A method for preparing a surface-state modulated coupled plasmon-enhanced WO3 photoanode, the photoanode itself, and its applications.

Abstract

This invention provides a method for preparing a surface-state-modulated plasmon-enhanced WO3 photoanode, the photoanode itself, and its applications. The preparation method involves: fabricating a gold nanoarray on conductive glass to obtain Au-NAs / conductive glass; preparing a WO3 thin film to obtain an Au-NAs / WO3 photoanode; and subjecting the Au-NAs / WO3 photoanode to electrochemical reduction treatment to construct an amorphous layer on the WO3 surface, resulting in an Au-NAs / SA-WO3 photoanode. This invention embeds a gold nanoarray into the WO3 photoanode and constructs a surface amorphous layer containing a high density of gradient-distributed oxygen vacancies, synergistically coupling plasmon enhancement and surface-state modulation. This simultaneously optimizes light absorption, carrier dynamics, active site density, and product selectivity, significantly increasing the electrochemical active area of ​​the photoanode, improving carrier separation and transport efficiency and glycerol oxidation selectivity, and achieving highly efficient and selective conversion of glycerol to glyceric acid.

Description

Technical Field

[0001] This invention relates to the field of photoelectrocatalysis technology, and more specifically, to a method for preparing a surface state-regulated coupled plasmon-enhanced WO3 photoanode, the photoanode itself, and its applications. This photoanode can be applied to the selective oxidation of glycerol for the production of high-value-added chemicals and to the photoelectrocatalytic hydrogen production. Background Technology

[0002] Photoelectrocatalysis is a core technology for achieving efficient conversion of solar energy into chemical energy and supporting the construction of carbon neutrality and low-carbon energy systems. The photoanode, as a key component determining reaction efficiency, stability, and product selectivity, directly determines the energy conversion efficiency of the overall photoelectrochemical system through its intrinsic activity and interfacial kinetics. In recent years, composite photoelectrocatalytic systems, exemplified by the high-value-added biomass glycerol coupled with cathode hydrogen production, have developed rapidly, becoming an important direction for replacing traditional pure water oxidation and improving system economy and energy utilization. Biomass glycerol is a major byproduct generated during the large-scale global biodiesel production process, with annual production far exceeding industrial demand, reaching a surplus of millions of tons. Selectively oxidizing glycerol through photoelectrochemical processes to convert it into high-value-added fine chemicals such as glyceric acid (GLA), dihydroxyacetone (DHA), and glyceraldehyde (GLD), while simultaneously achieving efficient hydrogen production at the cathode, can simultaneously achieve the triple goals of biomass resource utilization, green hydrogen energy storage, and high-value chemical synthesis, combining environmental and economic benefits. This has become a research hotspot in the fields of renewable energy and catalytic materials.

[0003] Tungsten trioxide (WO3) possesses a suitable band structure, excellent stability in acidic environments, and high electron mobility (12 cm⁻¹). 2 ·V -1 ·s -1 WO3, with its favorable surface properties for glycerol molecule adsorption and C3 product desorption, is widely recognized as one of the most promising photoanode materials for the selective oxidation of glycerol in acidic systems. However, traditional pure-phase WO3 photoanodes have a wide intrinsic band gap, utilizing only the ultraviolet and a small portion of the visible light region, resulting in low utilization of the broad spectrum of sunlight and a limited number of photogenerated carriers, thus restricting photoelectric conversion efficiency. Furthermore, WO3 has limited intrinsic conductivity, leading to rapid recombination of photogenerated electron-hole pairs in the bulk phase. This results in short lifetimes and short migration distances, with a low proportion of carriers effectively reaching the surface to participate in the oxidation reaction, leading to low glycerol conversion efficiency and difficulty in increasing photocurrent density. Simultaneously, traditional WO3 films have a dense surface with few defects and a low density of active sites, resulting in a small electrochemically active area and limited contact area with the electrolyte and glycerol molecules. This leads to high interfacial charge transfer resistance and slow reaction kinetics.

[0004] Furthermore, glycerol molecules contain three hydroxyl groups, resulting in random adsorption patterns on traditional WO3 surfaces. This makes it impossible to achieve targeted adsorption and preferential activation of the terminal hydroxyl groups, leading to uncontrollable reaction pathways and a high likelihood of C-C bond breakage, generating low-value C2 and C1 byproducts. Consequently, the selectivity of target products, such as glyceric acid (GLA), is low. Simultaneously, the intact and highly symmetrical lattice of the WO3 surface makes it difficult to form defect sites and charge distribution patterns conducive to substrate-oriented adsorption. This hinders the precise control of the activation sequence of OH and CH bonds, making it difficult to thermodynamically and kinetically stabilize key intermediates and suppress side reactions. This series of interconnected technical challenges collectively constitutes the key bottleneck restricting the improvement of the photoelectrocatalytic performance of WO3 photoanodes.

