I-doped modified Cu2O composite photocatalytic nitrogen fixation material as well as preparation method and application thereof

Abstract

The invention relates to the field of photoelectric energy materials, in particular to an I-doped modified Cu2O composite photocatalytic nitrogen fixation material as well as a preparation method and application thereof.The method comprises the following steps: uniformly mixing a copper acetate solution, a NaOH solution and a glucose solution to obtain a first mixed solution; then, polyvinylpyrrolidone is added into the first mixed solution, heating reaction is carried out, and a reactant S0 is obtained; and finally, adding KI into the reactant S0, and carrying out hydrothermal reaction to obtain the composite photocatalytic nitrogen fixation material. Polyvinylpyrrolidone is used as a surfactant, agglomeration of Cu2O nanoparticles can be inhibited through a steric hindrance effect, and the service life of carriers is prolonged; by doping I, the N2 adsorption energy barrier is reduced, the transfer of photo-induced electrons from a Cu2O conduction band to N2 molecules is accelerated, and electron-hole recombination is inhibited, so that the photocatalytic activity and stability are improved, and the problems of low catalytic activity and poor stability when Cu2O is used as a catalyst for synthesizing ammonia through light nitrogen fixation are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric energy materials, and in particular to a composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O. Background Art

[0002] Nitrogen is a core component of life and a key raw material for agricultural fertilizers and chemical products. Traditional industrial nitrogen fixation relies on the Haber-Bosch process, which requires high temperatures (300°C to 500°C) and high pressures (15 to 30 MPa). This process consumes 1% to 2% of global energy consumption and produces 3% of global carbon dioxide emissions, leading to increasingly prominent energy and carbon emissions issues. Against this backdrop, photocatalytic nitrogen fixation, powered by solar energy, converts nitrogen (N2) to ammonia (NH3) at ambient temperature and pressure. With its advantages of low energy consumption, environmental friendliness, and mild reaction conditions, it is considered a revolutionary solution for "green nitrogen fixation."

[0003] Cuprous oxide (Cu2O), a typical narrow-bandgap semiconductor (Eg≈2.0-2.2 eV), exhibits excellent absorption in the visible light range, allowing it to be effectively excited by visible light, leading to photocatalytic reactions. Due to its unique electronic structure, low cost, and ease of preparation, Cu2O has become a research hotspot in the field of photocatalytic nitrogen fixation. Furthermore, Cu2O offers advantages such as non-toxicity, ease of preparation, a wide range of raw materials, low cost, and controllable morphology and size, further enhancing its competitiveness in various applications. Photocatalytic nitrogen fixation is a key application area for Cu2O, as it can fully utilize solar energy to synthesize ammonia through photocatalytic nitrogen fixation. The photocatalytic nitrogen fixation process can be divided into three stages: light absorption, charge carrier separation, and surface reaction. In the light absorption phase, Cu2O absorbs photons with energies ≥2.0 eV, causing valence-band electrons to transition to the conduction band, forming electron-hole pairs. In the carrier separation phase, photogenerated electrons and holes must rapidly separate and migrate to active sites on the catalyst surface. In the surface reaction phase, N2 molecules adsorb at defect sites (such as oxygen and copper vacancies), weakening the N≡N bond through an electronic feedback mechanism. Subsequently, N2 molecules are gradually hydrogenated to NH3 under the action of photogenerated electrons and H+. Carrier dynamics and surface reaction kinetics are key factors in determining the efficiency of photocatalytic nitrogen fixation. Because the recombination time of photogenerated carriers in Cu2O is only picoseconds, while surface reactions require milliseconds, most carriers remain unaffected, resulting in a high probability of recombination between photogenerated electrons and hole pairs. Furthermore, the low adsorption energy of N2 on the Cu2O surface and the multi-step high energy barrier in the hydrogenation pathway further limit the reaction rate, leading to low photocatalytic activity and poor stability. Summary of the Invention

[0004] In view of the problems in the prior art of using Cu2O as a catalyst for photo-nitrogen fixation and ammonia synthesis, such as low catalytic activity and poor stability due to the high probability of recombination of photogenerated electron-hole pairs and low carrier concentration in Cu2O, the present invention provides a composite photocatalytic nitrogen fixation material of I-doped modified Cu2O, a preparation method and application thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for preparing a composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O, comprising: Evenly mixing the copper acetate solution, the NaOH solution and the glucose solution to obtain a first mixed solution; Adding polyvinyl pyrrolidone to the first mixed solution and heating for reaction to obtain a reactant S0; KI is added to the reactant S0 and a hydrothermal reaction is carried out to obtain a composite photocatalytic nitrogen fixation material.

