Preparation of a supported copper alloy nanocluster catalyst and its application in photocatalytic degradation

Abstract

This invention discloses a supported Au1Cu 24 Preparation of / g-C3N4 catalyst and its application in photocatalytic degradation. This catalyst utilizes Au1Cu 24 Copper alloy nanoclusters supported on a g-C3N4 support were constructed to address the problems of low efficiency, rapid electron-hole recombination, and poor stability in existing photocatalytic materials. The preparation steps are as follows: first, a g-C3N4 support is prepared, and then Au1Cu is synthesized. 24 Clusters, then Au1Cu 24 A composite catalyst was obtained by dispersing the catalyst in dichloromethane and mixing it with g-C3N4, followed by solvent evaporation. This design effectively suppressed photogenerated carrier recombination and significantly improved photocatalytic activity and stability by modulating the cluster electronic structure and charge distribution through heterometallic doping, combined with the anchoring of the active component by the g-C3N4 support and its role in promoting interfacial charge separation. When applied to the photocatalytic degradation of methylene blue under xenon lamp irradiation, it exhibited excellent degradation performance and cycle stability, with superoxide radicals (·O2) as the main active species. ‑ ) and holes (h + This invention provides a new technical solution for the efficient treatment of organic dye wastewater.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials and environmental catalysis technology, specifically relating to a supported copper alloy nanocluster catalyst Au1Cu. 24 Preparation method of / g-C3N4 and its application in the photocatalytic degradation of the organic dye methylene blue. Background Technology

[0002] Dye wastewater, due to its high color intensity, high organic content, complex composition, and difficulty in degradation, poses a serious threat to aquatic ecosystems and human health if directly discharged. Photocatalytic degradation technology, with its mild reaction conditions (room temperature and pressure), environmental friendliness, and light-driven pollutant mineralization capabilities, has become a key direction for organic wastewater treatment. For the highly environmentally hazardous typical pollutant methylene blue, developing efficient photocatalytic materials is the core approach to improving degradation efficiency. Atomically precise metal nanoclusters, with their tunable electronic structure and atomic-level structure-activity relationship analysis, show significant promise in the field of photocatalysis. Alloy nanoclusters formed by heterometallic doping can improve the separation and migration of photogenerated carriers by controlling electronic structure and charge distribution, thereby enhancing catalytic activity. Au1Cu 24 As a copper alloy nanocluster, it possesses excellent potential for photocatalytic applications. However, when used alone, it suffers from insufficient dispersibility, limited stability, and difficulties in recovery. Therefore, it requires a support to overcome these application bottlenecks. Graphitic carbon nitride (g-C3N4), due to its visible light response characteristics, abundant nitrogen coordination sites, and excellent chemical stability, can both anchor metal clusters to improve dispersion / stability and promote interfacial charge separation, thereby enhancing overall photocatalytic performance. Based on this, a g-C3N4-supported Au1Cu nanocluster was developed. 24 The composite catalyst and its application in the photocatalytic degradation of methylene blue have significant application value for the efficient treatment of organic dye wastewater. Summary of the Invention

[0003] The technical problem to be solved by this invention is: to address the problems of low catalytic efficiency, rapid recombination of photogenerated electrons and holes, and insufficient dispersion and stability of active components in the treatment of organic dye wastewater by existing photocatalytic materials, and to provide a method for preparing a supported copper alloy nanocluster catalyst and its application in photocatalytic degradation.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A supported copper alloy nanocluster catalyst, wherein the catalyst is Au1Cu 24 / g-C3N4 composite catalyst, wherein Au1Cu 24 The structure consists of copper alloy nanoclusters, with g-C3N4 serving as a graphitic carbon nitride support.

[0006] The preparation method of the supported copper alloy nanocluster catalyst includes the following steps:

[0007] (1) Preparation of g-C3N4 support: After the nitrogen-containing precursor is mixed evenly, it is dried and calcined to obtain graphitic carbon nitride g-C3N4 support;

[0008] (2) Preparation of Au1Cu 24 Copper alloy nanoclusters: A copper source was dissolved in an organic mixed solvent, a phosphine ligand was added under stirring, and a reducing agent was added to carry out a reduction reaction. After aging and low-temperature crystallization, Au1Cu was obtained. 24 Copper alloy nanoclusters;

[0009] (3) Preparation of Au1Cu 24 / g-C3N4 composite catalyst: Au1Cu 24 Copper alloy nanoclusters were dispersed in an organic solvent, and a g-C3N4 support was added and stirred to load the metal clusters onto the g-C3N4 surface. After the solvent evaporated, Au1Cu was obtained. 24 / g-C3N4 composite catalyst.

[0010] Preferably, the nitrogen-containing precursor in step (1) includes melamine and urea.

[0011] Preferably, in step (1), the nitrogen-containing precursor is ultrasonically and stirred, dried at 80°C, and then calcined at high temperature under a N2 protective atmosphere to obtain the g-C3N4 carrier.