[0005] Therefore, it is urgent to develop a WO3 photoanode that couples plasmon enhancement and precise surface state control to simultaneously achieve efficient carrier transport, specific adsorption and highly selective catalysis in order to solve the above problems.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for preparing a surface-state-modulated coupled plasmon-enhanced WO3 photoanode, the photoanode itself, and its applications. Through the synergistic design of an embedded gold nanoarray and a surface amorphous layer, the efficiency of carrier separation and transport and the selectivity of glycerol oxidation are improved, achieving highly efficient and selective conversion of glycerol into glyceric acid, while also exhibiting high activity and high stability.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: A method for preparing a surface-state modulated coupled plasmon-enhanced WO3 photoanode includes the following steps: S1. Gold nanoarrays are fabricated on conductive glass to obtain Au-NAs / conductive glass; S2. Prepare a WO3 thin film on the Au-NAs / conductive glass to obtain an Au-NAs / WO3 photoanode; S3. The Au-NAs / WO3 photoanode is subjected to electrochemical reduction treatment to construct an amorphous layer on the WO3 surface, thereby obtaining the Au-NAs / SA-WO3 photoanode.

[0009] Further, in step S1, a gold nanoarray is prepared on the conductive glass surface using ultraviolet lithography and deposition.

[0010] Further, in step S2, the WO3 thin film is prepared on the Au-NAs / conductive glass using a liquid phase method.

[0011] Furthermore, the thickness of the amorphous layer in step S3 is 0.8~2nm.

[0012] Further, the method for preparing the gold nanoarray in step S1 is as follows: first, a nanoarray with a planar structure is photolithographically formed on a conductive glass, and then Au is uniformly deposited on the nanoarray.

[0013] Further, the conductive glass in step S1 includes at least one of fluorine-doped tin oxide substrate, indium tin oxide substrate, and aluminum-doped zinc oxide substrate.

[0014] Furthermore, the gold nanoarray prepared in step S1 has a cubic phase crystal structure.

[0015] Furthermore, the nanostructures in the gold nanoarray prepared in step S1 are at least one of nanocylinders, nanocubes, and nanodisks.

[0016] Furthermore, the gold nanoarray prepared in step S1 has an array thickness of 30~80 nm.

[0017] Furthermore, the deposition process in step S1 employs at least one of vacuum evaporation, magnetron sputtering, and atomic layer deposition; preferably, vacuum evaporation is used to uniformly deposit Au onto the surface of the nanoarray.

[0018] Furthermore, the Au deposition thickness during step S1 is 30~80 nm.

[0019] Furthermore, the cross-sectional diameter or equivalent diameter of the nanostructure in the gold nanoarray prepared in step S1 is 5-20 μm.

[0020] Furthermore, the gold nanoarray prepared in step S1 is a nanodisc-shaped array with an array period of 10-40 μm.

[0021] Further, the method for preparing the Au-NAs / WO3 photoanode in step S2 includes: S2.1, loading a tungsten precursor solution onto the surface of the Au-NAs / conductive glass; S2.2, annealing at high temperature, and obtaining Au after cooling. NAs / WO3 photoanode.

[0022] Furthermore, the thickness of the WO3 film prepared in step S2 is 0.8~2.0 μm.

[0023] Furthermore, in the Au-NAs / WO3 photoanode prepared in step S2, WO3 has a monoclinic crystal structure.

[0024] Furthermore, in the Au-NAs / WO3 photoanode prepared in step S2, Au-NAs are uniformly embedded between the WO3 film and the conductive glass.

[0025] Further, in step S2.1, at least one of the following methods is used: drop coating, spray coating, hydrothermal coating, and spin coating, to load the tungsten precursor solution onto the surface of the gold nanoarray.

[0026] Furthermore, the tungsten source of the tungsten precursor solution in step S2.1 is ammonium metatungstate.

[0027] Furthermore, in step S2.2, the high-temperature annealing temperature is 400~500℃, and the heating rate is 2~5℃·min. -1 The heat treatment time is 0.5~2 hours, and Au is obtained after natural cooling. NAs / WO3 photoanode.

[0028] Furthermore, the amorphous layer described in step S3 contains oxygen vacancies distributed in a gradient.

[0029] Further, step S3, the electrochemical reduction process, is as follows: using the Au-NAs / WO3 photoanode as the working electrode, an electrochemical reduction process is carried out using a three-electrode system, the electrolyte is 0.1~0.2mol / L H2SO4 solution, the applied voltage is -0.7~-0.3 V vs. RHE, the electrochemical reduction time is 5~20 s, and an amorphous layer is induced to form on the WO3 surface.

[0030] Furthermore, the electrochemical reduction treatment in step S3 breaks the symmetry of the WO6 polyhedron, shifts the center of the d-band upward, and forms a defect dipole and redistributes the charge.