[0006] Optionally, the concentration of the copper acetate solution is 0.15-0.25 g / mL.

[0007] Optionally, the concentration of the NaOH solution is 0.7-0.9 mol / L.

[0008] Optionally, the concentration of the glucose solution is 1 to 1.5 mol / L.

[0009] Optionally, the volume ratio of the copper acetate solution, the NaOH solution and the glucose solution is 3:1:1.

[0010] Optionally, the concentration of polyvinyl pyrrolidone after adding polyvinyl pyrrolidone to the first mixed solution is 0.01 to 0.04 g / mL.

[0011] Optionally, the heating reaction condition is 80° C. to 100° C., and the reaction time is 10 to 18 hours.

[0012] Optionally, after adding KI to the reactant S0, the concentration of KI is 0.0002-0.0004 g / mL, and the hydrothermal reaction condition is 120° C.-140° C.

[0013] A composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O is prepared using the above-mentioned preparation method.

[0014] The application of the composite photocatalytic nitrogen fixation material of I-doped modified Cu2O in photocatalytic nitrogen fixation as mentioned above.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing a composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O. The method comprises the following steps: uniformly mixing a copper acetate solution, a NaOH solution, and a glucose solution to obtain a first mixed solution; then, adding polyvinyl pyrrolidone to the first mixed solution, heating the mixture for reaction, and obtaining a reactant S0; finally, adding KI to the reactant S0 and performing a hydrothermal reaction to obtain a composite photocatalytic nitrogen-fixing material. Polyvinyl pyrrolidone, as a surfactant, can inhibit the aggregation of Cu2O nanoparticles through a steric hindrance effect. At the same time, its polar groups (such as lactam rings) form chemical bonds with the Cu2O surface, reducing the surface defect state density. Since defect states are the main centers for carrier recombination, the reduction of defect states can effectively extend the carrier lifetime. Glucose not only acts as a reducing agent to reduce Cu2O nanoparticles, but also forms a bond with the Cu2O surface to reduce the surface defect state density. 2+ Reduction to Cu + (avoiding the formation of CuO impurity phase), its aldehyde group can also combine with the oxygen vacancies on the Cu2O surface to form a stable N2H intermediate adsorption site; KI releases I⁻ ions under high temperature and high pressure, and combines with the uncoordinated Cu on the Cu2O surface. + The Cu-I bond can reduce the N2 adsorption energy barrier and serve as an electron transfer channel to accelerate the transfer of photogenerated electrons from the Cu2O conduction band to the N2 molecules, inhibiting electron-hole recombination, thereby improving the photocatalytic activity and stability.

[0016] The concentration of the copper acetate solution is 0.15-0.25 g / mL; the concentration of the NaOH solution is 0.7-0.9 mol / L; and the concentration of the glucose solution is 1-1.5 mol / L. The volume ratio of the copper acetate solution, NaOH solution, and glucose solution is 3:1:1. By regulating the concentrations and mixing amounts of these reactants, the generation rate of Cu2O crystal nuclei can be controlled, the nanostructure can be optimized, and the effects of side reactions on the product properties can be avoided. This achieves synergistic optimization of the Cu2O nanostructure, I doping level, and surface modification, further improving the efficiency and stability of the composite photocatalytic nitrogen fixation material.

