Application of Bi2O2Se in photocatalytic nitrogen fixation reaction

Abstract

The application relates to application of Bi2O2Se in a photocatalytic nitrogen fixation reaction and belongs to the technical field of photocatalytic nitrogen reduction. The BOS catalyst with intrinsic weak hole oxidation capacity realizes efficient and stable photocatalytic ammonia synthesis without a sacrificial agent. The BOS has an optimized narrow band gap structure and a unique straddling energy band arrangement, the valence band position is shallow, the hole oxidation capacity is weak, the oxidation degradation of NH4 + Can be effectively inhibited, and the conduction band position is suitable, so that the thermodynamic driving force of nitrogen reduction is ensured. The catalyst has excellent light absorption capacity in a wide spectral range (extending to the near-infrared region), and the apparent quantum efficiency reaches 0.12% at a wavelength of 700 nm. The ammonia synthesis rate of the BOS without a sacrificial agent reaches 61 muM.h ‑1 -1, which is 8.3 times and 2.8 times that of carbon nitride and cadmium sulfide, and the catalyst maintains high activity in an air atmosphere, has excellent oxygen compatibility and cycle stability.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic nitrogen fixation technology, and specifically relates to the application of Bi2O2Se in photocatalytic nitrogen fixation reaction. Background Technology

[0002] Photocatalytic nitrogen reduction technology, as an environmentally friendly and energy-efficient disruptive alternative, holds promise for replacing the energy-intensive Haber-Bosch process and achieving ammonia synthesis under mild conditions. However, the extremely high bond dissociation energy of the N≡N triple bond (941 kJ / mol) remains a significant challenge. -1 This fundamentally limits the catalytic performance, making it difficult to reach industrial-scale applications.

[0003] Current research strategies primarily focus on optimizing photon capture and charge carrier dynamics. These methods have proven effective in traditional photocatalytic systems (such as photocatalytic water splitting and pollutant degradation), but their effectiveness has waned in nitrogen fixation applications due to the unique multi-electron transfer requirements and extremely high activation energy barrier of nitrogen reduction reactions. Even combining N≡N activation strategies with traditional carrier engineering has failed to achieve breakthrough efficiency improvements, indicating that our understanding of the catalytic mechanisms of nitrogenase-mimicking enzymes is still incomplete.

[0004] The inherent dual reactivity of photocatalytic systems presents unique mechanistic challenges. Semiconductor-mediated photocatalysis promotes both conduction band (CB)-mediated reduction and valence band (VB)-driven oxidation pathways through photogenerated electron-hole pairs. This redox duality makes it possible to obtain desired nitrogen reduction products (such as NH4). + Thermodynamically, NH4 is susceptible to re-oxidation via proton-coupled electron transfer (PCET) through VB holes. + The relatively unstable NH bond (bond energy ≈ 390 kJ / mol) -1 It is highly sensitive to oxidative fracture and readily forms nitrate / nitrite byproducts through Mars-van Krevelen type surface interactions.

[0005] Current mitigation strategies primarily employ sacrificial agents (such as methanol and triethanolamine) to preferentially scavenge VB holes, thereby kinetically inhibiting the oxidation pathway. However, this approach has three fundamental limitations: (1) excess donor molecules cause photon attenuation through Rayleigh scattering; (2) economic / environmental costs associated with the consumption of stoichiometric reagents; and (3) downstream purification complexity caused by donor-derived byproducts.

[0006] Therefore, there is an urgent need to develop a disruptive catalyst design framework that can simultaneously solve the problems of photon-to-exciton conversion, directional carrier transport, and targeted orbital hybridization with N2 molecules. By strategically controlling the performance band structure, catalysts with intrinsically weakened oxidation capabilities can be designed to fundamentally suppress the ammonium ion re-oxidation process. Summary of the Invention

[0007] To address the challenges in existing photocatalytic nitrogen fixation technologies, such as high activation energy barrier of N≡N triple bond, severe recombination of photogenerated carriers, and NH4+ ions... + The products are easily re-oxidized and the dependence on sacrificial agents leads to problems such as economic costs and environmental burden. This invention provides an application of Bi2O2Se in photocatalytic nitrogen fixation. The Bi2O2Se (BOS) is a novel semiconductor photocatalyst with intrinsically weakened oxidation ability. Through strategic performance band structure regulation, it can achieve efficient and stable photocatalytic nitrogen reduction reaction without the need for sacrificial agents.