[0031] The photoanode prepared by the above method is an Au-NAs / SA-WO3 photoanode, which includes, from one side to the other, a conductive glass, a gold nanoarray constructed on the conductive glass, and a WO3 film. The gold nanoarray is uniformly embedded between the WO3 film and the conductive glass. An amorphous layer with a thickness of 0.8~2 nm is constructed on the surface of the WO3 film.

[0032] Furthermore, the Au-NAs / SA-WO3 photoanode exhibits a photocurrent density ≥4.5 mA·cm² under AM 1.5 G simulated sunlight and 1.23 V vs. RHE conditions. -2 Glyceric acid selectivity ≥70%, glyceric acid yield ≥520 mmol·m -2 ·h -1 The photocurrent retention rate is ≥80% after 5 hours of continuous illumination.

[0033] The photoanode prepared by the above method and its application are discussed in the selective oxidation of glycerol to high-value chemicals via photoelectrocatalysis and in the coupling of photoelectrocatalytic hydrogen production.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention relates to a method for preparing a surface-state-modulated coupled plasmon-enhanced WO3 photoanode, which embeds a gold nanoarray (Au) into the WO3 photoanode using a combination of ultraviolet lithography and electrochemical reduction strategies. Au was prepared by constructing a surface amorphous layer (SA) containing high-density oxygen vacancies and using NAs. NAs / SA WO3 photoanode. This invention uses Au. NAs / SA Embedded gold nanoarrays (Au) in WO3 photoanodes The photoanode (NAs) significantly improves the carrier separation and transport efficiency, achieving a photocurrent density of 4.8 mA·cm⁻¹ at a bias voltage of 1.23 V vs. RHE. -2 This invention Au NAs / SA In the WO3 photoanode, the surface amorphous layer (SA) with a high concentration of oxygen vacancies induces a redistribution of surface charge, enabling specific adsorption of glycerol terminal hydroxyl groups. This significantly improves the selectivity and conversion efficiency of glycerol oxidation, resulting in a glyceric acid yield ≥520 mmol·m⁻¹. -2 ·h -1 Glyceric acid selectivity ≥70%, glyceric acid yield ≥520 mmol·m -2 ·h -1 Photocurrent density ≥ 4.5 mA·cm -2 With a photocurrent retention rate of ≥80% after 5 hours of continuous illumination, it provides a novel and efficient photoanode material for the high-value utilization of biomass glycerol and the coupling of photoelectrocatalytic hydrogen production, and has broad application prospects in the fields of renewable energy conversion and fine chemical synthesis.

[0035] 2. This invention constructs an embedded gold nanoarray (Au-NAs), which utilizes the local surface plasmon resonance effect to broaden the light absorption range and enhance light absorption, while promoting the separation and transport of photogenerated carriers, significantly improving charge separation efficiency and photoelectrocatalytic reaction kinetics, and solving the problems of narrow light absorption range and easy recombination of carriers in traditional WO3.

[0036] 3. This invention constructs an amorphous layer with high density and gradient distribution of oxygen vacancies on the surface of WO3 through mild electrochemical reduction treatment, breaking the polyhedral symmetry of WO6, causing the d-band center to shift upward and form defect dipoles and charge redistribution, thereby achieving specific adsorption and directional activation of the terminal hydroxyl groups of glycerol, inhibiting C-C bond breaking and excessive oxidation from a thermodynamic and kinetic perspective, and significantly improving the selectivity of glyceric acid.

[0037] 4. This invention synergistically couples plasmon enhancement with surface state modulation, simultaneously optimizing light absorption, carrier dynamics, active site density, and product selectivity. The electrochemical active area of ​​the photoanode is significantly improved, and the surface charge transfer resistance is greatly reduced, achieving a simultaneous breakthrough in conversion efficiency and selectivity.

[0038] 5. The Au-NAs / SA-WO3 photoanode prepared in this invention can achieve a photocurrent density of 4.8 mA·cm⁻¹ under a bias voltage of 1.23 V vs. RHE. -2 The yield of glyceric acid can reach 621.9 mmol·m -2 ·h -1 It exhibits a selectivity of up to 73.7% and a photocurrent retention rate of up to 81.2% after 5 hours of continuous illumination. Its overall performance is superior to existing WO3-based photoanodes, combining high activity with high stability.