[0017] The application provides a composite photocatalytic nitrogen fixation material of I-doped modified Cu2O, which is prepared by using the preparation method, and through detection, the valence band (VB) of the composite photocatalytic nitrogen fixation material of I-doped modified Cu2O is 1.84 eV, the conduction band (CB) is-0.21 eV, the equilibrium potential of N2 reduction to NH3 is-0.092 V vs. NHE under standard conditions (pH value=7), in actual reactions, an activation energy barrier needs to be overcome, and generally, a more negative potential is needed to realize efficient conversion, the composite photocatalytic nitrogen fixation material of I-doped modified Cu2O can provide a stronger reduction driving force in photocatalytic nitrogen fixation, improve the ammonia production rate, realize comprehensive optimization of N2 reduction thermodynamics, carrier separation kinetics, surface reaction activity and material stability, and provide a key band engineering strategy for efficient and stable photocatalytic nitrogen fixation material design.

[0018] The composite photocatalytic nitrogen fixation material of I-doped modified Cu2O is applied to photocatalytic nitrogen fixation. Since the composite photocatalytic nitrogen fixation material of I-doped modified Cu2O has a wider light absorption range, a low carrier recombination probability, good stability and recyclability, has better light utilization, better redox capacity and a lower energy barrier in photocatalytic nitrogen fixation, provides a feasible scheme for replacing the industrial Haber-Bosch method (high temperature and high pressure, high energy consumption), and promotes the development of efficient and stable photocatalytic nitrogen fixation. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a preparation method flowchart of the composite photocatalytic nitrogen fixation material of I-doped modified Cu2O.

[0020] Figure 2 It is an XRD graph of the composite photocatalytic nitrogen fixation material of I-doped modified Cu2O prepared in example 1, example 2 and example 6 of the application.

[0021] Figure 3 It is an XRD spectrum of the composite photocatalytic nitrogen fixation material of I-doped modified Cu2O prepared in example 1 of the application.

[0022] Figure 4 It is an XRD spectrum of the composite photocatalytic nitrogen fixation material of I-doped modified Cu2O prepared in example 1 of the application after reaction for 10h, 14h and 18h.

[0023] Figure 5 It is an XRD spectrum of the composite photocatalytic nitrogen fixation material of I-doped modified Cu2O prepared by adding different amounts of PVP.

[0024] Figure 6XRD patterns of the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O prepared in Example 2 of the present invention under the first mixed liquid reaction conditions of 80°C, 90°C and 100°C.

[0025] Figure 7 This is the XPS graph of the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O prepared in Example 1 of the present invention, wherein a is the full spectrum, b is the Cu 2p high-resolution spectrum, c is the O 1s high-resolution spectrum, and d is the I 3d high-resolution spectrum.

[0026] Figure 8 These are SEM images of the composite photocatalytic nitrogen-fixing materials of I-doped modified Cu2O prepared in Examples 1, 2, and 6 of the present invention, wherein a is the SEM image of S0 in Example 1, b is the SEM image of S1 in Example 2, c is the SEM image of S2 in Example 1, and d is the SEM image of S3 in Example 6.

[0027] Figure 9 This is the EDAX spectrum analysis diagram of the composite photocatalytic nitrogen fixation material of I-doped modified Cu2O prepared in Examples 1, 2 and 6 of the present invention. Figure 10 These are BET data analysis graphs of the composite photocatalytic nitrogen-fixing materials of I-doped modified Cu2O prepared in Examples 1, 2 and 6 of the present invention, wherein a is the BET data analysis graph of the prepared reactant S0, b is the BET data analysis graph of the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O prepared in Example 2, c is the BET data analysis graph of the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O prepared in Example 1, and d is the BET data analysis graph of the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O prepared in Example 6.

[0028] Figure 11 αhv-hv curve diagram when calculating the band gap width of the ultraviolet spectrum of the I-doped modified Cu2O composite photocatalytic nitrogen fixation material prepared in Example 1, Example 2 and Example 6 of the present invention, wherein a is the UV-Vis DRS spectrum and b is the hv~(αhv)2 spectrum.

[0029] Figure 12 The photoluminescence spectra of the composite photocatalytic nitrogen fixation materials of I-doped modified Cu2O prepared in Examples 1, 2 and 6 of the present invention.

[0030] Figure 13 These are AC impedance curves of the composite photocatalytic nitrogen fixation materials of I-doped modified Cu2O prepared in Examples 1, 2, and 6 of the present invention, where a is the photoinduced current-time image and b is the AC impedance curve.