[0012] Preferably, in step (1), the calcination temperature is 550°C, the heating rate is 5°C / min, and the holding time is 3h.

[0013] Preferably, in step (2), the copper source is copper acetylacetonate, the phosphine ligand is tris(p-fluorophenyl)phosphine, and the reducing agent is sodium borohydride.

[0014] Preferably, in step (2), the organic mixed solvent is a mixture of methanol and dichloromethane.

[0015] Preferably, in step (2), the reduction reaction temperature is 36°C, the reaction is aged for 5 hours, and crystallization is carried out at low temperature to obtain Au1Cu. 24 Copper alloy nanoclusters.

[0016] Preferably, in step (3), the Au1Cu 24 The mass ratio of copper alloy nanoclusters to g-C3N4 support is 3:97.

[0017] Preferably, in step (3), the organic solvent is dichloromethane.

[0018] The present invention also provides the Au1Cu 24 Application of / g-C3N4 composite catalyst in photocatalytic degradation of organic pollutants.

[0019] Preferably, the organic pollutant is methylene blue.

[0020] Preferably, the photocatalytic degradation method includes: dissolving Au1Cu 24 The / g-C3N4 composite catalyst was added to a methylene blue solution, stirred under light-protected conditions to allow the system to reach adsorption-desorption equilibrium, and then subjected to photocatalytic degradation under light conditions.

[0021] Preferably, the concentration of the methylene blue solution is 10 mg / L, the reaction volume is 20 mL, the amount of catalyst is 10 mg, and the dark reaction time is 30 min.

[0022] Preferably, the illumination conditions are xenon lamp irradiation, continuous stirring is carried out during the reaction, and the reaction temperature is controlled at 20°C by circulating cooling water.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) This invention uses Au1Cu 24 Copper alloy nanoclusters, as active components, utilize the regulatory effect of heterometallic doping on the electronic structure and charge distribution of the clusters, which is beneficial to improving the separation and migration of photogenerated carriers, thereby enhancing photocatalytic activity.

[0025] (2) This invention uses g-C3N4 as a carrier, which can effectively improve Au1Cu 24 The dispersion and stability of copper alloy nanoclusters reduce agglomeration and loss, and facilitate the recycling of catalysts.

[0026] (3) Au1Cu constructed in this invention 24 The / g-C3N4 composite catalyst can promote interfacial charge transfer and inhibit photogenerated electron-hole pair recombination, thereby improving the photocatalytic degradation performance of methylene blue.

[0027] (4) The preparation method described in this invention is simple, easy to operate, and has good repeatability. The resulting composite catalyst has good application prospects. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below:

[0029] Figure 1 Au1Cu 24 Schematic diagram of the structure of copper alloy nanoclusters;

[0030] Figure 2 Au1Cu 24 UV-Vis absorption spectrum of copper alloy nanoclusters;

[0031] Figure 3 Au1Cu 24 Transmission electron microscopy image of the / g-C3N4 supported catalyst;

[0032] Figure 4 Au1Cu 24 X-ray diffraction pattern of / g-C3N4 supported catalyst;

[0033] Figure 5 Au1Cu 24 UV-Vis diffuse reflectance absorption spectrum of / g-C3N4 supported catalyst;

[0034] Figure 6 Au1Cu 24 X-ray photoelectron spectroscopy of the / g-C3N4 supported catalyst;

[0035] Figure 7 Au1Cu 24 Electrochemical impedance spectroscopy of the / g-C3N4 supported catalyst;

[0036] Figure 8 Au1Cu 24 Transient photocurrent response of the / g-C3N4 supported catalyst;

[0037] Figure 9 Au1Cu 24 Fluorescence emission spectrum of / g-C3N4 supported catalyst;

[0038] Figure 10 Au1Cu 24 Photocatalytic degradation efficiency of methylene blue by / g-C3N4 catalyst;

[0039] Figure 11 Au1Cu 24 Cyclic stability test diagram of / g-C3N4 catalyst for photocatalytic degradation of methylene blue;

[0040] Figure 12 Au1Cu 24 Experimental diagram of active species capture during the photocatalytic degradation of methylene blue using / g-C3N4 catalyst. Detailed Implementation

[0041] To further clarify the technical solution and beneficial effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the following embodiments are only used to explain the present invention and should not be construed as limiting the scope of protection of the present invention.

[0042] Unless otherwise specified, the raw materials, reagents and testing methods used in the examples are all conventional methods in the art, and all reagents used can be obtained commercially.

[0043] The Au1Cu of this invention 24 / g-C3N4 composite catalyst made of Au1Cu 24 Copper alloy nanoclusters were prepared by loading them onto a graphitic carbon nitride support and can be used for the photocatalytic degradation of methylene blue.

[0044] Example 1: Preparation of g-C3N4 support

[0045] The preparation method of g-C3N4 support includes the following steps:

[0046] Weigh 3.00 g of urea and dissolve it in a small amount of deionized water. Then add 6.30 g of melamine and sonicate the resulting mixture for 30 min. Stir at room temperature for 2 h to ensure uniform mixing. Dry the resulting mixture at 80 °C for 24 h and grind it into powder. Place the powder in a tube furnace and heat it to 550 °C at a heating rate of 5 °C / min under a nitrogen atmosphere. Hold the temperature for 3 h and then cool it naturally to room temperature to obtain yellow g-C3N4 powder, which is the carrier material.