[0039] 6. The preparation process of this invention is mild, controllable, and highly reproducible. The ultraviolet lithography, solvent evaporation, and electrochemical reduction are all suitable for large-scale preparation. The prepared photoanode can realize the high-value conversion of biomass glycerol and the coupling of cathode hydrogen production, providing a new and efficient material for renewable energy conversion and green synthesis of fine chemicals, and has broad industrial application prospects. Attached Figure Description

[0040] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the process flow for preparing the Au-NAs / SA-WO3 photoanode in Embodiment 1 of the present invention; Figure 2 This is a high-resolution transmission electron microscope image of the Au-NAs / SA-WO3 photoanode prepared in Example 1 of this invention; Figure 3 The ultraviolet-visible-near-infrared absorption spectra of the Au-NAs / SA-WO3 photoanode prepared in Example 1 of the present invention, the WO3 photoanode prepared in Comparative Example 1, and the Au-NAs / WO3 photoanode prepared in Comparative Example 2. Figure 4 This is a diagram of the surface state density of the Au-NAs / SA-WO3 photoanode prepared in Example 1 of this invention; Figure 5 The surface defect dipole moment diagram of the Au-NAs / SA-WO3 photoanode prepared in Example 1 of this invention; Figure 6 The graph shows the photoelectrocatalytic selectivity of glycerol oxidation for the Au-NAs / SA-WO3 photoanode prepared in Example 1, the WO3 photoanode prepared in Comparative Example 1, and the Au-NAs / WO3 photoanode prepared in Comparative Example 2. Figure 7 The graph shows the yield of photoelectrocatalytic glycerol oxidation products of the Au-NAs / SA-WO3 photoanode prepared in Example 1, the WO3 photoanode prepared in Comparative Example 1, and the Au-NAs / WO3 photoanode prepared in Comparative Example 2. Figure 8 The results show the stability test results of the Au-NAs / SA-WO3 photoanode prepared in Example 1 of this invention and the WO3 photoanode prepared in Comparative Example 1. Figure 9 This diagram illustrates the structure of the Au-NAs / SA-WO3 photoanode of this invention, the surface state modulation coupling plasmon enhancement mechanism, and its application in photoelectrocatalytic reactions. Detailed Implementation

[0042] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0043] A method for preparing a surface-state modulated coupled plasmon-enhanced WO3 photoanode includes the following steps: S1. Prepare gold nanoarrays (Au-NAs) on conductive glass to obtain Au-NAs / conductive glass; S2. Prepare a WO3 thin film on the Au-NAs / conductive glass to obtain an Au-NAs / WO3 photoanode; S3. The Au-NAs / WO3 photoanode is subjected to electrochemical reduction treatment to construct an amorphous layer on the WO3 surface, thereby obtaining the Au-NAs / SA-WO3 photoanode.

[0044] In some embodiments, step S1 uses ultraviolet lithography and deposition to prepare gold nanoarrays (Au-NAs) on the conductive glass surface, preferably ultraviolet masking lithography.

[0045] In some embodiments, the method for preparing gold nanoarrays (Au-NAs) in step S1 is as follows: first, a nanoarray (NAs) with a planar structure is photolithographically formed on a conductive glass, and then Au is uniformly deposited on the nanoarray to obtain gold nanoarrays (Au-NAs).

[0046] Optionally, the deposition process employs at least one of vacuum evaporation, magnetron sputtering, and atomic layer deposition, with vacuum evaporation being preferred, to uniformly deposit Au onto the surface of the nanoarray.

[0047] In some implementations, the Au deposition thickness is 30~80nm, including but not limited to 30nm, 40nm, 50nm, 60nm, 70nm, and 80nm.

[0048] This invention constructs an embedded gold nanoarray using ultraviolet lithography and vacuum evaporation, utilizing the local surface plasmon resonance effect to broaden the light absorption range and enhance light absorption, while simultaneously promoting the separation and transport of photogenerated carriers, significantly improving charge separation efficiency and photoelectrocatalytic reaction kinetics, and solving the problems of narrow light absorption range and easy recombination of carriers in traditional WO3.

[0049] In some embodiments, the conductive glass in step S1 includes at least one of fluorine-doped tin oxide (FTO) substrate, indium tin oxide (ITO) substrate, and aluminum-doped zinc oxide (AZO) substrate.

[0050] In some embodiments, the gold nanoarrays (Au-NAs) prepared in step S1 have a cubic phase crystal structure.

[0051] In some embodiments, the nanostructures in the gold nanoarray (Au-NAs) prepared in step S1 are at least one of nanocylinders, nanocubes, and nanodisks.

[0052] In some embodiments, the cross-sectional diameter or equivalent diameter of the nanostructure in the gold nanoarray (Au-NAs) prepared in step S1 is 5-20 μm, including but not limited to 5 μm, 6 μm, 8 μm, 10 μm, 12 μm, 15 μm, 16 μm, 18 μm, and 20 μm.

[0053] In some embodiments, the gold nanoarrays (Au-NAs) prepared in step S1 have an array period of 10-40 μm (including but not limited to 10 μm, 20 μm, 30 μm, 40 μm) and an array thickness of 30-80 nm (including but not limited to 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm).

[0054] In some embodiments, the gold nanoarray prepared in step S1 is a nanodisc-shaped array with an array period of 10-40 μm.

[0055] In some embodiments, step S2 uses a liquid phase method to prepare a WO3 thin film on the Au-NAs / conductive glass.

[0056] In some embodiments, step S2 employs a solvent evaporation method combined with annealing to prepare a WO3 thin film on the Au-NAs / conductive glass.