[0031] Figure 14 Mott-Schottky test results of the I-doped modified Cu2O composite photocatalytic nitrogen fixation material prepared in Example 1, Example 2 and Example 6 of the present application, wherein a is the Mott-Schottky plot of S0 in Example 1, b is the Mott-Schottky plot of S1 in Example 2, c is the Mott-Schottky plot of S2 in Example 1, and d is the Mott-Schottky plot of S3 in Example 6.

[0032] Figure 15 VB XPS test plot of the I-doped modified Cu2O composite photocatalytic nitrogen fixation material prepared in Example 1 of the present application.

[0033] Figure 16 Nitrogen fixation reaction mechanism plot of the I-doped modified Cu2O composite photocatalytic nitrogen fixation material of the present application. DETAILED DESCRIPTION

[0034] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in connection with the drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0036] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0037] In the description of the embodiments of the present application, it should be noted that if the terms “upper”, “lower”, “horizontal”, “inner” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the present application is used, it is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application. In addition, the terms “first”, “second” and the like are only used for differentiation in description, and cannot be understood as indicating or implying relative importance.

[0038] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0039] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0040] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0041] See also Figure 1 The present invention discloses a method for preparing a composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O, comprising: S1: Evenly mix the copper acetate solution, the NaOH solution, and the glucose solution to obtain a first mixed solution, specifically: add a NaOH solution with a concentration of 0.7 to 0.9 mol / L and a glucose solution with a concentration of 1 to 1.5 mol / L to a copper acetate solution with a concentration of 0.15 to 0.25 g / mL, so that the volume ratio of the copper acetate solution, the NaOH solution, and the glucose solution is 3:1:1, to obtain a first mixed solution; note that when adding the NaOH solution, the addition rate of the NaOH solution is controlled at 0.1 to 0.3 mL / s, and stirring is performed while adding.

[0042] S2: Add polyvinyl pyrrolidone to the first mixed solution and heat to react to obtain reactant S0, specifically: Adding polyvinyl pyrrolidone to the first mixed solution to make the concentration of polyvinyl pyrrolidone 0.01 to 0.04 g / mL, ultrasonically mixing to obtain a second mixed solution, and placing the second mixed solution at 80° C. to 100° C. for 10 to 18 hours to obtain a reactant S0; S3: adding KI to the reactant S0 and performing a hydrothermal reaction to obtain a composite photocatalytic nitrogen fixation material.

[0043] KI was added to reactant S0 to a concentration of 0.0002-0.0004 g / mL. The mixture was ultrasonically shaken for 30 minutes to obtain a mixed solution. This solution was transferred to a 50 mL polytetrafluoroethylene-lined reactor and reacted at 120-140°C for 18-24 hours. After cooling to room temperature, the mixture was washed three times with anhydrous ethanol and deionized water, then placed in an oven and dried to obtain a composite photocatalytic nitrogen fixation material (I-Cu2O).

[0044] Example 1 0.6 g of copper acetate (Cu(CH3COO)2) was dissolved in 30 mL of deionized water, and 10 mL of 0.8 mol / L NaOH solution was slowly added dropwise. After ultrasonication for 10 minutes, 10 mL of 1.1 mol / L glucose solution and 1 g of polyvinyl pyrrolidone were added. After ultrasonication for 20 minutes, the mixed solution was placed in an autoclave and reacted at 90°C for 14 hours to obtain the reactant S0. The reactant S0 was centrifuged, washed with water, and dried to obtain Cu2O particles.

[0045] KI was added to reactant S0 to a concentration of 0.0003 g / mL. The mixture was ultrasonically shaken for 30 minutes to obtain a mixed solution. This solution was transferred to a 50 mL polytetrafluoroethylene-lined reactor and reacted at 130°C for 24 hours. After cooling to room temperature, the mixture was washed three times by alternating centrifugation with anhydrous ethanol and deionized water, then placed in an oven at 60°C and dried for 6 hours to obtain I-Cu2O particles, designated S2.