[0008] This invention is achieved through the following technical solution: An application of Bi2O2Se in photocatalytic nitrogen fixation reaction, wherein Bi2O2Se acts as a photocatalyst, utilizing its inherent weak hole oxidation ability to catalyze the reduction of nitrogen to ammonia under sacrificial agent-free conditions.

[0009] Furthermore, the preparation method of Bi2O2Se includes the following steps: Bi₂O₃, Bi, and Se powders were mixed and then sealed in a vacuum-sealed quartz ampoule. The ampoule was heated to 573 K and held for 6 hours. Subsequently, it was heated to 773 K and held for 6 hours. After cooling to room temperature, the product was washed several times with ultrapure water and ethanol. Finally, it was dried at 333 K to obtain BOS powder.

[0010] Furthermore, the molar ratio of Bi₂O₃ to Bi is 1:1, and the molar ratio of Bi to Se powder is 1:1.5.

[0011] Furthermore, the Bi2O2Se has a layered stacked structure and exhibits a tetragonal crystal configuration. The interlayer spacings of BOS(110), BOS(103), and BOS(101) are 0.275 nm, 0.281 nm, and 0.370 nm, respectively.

[0012] Furthermore, the Bi₂O₂Se exhibits resistance to oxygen interference; the catalyst can maintain its photocatalytic nitrogen fixation activity even in an oxygen-containing atmosphere, and NH₄ + The yield showed no significant decrease compared to a nitrogen-purged environment.

[0013] Furthermore, for the vacuum energy level, the work function of the Bi2O2Se photocatalyst is 4.04 eV, the valence band edge position is 4.82 eV, and the conduction band edge position is 3.91 eV.

[0014] Furthermore, the Bi2O2Se possesses an optimized narrow bandgap structure and a straddle-type band arrangement, with a shallow valence band position and weak hole oxidation ability, which can effectively suppress NH4+. + Oxidative degradation.

[0015] Furthermore, the catalyst can be recycled.

[0016] Beneficial technical effects of the present invention: (1) This invention uses Bi2O2Se(BOS), which has intrinsic weak hole oxidation ability, as a catalyst to suppress the photogenerated holes from the source to the product NH4. + The oxidative consumption of ammonia enables efficient and stable accumulation of ammonia without the addition of any sacrificial agents.

[0017] (2) The Bi2O2Se photocatalyst of this invention achieves a sacrificial nitrogen fixation efficiency far exceeding that of traditional catalysts. In a pure water reaction system, the ammonia synthesis rate of BOS reaches 61µMh⁻¹, which is 8.3 times and 2.8 times higher than that of traditional photocatalysts such as carbon nitride (CN) and cadmium sulfide (CdS), respectively, demonstrating its great advantage in the intrinsic nitrogen fixation pathway.

[0018] (3) The Bi2O2Se photocatalyst exhibits considerable nitrogen fixation efficiency in both ambient air and pure nitrogen atmospheres. This characteristic eliminates the dependence on high-purity nitrogen, significantly reduces operating costs and equipment requirements, and has great potential for practical application.

[0019] (4) BOS has a wide-spectrum absorption characteristic, and its light response range extends to the near-infrared region. It can still maintain an apparent quantum efficiency of 0.12% at 700nm, which greatly improves the utilization rate of sunlight and breaks through the limitation of traditional catalysts that can only utilize visible light.

[0020] (5) The excellent performance of BOS stems from its intrinsic bulk properties without any surface modification. This not only simplifies the catalyst preparation process and reduces costs, but also ensures that its layered crystal structure is stable and its activity does not significantly decrease under long-term cycling tests (more than 20 times) and light irradiation, demonstrating excellent durability. Attached Figure Description

[0021] Figure 1 (a) X-ray diffraction pattern of BOS; (b)-(c) High-resolution transmission electron microscopy images of BOS; (d) Selected area electron diffraction pattern of BOS; (e) X-ray photoelectron spectra of Bi4f, (f) Se3d, and (g) O1s levels.

[0022] Figure 2 (a) Absorption spectrum of the entire solar spectrum; (b) Band gap; (ce) Ultraviolet photoelectron spectrum; (f) Schematic diagram of the band structure of BOS, CN and CdS.