[0057] In some embodiments, the WO3 film prepared in step S2 has a thickness of 0.8~2.0 μm (including but not limited to 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm) and is composed of dense small grains.

[0058] In some embodiments, the WO3 in the Au-NAs / WO3 photoanode prepared in step S2 has a monoclinic crystal structure.

[0059] In some embodiments, the Au-NAs in the Au-NAs / WO3 photoanode prepared in step S2 are uniformly embedded between the WO3 film and the conductive glass.

[0060] In some embodiments, the method for preparing the Au-NAs / WO3 photoanode in step S2 includes: S2.1 Loading the tungsten precursor solution onto the surface of the Au-NAs / conductive glass; S2.2, High-temperature annealing, followed by cooling to obtain Au. NAs / WO3 photoanode.

[0061] In some embodiments, step S2.1 employs at least one of the following methods: drop coating, spray coating, hydrothermal coating, and spin coating, to load the tungsten precursor solution onto the surface of the gold nanoarray.

[0062] In some embodiments, the tungsten source of the tungsten precursor solution in step S2.1 is ammonium metatungstate.

[0063] In some embodiments, the tungsten precursor solution includes ammonium metatungstate, citric acid, hydrochloric acid, and isopropanol. The percentage content of each component in the tungsten precursor solution is determined by conventional methods and will not be elaborated here.

[0064] In some embodiments, the high-temperature annealing temperature in step S2.2 is 400~500℃ (including but not limited to 400℃, 420℃, 450℃, 480℃, 500℃), and the heating rate is 2~5℃·min. -1 (including but not limited to 2℃·min) -1 3℃·min -1 4℃·min -1 5℃·min -1The heat treatment time is 0.5~2 h (including but not limited to 0.5h, 1h, 1.5h, 2h), and Au is obtained after natural cooling. NAs / WO3 photoanode.

[0065] In some embodiments, the thickness of the amorphous layer constructed on the WO3 surface in step S3 is 0.8~2nm (including but not limited to 0.8nm, 1nm, 1.2nm, 1.5nm, 1.6nm, 1.8nm, 2nm). This amorphous layer is an amorphous layer and exhibits a high density of oxygen vacancies compared to pure-phase WO3. The amorphous layer contains a gradient distribution of oxygen vacancies, and the oxygen vacancies (O...) in the surface amorphous layer... v The content of oxygen in the amorphous layer accounts for 15%-25% of the total oxygen content (the total oxygen content includes oxygen vacancies and lattice oxygen); the gradient distribution trend decreases from the surface to the bulk phase, with the highest concentration in the amorphous layer on the surface and a rapid decrease at the interface of the crystalline substrate.

[0066] In some embodiments, the electrochemical reduction process in step S3 is as follows: using the Au-NAs / WO3 photoanode as the working electrode, an electrochemical reduction process is performed using a three-electrode system. The electrolyte is a 0.1~0.2 mol / L (including but not limited to 0.1 mol / L, 0.12 mol / L, 0.15 mol / L, 0.18 mol / L, 0.2 mol / L) H2SO4 solution. The applied voltage is -0.7~-0.3 V vs. RHE (including but not limited to -0.3 V vs. RHE, -0.4 V vs. RHE, -0.5 V vs. RHE, -0.6 V vs. RHE, -0.7 V vs. RHE), and the electrochemical reduction time is 5~20 s (including but not limited to 5 s, 10 s, 15 s, 20 s), inducing the formation of an amorphous layer on the WO3 surface.

[0067] This invention utilizes Au Electrochemical reduction treatment using NAs / WO3 photoanodes constructs an amorphous layer and high-density oxygen vacancies on the surface, breaking the polyhedral symmetry of WO6, shifting the d-band center upwards, forming defect dipoles and redistributing charges, resulting in surface-state-regulated coupled plasmon-enhanced Au. NAs / SA WO3 photoanode.

[0068] The photoanode prepared by the above preparation method is an Au-NAs / SA-WO3 photoanode, which includes, from one side to the other, a conductive glass, a gold nanoarray (Au-NAs) constructed on the conductive glass, and a WO3 film. The gold nanoarray (Au-NAs) is uniformly embedded between the WO3 film and the conductive glass. An amorphous surface layer (SA) with a thickness of 0.8~2nm is constructed on the surface of the WO3 film.

[0069] In some embodiments, the Au-NAs / SA-WO3 photoanode is a surface-state modulated coupled plasmon-enhanced WO3 photoanode, which has excellent carrier dynamics and specific adsorption capacity for glycerol terminal hydroxyl groups.

[0070] In some embodiments, the Au-NAs / SA-WO3 photoanode exhibits a photocurrent density ≥4.5 mA·cm² under AM 1.5 G simulated sunlight and 1.23 V vs. RHE conditions. -2 Glyceric acid selectivity ≥70%, glyceric acid yield ≥520 mmol·m -2 ·h -1 The photocurrent retention rate is ≥80% after 5 hours of continuous illumination.