[0046] Example 2 0.6 g of copper acetate Cu(CH3COO)2 was dissolved in 30 mL of deionized water, and 10 mL of 0.8 mol / L NaOH solution was slowly added dropwise. After ultrasonication for 10 min, 10 mL of 1.1 mol / L glucose solution was added, and 1 g of polyvinyl pyrrolidone was added. After ultrasonication for 20 min, the mixed solution was placed in a high-pressure reactor and reacted at 90°C for 14 h to obtain the reactant S0.

[0047] KI was added to reactant S0 to a concentration of 0.0002 g / mL. The mixture was ultrasonically shaken for 30 minutes to obtain a mixed solution. This solution was transferred to a 50 mL polytetrafluoroethylene-lined reactor and reacted at 130°C for 24 hours. After cooling to room temperature, the mixture was washed three times with anhydrous ethanol and deionized water by centrifugation, then dried in an oven at 60°C for 6 hours to obtain I-Cu2O particles, designated S1.

[0048] Example 3 0.6 g of copper acetate Cu(CH3COO)2was dissolved in 30 mL of deionized water, 10 mL of NaOH solution with a concentration of 0.8 mol / L was slowly added dropwise, 10 mL of glucose solution with a concentration of 1.1 mol / L was added after ultrasonic treatment for 10 min, 2 g of polyvinylpyrrolidone was added, and the mixed solution was placed in a high-pressure reaction kettle after ultrasonic treatment for 20 min, and reacted at 90°C for 14 h to obtain a reactant S0.

[0049] KI was added to the reactant S0 so that the concentration of KI was 0.0003 g / mL, and the final mixed solution was obtained after ultrasonic treatment for 30 min. It was moved into a 50 mL polytetrafluoroethylene-lined reaction kettle and reacted at 130°C for 24 h. After cooling to room temperature, it was washed with anhydrous ethanol and deionized water alternately by centrifugation for 3 times, and then placed in an oven at a temperature of 60°C for drying for 6 h to obtain I-Cu2O microparticles.

[0050] Example 4 0.6 g of copper acetate Cu(CH3COO)2was dissolved in 30 mL of deionized water, 10 mL of NaOH solution with a concentration of 0.8 mol / L was slowly added dropwise, 10 mL of glucose solution with a concentration of 1.1 mol / L was added after ultrasonic treatment for 10 min, 1.5 g of polyvinylpyrrolidone was added, and the mixed solution was placed in a high-pressure reaction kettle after ultrasonic treatment for 20 min, and reacted at 90°C for 14 h to obtain a reactant S0.

[0051] KI was added to the reactant S0 so that the concentration of KI was 0.0003 g / mL, and the final mixed solution was obtained after ultrasonic treatment for 30 min. It was moved into a 50 mL polytetrafluoroethylene-lined reaction kettle and reacted at 130°C for 24 h. After cooling to room temperature, it was washed with anhydrous ethanol and deionized water alternately by centrifugation for 3 times, and then placed in an oven at a temperature of 60°C for drying for 6 h to obtain I-Cu2O microparticles.

[0052] Example 5 0.6 g of copper acetate Cu(CH3COO)2was dissolved in 30 mL of deionized water, 10 mL of NaOH solution with a concentration of 0.8 mol / L was slowly added dropwise, 10 mL of glucose solution with a concentration of 1.1 mol / L was added after ultrasonic treatment for 10 min, 1 g of polyvinylpyrrolidone was added, and the mixed solution was placed in a high-pressure reaction kettle after ultrasonic treatment for 20 min, and reacted at 90°C for 18 h to obtain a reactant S0.

[0053] KI was added to the reactant S0 so that the concentration of the KI was 0.0003 g / mL, and ultrasonic oscillation was performed for 30 min, and finally a mixed solution was obtained. It was moved into a 50 mL polytetrafluoroethylene-lined reaction kettle, and reacted at 130°C for 24 h. After being cooled to room temperature, it was washed by centrifugation with anhydrous ethanol and deionized water alternately for 3 times, and was placed into an oven with a temperature of 60°C, and dried for 6 h to obtain I-Cu2O microparticles.