[0023] Figure 3(a) Photocatalytic nitrogen fixation efficiency of the catalyst in a system containing 5% methanol; (b) Linear fitting of the methanol co-catalytic enhancement factor of the catalyst with methanol concentration; (c) Linear relationship between valence band position and the slope of the methanol concentration fitting; (d) Photocatalytic nitrogen fixation efficiency of the catalyst without sacrificial agent; (e) Electrochemical active surface area; (f) Electrochemical impedance spectroscopy; (g) Linear sweep voltammetry; (h) Photocurrent measurement; (i) Photocatalyst NH4 after normalization of light absorption capacity. + Generation amount.

[0024] Figure 4 (a) Photocatalytic oxidation of ammonia; (b) Photocatalytic nitrogen fixation efficiency of the catalyst under different atmospheres and without sacrificial agents; (c) Hole generation curves in the BOS photocatalytic system; (d) Photocatalytic nitrogen fixation rate of the catalyst and its Kc. air / KN2 ratio; (e) Valence band position and K air Linear fit between / KN2 ratio.

[0025] Figure 5 (a) Mechanism diagram of the effect of photocatalytic oxidation on nitrogen fixation efficiency; (b) Apparent quantum efficiency of the catalyst; (c) Isotope tracing experiment; (d) In-situ diffuse reflectance Fourier transform infrared spectrum of photocatalytic nitrogen fixation on BOS.

[0026] Figure 6 (a) Schematic diagram of the reaction pathway of N2 with different adsorption configurations on the BOS surface; (b) Calculation of Gibbs free energy change of the studied reaction pathway; (c) Long-term operational stability test of the BOS system and (d) Cyclic stability test; (e) X-ray diffraction patterns of fresh and used BOS. Detailed Implementation

[0027] Example 1: Synthesis of BOS Bi₂O₃ (1.36 mmol), Bi (1.36 mmol), and Se (2.04 mmol) powders were thoroughly mixed in stoichiometric ratio. The mixture was then sealed in a vacuum-sealed quartz ampoule. The ampoule was heated to 573 K and held at that temperature for 6 hours. Subsequently, it was heated to 773 K and held at that temperature for 6 hours. After cooling to room temperature, the product was washed several times with ultrapure water and ethanol. Finally, it was dried at 333 K to obtain BOS powder.

[0028] Comparative Example 1: Synthesis of graphitic carbon nitride (CN) 20 g of urea was placed in a crucible and calcined in a muffle furnace at 823 K for 4 hours at a heating rate of 5 K·min⁻¹. After cooling to room temperature, the resulting solid product was thoroughly washed with ultrapure water and ethanol to remove surface-adsorbed NH₃. Finally, the powder was dried at 333 K to obtain CN.

[0029] Comparative Example 2: Synthesis of CdS CdS was synthesized via a hydrothermal method, using CdCl2 and thiourea as the cadmium and sulfur sources, respectively. The procedure was as follows: 12 mmol of CdCl2 was dissolved in 80 mL of ultrapure water, followed by the addition of 12 mmol of thiourea. After stirring continuously for 1 hour, the mixture was transferred to a stainless steel autoclave lined with polytetrafluoroethylene (PTFE) and reacted at 433 K for 6 hours. After the reaction was complete, the system was cooled to room temperature, the precipitate was collected, thoroughly washed with ultrapure water and anhydrous ethanol, and dried at 333 K to obtain solid CdS product.

[0030] The material obtained in Example 1 was characterized as follows: XRD analysis confirmed the phase purity of BOS, which exhibited a clear tetragonal crystal configuration. Figure 1 a). The uniform distribution of constituent elements further confirms the successful synthesis and compositional homogeneity of BOS (Figure S3). HRTEM image ( Figure 1 (b, c) reveals that BOS exhibits a distinct layered stacked structure with interlayer spacings of 0.275 nm, 0.281 nm, and 0.370 nm, respectively. Selected area electron diffraction (SAED) patterns further confirm its crystallinity through clear (110), (103), and (101) diffraction rings. XPS analysis of the surface chemical state verifies the successful preparation of the BOS catalyst. Figure 1 e.g.

[0031] The electronic structure of the synthesized photocatalyst was systematically characterized through comprehensive photoelectric analysis. Compared with traditional visible light photocatalysts, BOS exhibits superior photon trapping ability over a wide spectral region and demonstrates significant infrared spectral reactivity, exceeding the absorption threshold of typical semiconductors. Figure 2 a). The BOS has an optimized narrow bandgap structure, which contrasts with a reference with a wider bandgap, a key feature for achieving efficient utilization of the solar spectrum. Figure 2 b).