[0071] The photoanode prepared by the above preparation method or its application is used in the selective oxidation of glycerol to high-value chemicals by photoelectrocatalysis and in the coupling of photoelectrocatalytic hydrogen production.

[0072] Example 1 A method for preparing a surface-state modulated coupled plasmon-enhanced WO3 photoanode includes the following steps: 1. Fabrication of gold nanoarrays (Au-NAs): FTO conductive glass was sequentially ultrasonically cleaned with acetone, ethanol, and deionized water for 30 min each, and then dried with nitrogen. A planar nanoarray structure was lithographically patterned on the FTO glass surface using ultraviolet lithography. Au was then uniformly deposited onto the surface of the planar nanoarray structure using vacuum evaporation, with an Au deposition thickness of 50 nm. The resist was then removed. The resulting gold nanoarrays (Au-NAs) were nanodisc-shaped arrays with a cross-sectional diameter of 10 μm, thus fabricating a cubic Au-NAs / FTO substrate with an array period of 10 μm and an array thickness of 50 nm.

[0073] 2. Preparation of Au-NAs / WO3 photoanode: A tungsten precursor solution was drop-coated onto the surface of an Au-NAs / FTO substrate using a solvent evaporation method. The substrate was then annealed in a muffle furnace at 450 °C at a heating rate of 5 °C / min. -1 After holding at the temperature for 2 hours and then naturally cooling, an Au-NAs / WO3 photoanode is obtained, in which WO3 is a monoclinic phase, the WO3 film thickness is 1.0 μm, and Au-NAs are uniformly embedded between WO3 and the FTO substrate.

[0074] 3. Preparation of Au-NAs / SA-WO3 photoanode: Using the Au-NAs / WO3 photoanode as the working electrode, an electrochemical reduction treatment was performed using a three-electrode system. The electrolyte was 0.1 mol / L H2SO4 solution, the applied voltage was -0.568 V vs. RHE, and the electrochemical reduction time was 15 s. After treatment, an amorphous layer with a thickness of 1.6 nm and containing high density and gradient distribution of oxygen vacancies was formed on the WO3 surface, thus obtaining the Au-NAs / SA-WO3 photoanode.

[0075] Example 2 The difference between this embodiment and Embodiment 1 is that the cross-sectional diameter in step 1 is 10 μm. Everything else is the same as in Embodiment 1.

[0076] Example 3 The difference between this embodiment and Embodiment 1 is that in step 2, the heating rate is 3 °C·min. -1 The rest is the same as in Example 1.

[0077] Example 4 The difference between this embodiment and Embodiment 1 is that the electrochemical reduction time in step 3 is 10 s. Everything else is the same as in Embodiment 1.

[0078] Comparative Example 1 A conventional method for preparing WO3 differs from Example 1 in that: in Comparative Example 1, pure-phase WO3 photoanode material is directly prepared on an FTO substrate, omitting step 1 (preparation of Au-NAs) and step 3 (electrochemical reduction treatment). The rest is the same as in Example 1.

[0079] Comparative Example 2 A method for preparing Au-NAs / WO3, Comparative Example 2 differs from Example 1 in that: after completing steps 1 and 2 to prepare the Au-NAs / WO3 photoanode, Comparative Example 2 did not perform step 3, the electrochemical reduction treatment. The rest is the same as in Example 1.

[0080] Test case I. For example Figure 2 As shown, a high-resolution transmission electron microscope image of the Au-NAs / SA-WO3 photoanode prepared in Example 1 clearly shows lattice fringes with a plane spacing of 0.261 nm, corresponding to the (202) crystal plane of the monoclinic WO3 structure. Furthermore, an amorphous phase a-WO3 with a thickness of approximately 1.6 nm was observed on the WO3 surface.

[0081] II. Figure 3As shown, the ultraviolet-visible-near-infrared absorption spectrum of the Au-NAs / SA-WO3 photoanode prepared in Example 1 covers 300~700nm. Compared with pure WO3 in Comparative Example 1 (which only absorbs ≤450nm), the absorption of the Au-NAs / WO3 photoanode prepared in Comparative Example 2 is significantly lower than that of the Au-NAs / SA-WO3 photoanode. The light absorption of the Au-NAs / SA-WO3 photoanode prepared in Example 1 is significantly enhanced, and the light absorption range is greatly broadened.

[0082] III. Figure 4 The figure shows the density of states (DOS) diagram of the Au-NAs / SA-WO3 photoanode prepared in Example 1. As can be seen from the figure, the valence band (VB) is mainly composed of O 2p orbitals, while the conduction band (CB) is composed of W 4d orbitals. After electrochemical reduction, defect states dominated by oxygen vacancies appear in the band gap. Furthermore, oxygen vacancies and surface amorphous states disrupt the structural symmetry of the WO6 polyhedron, leading to an upward shift of the d-band center of W and significantly enhancing the dipole moments along the x, y, and z directions (e.g., ...). Figure 5 (As shown).