[0054] Example 6 0.6 g of copper acetate Cu(CH3COO)2 was dissolved in 30 mL of deionized water, 10 mL of a NaOH solution with a concentration of 0.8 mol / L was slowly added dropwise, 10 mL of a glucose solution with a concentration of 1.1 mol / L was added after ultrasonic oscillation for 10 min, 1 g of polyvinylpyrrolidone was added, and the mixed solution was placed into a high-pressure reaction kettle after ultrasonic oscillation for 20 min, and reacted at 90°C for 14 h to obtain a reactant S0.

[0055] KI was added to the reactant S0 so that the concentration of the KI was 0.0004 g / mL, and ultrasonic oscillation was performed for 30 min, and finally a mixed solution was obtained. It was moved into a 50 mL polytetrafluoroethylene-lined reaction kettle, and reacted at 130°C for 24 h. After being cooled to room temperature, it was washed by centrifugation with anhydrous ethanol and deionized water alternately for 3 times, and was placed into an oven with a temperature of 60°C, and dried for 6 h to obtain I-Cu2O microparticles, which was recorded as S3.

[0056] Comparative Example 1 0.6 g of CuSO4 was dissolved in 30 mL of deionized water, 10 mL of a NaOH solution with a concentration of 0.8 mol / L was slowly added dropwise, 10 mL of a glucose solution with a concentration of 1.1 mol / L was added after ultrasonic oscillation for 10 min, 10 g of polyvinylpyrrolidone was added, and the mixed solution was placed into a high-pressure reaction kettle after ultrasonic oscillation for 20 min, and reacted at 90°C for 14 h to obtain a mixed solution.

[0057] KI was added to the mixed solution so that the concentration of the KI was 0.0003 g / mL, and ultrasonic oscillation was performed for 30 min, and finally a mixed solution was obtained. It was moved into a 50 mL polytetrafluoroethylene-lined reaction kettle, and reacted at 130°C for 24 h. After being cooled to room temperature, it was washed by centrifugation with anhydrous ethanol and deionized water alternately for 3 times, and was placed into an oven with a temperature of 60°C, and dried for 6 h to obtain a composite photocatalytic nitrogen fixation material.

[0058] Comparative Example 2 Dissolve 0.6 g of copper acetate Cu(CH3COO)2 in 30 mL of deionized water, slowly add 10 mL of 0.8 mol / L NaOH solution, ultrasonicate for 10 min, add 10 mL of 1.1 mol / L glucose solution, ultrasonicate for 20 min, place the mixed solution in a high-pressure reactor, and react at 90°C for 14 h to obtain a mixed solution.

[0059] KI was added to the mixed solution to a concentration of 0.0002 g / mL. The solution was ultrasonically shaken for 30 minutes to obtain a mixed solution. The solution was then transferred to a 50 mL polytetrafluoroethylene-lined reactor and reacted at 130°C for 24 hours. After cooling to room temperature, the solution was washed three times with anhydrous ethanol and then with deionized water by centrifugation. The solution was then placed in an oven at 60°C and dried for 6 hours to obtain a composite photocatalytic nitrogen fixation material.

[0060] To further illustrate the beneficial effects of the present invention, the products obtained in Examples 1-6 and Comparative Examples 1-2 were tested (except Figure 1 In addition, S0 in the remaining test result diagram represents the product after the reactant S0 is centrifuged, washed, and dried, S1 is the product prepared in Example 2, S2 is the product prepared in Example 1, and S3 is the product prepared in Example 6). Figure 2 From the XRD patterns of Examples 1, 2, and 6, it can be seen that the diffraction peaks are consistent with the Cu2O crystal plane in the standard card (JCPDS No. 05-0667), and no impurity peaks appear. The peak positions of I-Cu2O and Cu2O particles are shifted to the left to varying degrees, indicating that iodine has been successfully incorporated into the crystal lattice of the Cu2O particles. The intensity of the diffraction peak of the (111) crystal plane of the I-Cu2O particles increases, indicating that the I-Cu2O particles preferentially grow along the (111) crystal plane. The (111) crystal plane of the S2 particles corresponding to the addition amount of Example 1 has the highest diffraction peak. Sample S2 has the highest purity and has good crystallinity and catalytic activity.

