The method for preparing a photocathode with a gas-solid-liquid three-phase interface according to claim 1, characterized in that, In step 1, the mass ratio is Ni(NO3)2·6H2O:PVP:TCPP = 15:10:

2.

4. The method for preparing a photocathode with a gas-solid-liquid three-phase interface according to claim 1, characterized in that, In step 1, the hydrothermal reaction is carried out at 80-85℃ for 22-24 hours, and the stirring reaction is carried out at 90-85℃ for 3-6 hours.

5. The method for preparing a photocathode with a gas-solid-liquid three-phase interface according to claim 1, characterized in that, In step 1, the mass ratio of Ni-TCPP:ZrOCl2·8H2O:benzaldehyde is 100:300:3.

3.

6. The method for preparing a photocathode with a gas-solid-liquid three-phase interface according to claim 1, characterized in that, In step 2, the molar ratio is NaBH4:selenium powder:Co(NO3)2·6H2O:Zr-Ni-TCPP=12:4:3:1.

52.

7. The method for preparing a photocathode with a gas-solid-liquid three-phase interface according to claim 1, characterized in that, In step 2, the hydrothermal reaction is carried out at 160-190℃ for 10-15 hours.

8. A photocathode having a gas-solid-liquid three-phase interface prepared according to the preparation method of any one of claims 1-7.

9. The application of the photocathode with a gas-solid-liquid three-phase interface as described in claim 8 in the photoelectrocatalytic oxygen reduction to prepare H2O2 over a wide pH range.

10. The application according to claim 9, characterized in that, The method is as follows: a photocathode with a gas-solid-liquid three-phase interface is used as the working electrode, a Pt sheet as the counter electrode, and Ag / AgCl as the reference electrode to form a three-electrode system. Na2SO4 solution is used as the electrolyte solution, and 10 mol L... -1 The pH of the solution was adjusted to 2-13 using HClO4. A xenon lamp was used as the light source, and the reaction system was controlled at 14-16℃. Before the catalytic reaction began, O2 was continuously introduced into the solution under dark conditions. H2O2 was produced by photoelectrocatalysis under a bias voltage of -0.5V vs. Ag / AgCl.

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