[0032] Complementing these photoelectric properties, UPS (ultraviolet photoelectron spectroscopy) depicts the Fermi level alignment characteristics of materials relative to the vacuum level and the valence band edge potential—parameters that fundamentally control the interfacial charge transfer kinetics. The catalyst work function (Φ) is expressed by the relationship Φ = hυ + E. cutoff -E F , confirmed, where E cutoffThe experimentally measured secondary electron cutoff energy is given by EF, where EF is the Fermi level. UPS (ultraviolet photoelectron spectroscopy) measurements show that the work functions of BOS, CN, and CdS are 4.04, 3.40, and 3.75 eV (relative to the vacuum level), respectively. The corresponding valence band edge positions are determined to be 4.82, 5.82, and 5.48 eV (relative to the vacuum level). Through system band structure analysis, based on their respective band gap parameters, the minimum conduction band values ​​of BOS, CN, and CdS are derived to be 3.91, 3.05, and 3.44 eV (relative to the vacuum level), respectively. Figure 2 ce). Band edge diagram ( Figure 2 f) demonstrates the unique straddle band structure of BOS, which is thermodynamically favorable for the generation of photogenerated carriers and matches the redox potential required for nitrogen activation.

[0033] Ammonia Synthesis Determination

[0034] The catalytic reaction system was prepared by dispersing 20 mg of catalyst in 50 mL of ultrapure water containing a specific amount of methanol (if applicable) under a continuously purged atmosphere of N2 (or air) (flow rate 20 mL / min). A 30-minute dark reaction with stirring was first performed to establish adsorption-desorption equilibrium, followed by initiation of the photocatalytic reaction using a 300 W xenon lamp equipped with an AM 1.5G filter. Periodically, 2 mL of the reaction solution was taken, centrifuged, and the nitrogen-containing species (NH4+) were analyzed by ion chromatography. + NO3 - NO2 - Quantitative analysis was performed.

[0035] The formula for calculating the methanol co-catalytic enhancement factor (MECF) is as follows: Enhancer

[0036] in, k methanol This indicates the amount of NH4 in the reaction system when methanol is used as a sacrificial agent. + The generation rate, k water This indicates the amount of NH4 in the reaction system when no sacrificial agent is used. + The generation rate.

[0037] The photocatalytic nitrogen fixation performance was systematically evaluated using methanol as a sacrificial agent under full-spectrum irradiation. Although BOS exhibited superior broadband photon absorption, its catalytic performance was statistically comparable to that of conventional visible-light-active catalysts (carbon nitride and CdS) under standardized evaluation conditions. Figure 3a). This phenomenon is explained by band structure analysis, which shows that the relatively low conduction band minimum of BOS, compared to CN and CdS, imposes thermodynamic limitations on the electron-mediated reduction pathway.

[0038] A methanol co-catalytic enhancement factor (MECF) was established as a quantitative descriptor to evaluate the role of methanol in the photocatalytic ammonia synthesis of different catalytic systems. Figure 3 b shows that CdS and CN have steep slopes (0.21 and 0.41, respectively) in the methanol enhancement plot. Methanol concentration-dependent activity curves ( Figure 3 c) shows a linear correlation, with its proportionality coefficient positively correlated with the maximum valence band of the catalyst, indicating that hole-driven oxidation kinetics dominate the entire nitrogen activation process. In particular, materials with higher valence band positions are more dependent on sacrificial agent concentration, highlighting the crucial role of hole scavenging efficiency in controlling the thermodynamics of photocatalytic nitrogen fixation.

[0039] To verify the mechanism hypothesis, a rigorous evaluation was conducted on a sacrificial agent-free photocatalytic nitrogen fixation system. Figure 3 d). BOS exhibited unprecedented nitrogen activation efficiency, with a catalytic rate reaching 61 µM h⁻¹, exceeding that of conventional photocatalysts CN and CdS by 8.3 times and 2.8 times, respectively. Comprehensive characterization, including ECSA, EIS, LSV, and photocurrent measurements, was performed. Figure 3 The results (eh) show that CdS and CN exhibit significantly higher photocurrent and LSV current density than BOS. From a conventional perspective, this implies superior photogenerated carrier separation and migration efficiency. However, their actual photocatalytic ammonia yield in pure water is very low ( Figure 3 d). This phenomenon indicates that high carrier mobility is not the only key factor determining nitrogen fixation efficiency under sacrificial agent-free conditions. Although BOS has weaker carrier mobility, its nitrogen fixation performance is significantly better than that of traditional catalysts, revealing that there may be new limiting factors in the photocatalytic nitrogen fixation mechanism that are more critical than traditional performance indicators.