[0061] See also Figure 3 The XRD pattern of the composite photocatalytic nitrogen fixation material of I-doped modified Cu2O prepared in Example 1 shows that when the copper source is copper acetate, sharp diffraction peaks of Cu2O appear at 2θ of 29.63°, 36.4°, 42.3°, 61.37°, 74.4°, and 77.75°, corresponding to the (110), (111), (200), (220), and (311) crystal planes of Cu2O, which are consistent with the Cu2O crystal planes in the standard card (JCPDS No.05-0667), and no other miscellaneous peaks appear. In Comparative Example 1, when the copper source is copper sulfate, over-reduction occurs during the reaction, and miscellaneous peaks of copper element appear, and their diffraction peaks are all weak.

[0062] Referring to Figure 4 , when the reaction time is 14 h, the I-Cu2O microparticles prepared in Example 1 have the highest diffraction peak of the (111) crystal face, and the crystal face has a good catalytic performance due to the preferred growth. Moreover, under this condition, the I-Cu2O microparticles have the largest ratio of the (111) crystal face to the (200) crystal face. The ratio of the (111) crystal face to the (200) crystal face can also indirectly indicate the electron-hole separation efficiency of the I-Cu2O microparticles. The larger the ratio, the higher the separation efficiency.

[0063] Referring to Figure 5 , with the increase of the amount of polyvinylpyrrolidone in the example, the intensity of the diffraction peak of the prepared I-Cu2O microparticles first increases and then decreases, and a copper impurity peak appears. When the amount of the additive is 10 g, the I-Cu2O microparticles have the highest diffraction peak of the (111) crystal face, and the I-Cu2O microparticles have the largest ratio of the (111) crystal face to the (200) crystal face.

[0064] Referring to Figure 6 , when the temperature is 80℃ in Example 2 and 100℃, multiple impurity peaks appear. When the temperature is 90℃, the prepared I-Cu2O microparticles have the highest purity and the best crystallinity, and the I-Cu2O microparticles prepared in Example 1 have the best performance.

[0065] Referring to Figure 7 , Figure (a) is an XPS full spectrum diagram, which shows that the prepared I-Cu2O is composed of O, Cu and I elements. Figure (b) is a high-resolution XPS spectrum of Cu 2p, which shows that the copper element in the sample exists in the form of Cu+. Figure (c) is a high-resolution spectrum of O 1s, and three peaks are obtained by XPS Peak fitting, which correspond to oxygen in the Cu2O lattice, oxygen vacancy defects and chemisorbed oxygen. Figure (d) is a high-resolution XPS spectrum of I 3d, which shows that iodine is doped into the Cu2O lattice in the form of I-.

[0066] Referring to Figure 8 , with the increase of the amount of KI added, the morphology of the I-Cu2O microparticles changes from the original regular spherical shape to a cubic shape. The doping of I into the Cu2O lattice causes distortion of the Cu2O lattice, which affects the growth of the microcrystals and causes the change of the morphology. The morphology of S2 changes from a spherical shape to a cubic shape, and the size is relatively uniform.

[0067] Referring to Figure 9 , Figure is an EDAX spectrum of the S2 microparticles. It can be seen that the S2 microparticles are mainly composed of Cu, O, I and other elements, which also shows that the I element successfully enters the Cu2O lattice.

[0068] Referring to Figure 10 , compared with other samples, the sample S2 has a large specific surface area.

[0069] See also Figure 11-14 The results of UV-visible diffuse reflectance spectroscopy analysis show that the absorption edge of the I-Cu2O particles is blue-shifted and the band gap is increased. The photoelectric performance analysis shows that the carrier concentration of the sample is increased after iodine doping modification. The photoluminescence analysis results show that the probability of photogenerated electron-hole recombination in the I-Cu2O particles is reduced. In order to further analyze the effect of iodine doping on the valence band position, VB XPS test was performed on the I-Cu2O particles in Example 1. The results are as follows: Figure 15 The valence band (VB) of the I-Cu2O particles in Example 1 is 1.84 eV. The conduction band (CB) of the I-Cu2O particles in Example 1 is calculated to be -0.21 eV based on the band gap fitted by the formula.