[0083] IV. Construction of a photoelectrochemical catalytic selective oxidation coupled hydrogen production system for glycerol: The photoelectrochemical performance of the Au-NAs / SA-WO3 photoanodes prepared in Examples 1-4, the WO3 photoanode prepared in Comparative Example 1, and the Au-NAs / WO3 photoanode prepared in Comparative Example 2 was characterized using a standard three-electrode potentiostatic system (photoelectrochemical performance data are shown in Table 1). The area of ​​the photoanode exposed to the electrolyte was fixed at 1 cm². 2 The electrolyte is an acidic system containing glycerol. The photoanode is illuminated from the front by a light source equipped with an AM 1.5 G simulated sunlight filter (100 mW·cm²). -2 The reactor system was evacuated, and a photoelectrocatalytic selective oxidation of glycerol coupled with hydrogen production was conducted in the vacuum reaction system. The generated hydrogen was analyzed by a gas chromatograph equipped with a thermal conductivity detector, and the products such as glyceric acid were quantitatively analyzed by high performance liquid chromatography.

[0084] Table 1. Photoelectrochemical performance data of photoanodes prepared in Examples 1-4 and Comparative Examples 1-2

[0085] As shown in Table 1, the Au-NAs / SA-WO3 photoanode of this invention exhibits a photocurrent density ≥4.5 mA·cm² under AM 1.5 G simulated sunlight and 1.23 V vs. RHE conditions. -2 Glyceric acid selectivity ≥70%, glyceric acid yield ≥520 mmol·m -2 ·h -1 The photocurrent retention rate is ≥80% after 5 hours of continuous illumination, exhibiting both high activity and high stability.

[0086] like Figure 6 As shown, the Au-NAs / SA-WO3 photoanode prepared in Example 1 exhibits a selectivity of 73.7% for glyceric acid under a bias voltage of 1.23 V vs. RHE. Figure 7 As shown, the yield of glyceric acid was 621.9 mmol·m³. -2 ·h -1 In addition, such as Figure 8 As shown, the Au-NAs / SA-WO3 photoanode prepared in Example 1 maintained a photocurrent retention rate of 81.2% after 5 hours of continuous illumination, indicating good stability.

[0087] In summary, this invention provides a method for preparing a surface-state-controlled, plasmon-coupled, enhanced WO3 photoanode, along with the photoanode itself and its applications. An embedded gold nanoarray is fabricated using ultraviolet lithography, and an Au-NAs / WO3 heterostructure is prepared by solvent evaporation and annealing. This is followed by electrochemical reduction to construct a surface amorphous layer (SA) containing high-density oxygen vacancies, resulting in the Au-NAs / SA-WO3 photoanode. The embedded gold nanoarray enables efficient carrier separation and transport, while the charge redistribution induced by the surface amorphous layer (SA) facilitates the specific adsorption of glycerol terminal hydroxyl groups. The Au-NAs / SA-WO3 photoanode material of this invention exhibits highly efficient carrier kinetics, excellent photoelectrocatalytic selective oxidation of glycerol to high-value chemicals, and coupled hydrogen production performance and stability. It provides a novel, highly efficient photoanode material for the high-value utilization of biomass glycerol and renewable energy conversion. The preparation process of the Au-NAs / SA-WO3 photoanode is simple and controllable, and it has broad application prospects in the fields of renewable energy conversion and fine chemical synthesis.

[0088] The upper and lower limits of the process parameters (such as temperature, time, concentration, etc.) and the range values ​​of the intervals can all achieve the present invention, and examples are not listed here. All aspects not described in detail in this invention can be covered using conventional technical knowledge in the field.

[0089] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a surface-state-controlled coupled plasmon-enhanced WO3 photoanode, characterized in that, Includes the following steps: S1. Gold nanoarrays are fabricated on conductive glass to obtain Au-NAs / conductive glass; S2. Prepare a WO3 thin film on the Au-NAs / conductive glass to obtain an Au-NAs / WO3 photoanode; S3. The Au-NAs / WO3 photoanode is subjected to electrochemical reduction treatment to construct an amorphous layer on the WO3 surface, thereby obtaining the Au-NAs / SA-WO3 photoanode.

2. The method for preparing a surface-state-controlled coupled plasmon-enhanced WO3 photoanode according to claim 1, characterized in that, It should include at least one of the following technical features: (1) In step S1, gold nanoarrays are prepared on the surface of the conductive glass using ultraviolet lithography and deposition. (2) In step S2, the WO3 thin film is prepared on the Au-NAs / conductive glass using a liquid phase method; (3) The thickness of the amorphous layer in step S3 is 0.8~2nm.