[0040] Normalized analysis of solar spectral energy capture efficiency further confirms the superior performance of BOS, particularly in the conversion of solar energy to NH4. + The conversion efficiency was 3.2 times and 1.5 times higher than that of CN and CdS, respectively. Figure 3 i). Conversely, BOS exhibits the lowest photoelectrochemical response (meaning poorer carrier transport) but the highest N2 fixation efficiency and the lowest methanol dependence. This confirms that BOS operates through a thermodynamically safe mechanism, namely, its shallow valence band position weakens the oxidation capacity of holes, prevents product degradation, and allows for efficient ammonia accumulation even under slower carrier kinetics.

[0041] ammonia oxidation experiment

[0042] The photocatalytic reaction system involves uniformly dispersing 20 mg of catalyst in 50 mL of 300 μM NH4. + The reaction mixture was prepared in an aqueous solution under continuous magnetic stirring. Solar irradiance simulation was achieved using a 300 W xenon arc lamp with an AM 1.5G filter to mimic ground-based solar irradiance conditions. Time-dependent monitoring of the reaction process involved periodically extracting 2 mL of the reaction solution at predetermined time points, followed immediately by filtration through a 0.22 μm filtration membrane to remove dispersed catalyst, and determining the NH4+ content in the filtrate by ion chromatography. + The concentration.

[0043] To further elucidate the relationship between the catalyst's oxidation properties and photocatalytic nitrogen fixation, the kinetics of ammonium ion oxidation were systematically studied. BOS exhibited limited oxidation efficiency (14.5% conversion of 300 μmol / L ammonium ions after 240 minutes of irradiation), in stark contrast to CN and CdS, which showed significantly enhanced ammonium oxidation. Figure 4 a). The excellent oxidation performance of traditional catalysts is accompanied by the simultaneous generation of nitrogen oxide species (NO⁻ and NO₂⁻). Whether using atmospheric air or pure nitrogen as the molecular nitrogen source, BOS exhibits comparable photocatalytic nitrogen fixation efficiency, revealing its inherent resistance to oxygen interference. Figure 4 b). In stark contrast, the conventional catalyst (CN / CdS) exhibits significant yield decay under aerobic conditions, particularly in the presence of NH4 in the air system. + The yield was significantly suppressed relative to a nitrogen-purged environment. Furthermore, Mn(II) probe analysis clearly confirmed the weakened oxidation potential and suppressed hole concentration within the BOS system. Figure 4 c). This means that in catalysts with higher valence band positions, oxygen-derived oxide species generated via hole-mediated oxidation pathways can actively degrade NH4. + Intermediate. Observed K air The negative correlation between the / KN2 ratio and the catalyst valence band potential confirms that excessive hole oxidation capacity will competitively quench active nitrogen species, adversely affecting nitrogen fixation efficiency. Figure 4 d, e).

[0044] BOS's superior photocatalytic nitrogen fixation performance stems fundamentally from its weakened intrinsic oxidation capability, enabling the catalyst to achieve robust catalytic function in a pure nitrogen environment without any sacrificial agents. Figure 5 a). This photocatalytic system exhibits excellent nitrogen activation performance over a wide spectral range, while maintaining a considerable quantum yield under near-infrared light irradiation (a). Figure 5(b) Furthermore, the low sensitivity to near-infrared wavelength removal highlights BOS's broad spectral response, distinguishing it from traditional visible-light-limited catalysts. This performance establishes its competitive advantage compared to current high-performance photocatalysts.

[0045] use 15 An N2-labeled isotope verification experiment confirmed the photogeneration of NH4. + The source of nitrogen. The reaction system was thoroughly purged with argon and strictly sealed to ensure that the reaction products were entirely derived from the supplied substrate. Spectroscopic analysis ( Figure 5 c) Display, in only using 15 The N2 system exhibited obvious 15 NH4 + Bimodal splitting mode, while using atmospheric conditions 14 At N2, characteristic features were observed. 14 NH4 + The triple peak signal confirms that the nitrogen products originate entirely from molecular nitrogen activation rather than external nitrogen contamination.