[0070] Eg=EVB-ECB Where: Eg is the band gap, EVB is the valence band value, and ECB is the conduction band value.

[0071] The present invention also provides a composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O, which is prepared using the above-mentioned preparation method. The composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O is an n-type Cu2O semiconductor material. The reaction mechanism of nitrogen fixation and ammonia synthesis by the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O is shown in FIG. Figure 16 When irradiated with light, electrons in the valence band jump to the conduction band under photoexcitation, generating highly active electrons in the conduction band and positively charged holes in the valence band. Electrons are highly reducing, while holes are highly oxidizing, inducing reactions in organic matter. A pn ​​homojunction is formed, and the electron transfer process first migrates from the n-type Cu2O semiconductor material to the surface of the p-type semiconductor material, thereby improving the separation efficiency of photogenerated electron-hole pairs. At the same time, the holes generated by the electron transition in the p-type semiconductor are firmly attracted by the iodide ions doped in the n-type semiconductor material, thereby increasing the carrier concentration and further improving the photocatalytic performance of the sample. This I-doped modified Cu2O composite photocatalytic nitrogen fixation material can provide a stronger reduction driving force in photocatalytic nitrogen fixation, increase the ammonia production rate, and achieve comprehensive optimization of N2 reduction thermodynamics, carrier separation kinetics, surface reaction activity, and material stability, providing a key energy band engineering strategy for the design of efficient and stable photocatalytic nitrogen fixation materials.

[0072] For example, the application of the aforementioned I-doped Cu2O composite photocatalytic nitrogen fixation material in photocatalytic nitrogen fixation. Due to its wider light absorption range, low carrier recombination probability, and excellent stability and cyclability, this I-doped Cu2O composite photocatalytic nitrogen fixation material exhibits improved light utilization, enhanced redox capacity, and lower energy barriers in photocatalytic nitrogen fixation. This provides a viable alternative to the industrial Haber-Bosch process (high temperature, high pressure, and high energy consumption), promoting the development of efficient and stable photocatalytic nitrogen fixation.

[0073] The above merely describes the preferred embodiments of the present application, and is not intended to limit the technical solutions of the present application in any way. Those skilled in the art should understand that, without departing from the spirit and principle of the present application, the technical solutions can also be modified and replaced in several simple ways, and these modifications and replacements also all fall within the protection scope encompassed by the claims.

Claims

1. A method for preparing a composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O, characterized in that: include: Evenly mixing the copper acetate solution, the NaOH solution and the glucose solution to obtain a first mixed solution; Adding polyvinyl pyrrolidone to the first mixed solution and heating for reaction to obtain a reactant S0; KI is added to the reactant S0 and a hydrothermal reaction is carried out to obtain a composite photocatalytic nitrogen fixation material.

2. The method for preparing the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O according to claim 1, characterized in that: The concentration of the copper acetate solution is 0.15-0.25 g / mL.

3. The method for preparing the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O according to claim 2, characterized in that: The concentration of the NaOH solution is 0.7-0.9 mol / L.

4. The method for preparing the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O according to claim 3, characterized in that: The concentration of the glucose solution is 1-1.5 mol / L.

5. The method for preparing the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O according to claim 4, characterized in that: The volume ratio of the copper acetate solution, the NaOH solution and the glucose solution is 3:1:

1.

6. The method for preparing the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O according to claim 1, characterized in that: The concentration of polyvinyl pyrrolidone after adding polyvinyl pyrrolidone to the first mixed solution is 0.01-0.04 g / mL.

7. The method for preparing the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O according to claim 1, characterized in that: The heating reaction conditions are 80° C. to 100° C., and the reaction time is 10 to 18 hours.

8. The method for preparing the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O according to claim 1, characterized in that: After KI is added to the reactant S0, the concentration of KI is 0.0002-0.0004 g / mL, and the hydrothermal reaction condition is 120°C-140°C.

9. A composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the composite photocatalytic nitrogen-fixing material of I-doped modified Cu2O as claimed in claim 9 in photocatalytic nitrogen fixation.

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