3. The method for preparing a surface-state modulated coupled plasmon-enhanced WO3 photoanode according to claim 2, characterized in that, It should include at least one of the following technical features: (1) The method for preparing the gold nanoarray in step S1 is as follows: firstly, a nanoarray with a planar structure is photolithographically formed on a conductive glass, and then Au is uniformly deposited on the nanoarray; (2) The conductive glass in step S1 includes at least one of fluorine-doped tin oxide substrate, indium tin oxide substrate, and aluminum-doped zinc oxide substrate; (3) The gold nanoarray prepared in step S1 has a cubic phase crystal structure; (4) The nanostructures in the gold nanoarray prepared in step S1 are at least one of nanocylinders, nanocubes, and nanodiscs; (5) The thickness of the gold nanoarray prepared in step S1 is 30~80nm.

4. The method for preparing a surface-state-controlled coupled plasmon-enhanced WO3 photoanode according to claim 3, characterized in that, It should include at least one of the following technical features: (1) The deposition process in step S1 adopts at least one of vacuum evaporation, magnetron sputtering, and atomic layer deposition; preferably, vacuum evaporation is used to uniformly deposit Au on the surface of the nanoarray. (2) The Au deposition thickness during step S1 is 30~80nm; (3) The cross-sectional diameter or equivalent diameter of the nanostructure in the gold nanoarray prepared in step S1 is 5-20 μm; (4) The gold nanoarray prepared in step S1 is a nanodisc array with an array period of 10-40 μm.

5. The method for preparing a surface-state-controlled coupled plasmon-enhanced WO3 photoanode according to claim 2, characterized in that, It should include at least one of the following technical features: （ 1) The method for preparing the Au-NAs / WO3 photoanode in step S2 includes: S2.1, loading a tungsten precursor solution onto the surface of the Au-NAs / conductive glass; S2.2, annealing at high temperature, and obtaining Au after cooling. NAs / WO3 photoanode; (2) The thickness of the WO3 film prepared in step S2 is 0.8~2.0 μm; (3) The WO3 in the Au-NAs / WO3 photoanode prepared in step S2 has a monoclinic crystal structure; (4) In the Au-NAs / WO3 photoanode prepared in step S2, Au-NAs are uniformly embedded between the WO3 film and the conductive glass.

6. The method for preparing a surface-state-controlled coupled plasmon-enhanced WO3 photoanode according to claim 5, characterized in that, It should include at least one of the following technical features: (1) Step S2.1 Use at least one of the following methods to load the tungsten precursor solution onto the surface of the gold nanoarray: drop coating, spray coating, hydrothermal coating, spin coating; (2) The tungsten source of the tungsten precursor solution mentioned in step S2.1 is ammonium metatungstate; (3) In step S2.2, the high-temperature annealing temperature is 400~500℃, and the heating rate is 2~5℃·min. -1 The heat treatment time is 0.5~2 hours, and Au is obtained after natural cooling. NAs / WO3 photoanode.

7. The method for preparing a surface-state-controlled coupled plasmon-enhanced WO3 photoanode according to claim 2, characterized in that, It should include at least one of the following technical features: (1) The amorphous layer described in step S3 contains oxygen vacancies distributed in a gradient; (2) Step S3 electrochemical reduction process is as follows: using the Au-NAs / WO3 photoanode as the working electrode, a three-electrode system is used for electrochemical reduction treatment. The electrolyte is 0.1~0.2mol / L H2SO4 solution, the applied voltage is -0.7~-0.3 V vs. RHE, the electrochemical reduction time is 5~20 s, and an amorphous layer is induced to form on the WO3 surface; (3) Step S3 electrochemical reduction treatment breaks the symmetry of WO6 polyhedron, shifts the center of d-band upward, and forms defect dipoles and redistributes charge.

8. The photoanode prepared by the preparation method according to any one of claims 1 to 7, characterized in that, The photoanode is an Au-NAs / SA-WO3 photoanode, which consists of a conductive glass, a gold nanoarray constructed on the conductive glass, and a WO3 film from one side to the other. The gold nanoarray is uniformly embedded between the WO3 film and the conductive glass. An amorphous layer with a thickness of 0.8~2 nm is constructed on the surface of the WO3 film.

9. The photoanode according to claim 9, characterized in that, The Au-NAs / SA-WO3 photoanode exhibits a photocurrent density ≥4.5 mA·cm² under AM 1.5 G simulated sunlight and 1.23 V vs. RHE conditions. -2 Glyceric acid selectivity ≥70%, glyceric acid yield ≥520 mmol·m -2 ·h -1 The photocurrent retention rate is ≥80% after 5 hours of continuous illumination.

10. The application of the photoanode prepared by the preparation method according to any one of claims 1 to 7, and the photoanode according to claim 8 or 9, characterized in that, Applications in the selective oxidation of glycerol to high-value chemicals via photoelectrocatalysis and in the coupling of photoelectrocatalytic hydrogen production.

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