[0046] The key surface intermediate was revealed by DRIFTS (in-situ diffuse reflectance Fourier transform infrared spectroscopy): corresponding to the N-H2 bending vibration (1560 cm⁻¹). -1 NHN stretching vibration (1435 cm) -1 ) and NH4 + Deformation vibration (1260 cm) -1 The characteristic vibrational modes of the reaction increase over time, providing direct spectroscopic evidence for a continuous nitrogen activation-hydrogenation reaction pathway. Figure 5 d).

[0047] To further investigate the nitrogen activation mechanism, the Gibbs free energy of nitrogen reduction on the BOS surface was calculated, and the two configurations of "terminal adsorption" (vertical) and "lateral adsorption" (horizontal) were compared. Figure 6 (a and 6b). The terminal adsorption pathway exhibits significant bottlenecks: the association pathway (red) faces a severe thermodynamic energy barrier during the NH3 desorption stage (ΔG jumps from -2.71 to +0.49 eV), suggesting that the product may passivate the active site; while the dissociation pathway (light cyan) falls into a deep thermodynamic trap (-4.45 eV) when forming the ∗N intermediate, requiring an extremely high kinetic energy barrier of 2.30 eV to overcome for subsequent hydrogenation, which is difficult to achieve under mild conditions. In stark contrast, the lateral adsorption pathway (blue) exhibits a smoother potential surface and milder energy fluctuations throughout the reaction process. Its significantly lower overpotential and easy desorption characteristics together indicate that the lateral configuration is a more energy-efficient catalytic cycle pathway.

[0048] To investigate the catalytic stability of the BOS system, systematic long-term operation and cyclic testing were conducted. For example... Figure 6 As shown in c and 6d, the catalyst exhibits negligible activity decay over multiple cycles, demonstrating excellent photostability. Furthermore, post-catalytic XRD analysis reveals no significant phase transition compared to the original material, confirming the integrity of the BOS structure. Figure 6 e).

Claims

1. An application of Bi₂O₂Se in photocatalytic nitrogen fixation reaction, characterized in that: The Bi2O2Se is used as a photocatalyst, which utilizes its inherent weak hole oxidation ability to catalyze the reduction of nitrogen to ammonia under sacrificial agent-free conditions.

2. The application of Bi₂O₂Se in photocatalytic nitrogen fixation according to claim 1, characterized in that: The preparation method of Bi2O2Se includes the following steps: Bi₂O₃, Bi, and Se powders were mixed and then sealed in a vacuum-sealed quartz ampoule. The ampoule was heated to 573 K and held for 6 hours. Subsequently, it was heated to 773 K and held for 6 hours. After cooling to room temperature, the product was washed several times with ultrapure water and ethanol. Finally, it was dried at 333 K to obtain BOS powder.

3. The application of Bi₂O₂Se in photocatalytic nitrogen fixation reaction according to claim 2, characterized in that: The molar ratio of Bi₂O₃ to Bi is 1:1, and the molar ratio of Bi to Se powder is 1:1.

5.

4. The application of Bi₂O₂Se in photocatalytic nitrogen fixation reaction according to claim 1, characterized in that: The Bi2O2Se has a layered stacked structure and exhibits a tetragonal crystal configuration. The interlayer spacings of BOS(110), BOS(103), and BOS(101) are 0.275 nm, 0.281 nm, and 0.370 nm, respectively.

5. The application of Bi₂O₂Se in photocatalytic nitrogen fixation reaction according to claim 1, characterized in that: The Bi₂O₂Se exhibits resistance to oxygen interference; the catalyst can maintain its photocatalytic nitrogen fixation activity even in an oxygen-containing atmosphere, and NH₄ + The yield showed no significant decrease compared to a nitrogen-purged environment.

6. The application of Bi₂O₂Se in photocatalytic nitrogen fixation reaction according to claim 1, characterized in that: For the vacuum energy level, the work function of the Bi2O2Se photocatalyst is 4.04 eV, the valence band edge position is 4.82 eV, and the conduction band edge position is 3.91 eV.

7. The application of Bi₂O₂Se in photocatalytic nitrogen fixation according to claim 1, characterized in that: The Bi₂O₂Se possesses an optimized narrow bandgap structure and a straddle band arrangement, with a shallow valence band position and weak hole oxidation ability, which can effectively suppress NH₄⁺. + Oxidative degradation.

8. The application of Bi₂O₂Se in photocatalytic nitrogen fixation reaction according to claim 1, characterized in that: The catalyst can be recycled.

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