[0047] Example 2: Au1Cu 24 Preparation of copper alloy nanoclusters

[0048] 1800 mg of copper acetylacetonate was dissolved in a mixed solvent of 125 mL methanol and 375 mL dichloromethane in a 1000 mL round-bottom flask and stirred vigorously for 30 min in an oil bath at 36 °C. 3000 mg of tris(p-fluorophenyl)phosphine was rapidly added to the reaction solution, causing the system color to change from dark blue to light blue. Then, fresh sodium borohydride aqueous solution, pre-cooled in an ice bath and prepared by dissolving 1500 mg of sodium borohydride in 20 mL of deionized water, was rapidly added. After addition, the color of the reaction solution gradually changed from light blue to light brown within 1 h. The reaction was then aged for another 5 h after completion. Subsequently, a small amount of ethanol was added to a dichloromethane / n-hexane mixed solvent, and the mixture was placed at -4 °C for approximately 2 days to obtain Au1Cu. 24 Copper alloy nanocluster crystals. For example... Figure 1 and Figure 2 As shown, the prepared Au1Cu 24Copper alloy nanoclusters exhibit distinct structural characteristics and corresponding UV-Vis absorption features.

[0049] Example 3: Au1Cu 24 Preparation of / g-C3N4 composite catalyst

[0050] Weigh 3 mg of Au1Cu prepared in Example 2 24 Copper alloy nanoclusters were dispersed in 10 mL of dichloromethane; 97 mg of g-C3N4 powder prepared in Example 1 was added to the dispersion, and the mixture was stirred continuously at room temperature until the solvent was completely evaporated; after solvent evaporation, uniformly dispersed Au1Cu was obtained. 24 / g-C3N4 composite catalyst powder. The morphology characterization of the obtained composite catalyst is as follows: Figure 3 As shown, the X-ray diffraction pattern is as follows Figure 4 As shown, the ultraviolet-visible diffuse reflectance absorption spectrum is as follows: Figure 5 As shown, the X-ray photoelectron spectrum is as follows: Figure 6 As shown, the electrochemical impedance spectroscopy is as follows: Figure 7 As shown, the transient photocurrent response diagram is as follows: Figure 8 As shown, the fluorescence emission spectrum is as follows: Figure 9 As shown.

[0051] Example 4: Au1Cu 24 Performance of / g-C3N4 composite catalyst in photocatalytic degradation of methylene blue

[0052] Au1Cu prepared in Example 3 was processed using a photocatalytic reaction device. 24 The photocatalytic degradation performance of the / g-C3N4 composite catalyst was tested. 24 A 10 mg / L methylene blue solution was added to a 1g-C3N4 composite catalyst. Before the reaction, the reactor was wrapped with aluminum foil and magnetically stirred in the dark for 30 min to allow the catalyst and methylene blue to reach adsorption-desorption equilibrium. After the dark reaction, a xenon lamp was used as the light source for irradiation, and the photocatalytic reaction was carried out under continuous stirring. The reaction temperature was controlled at 20℃ using circulating cooling water. Samples were taken every 30 min from the start of irradiation. The samples were immediately filtered to remove catalyst particles, and the resulting supernatant was subjected to UV-Vis absorption spectroscopy. The concentration and degradation rate of methylene blue were calculated based on the intensity changes of the characteristic absorption peak. Figure 10 As shown, the Au1Cu of the present invention 24 The / g-C3N4 composite catalyst exhibits excellent photocatalytic degradation performance for methylene blue.

[0053] The Au1Cu of this invention 24The degradation rate of methylene blue by the / g-C3N4 composite catalyst is calculated using the following formula:

[0054] Degradation rate (%) = (C0 - C) t ) / C0×100%.

[0055] Where C0 is the initial concentration of methylene blue, C t The concentration of methylene blue at time t during the reaction is given.

[0056] Example 5: Au1Cu 24 Cyclic stability test of / g-C3N4 composite catalyst

[0057] To investigate the Au1Cu described in this invention 24 The recycling performance of the / g-C3N4 composite catalyst was tested under the same reaction conditions as in Example 4, i.e., the concentration of methylene blue solution, solution volume, catalyst dosage, light conditions, and reaction time were kept consistent. After each photocatalytic degradation reaction, the catalyst was recovered by centrifugation and placed in deionized water for treatment under light conditions to remove residual methylene blue adsorbed on its surface before being used in the next cycle experiment.

[0058] Au1Cu was processed using the method described above. 24 The / g-C3N4 composite catalyst underwent repeated reuse testing. For example... Figure 11 As shown, after multiple cycles, the composite catalyst still maintains a high methylene blue degradation efficiency, indicating that it has good cycle stability and reusability.

[0059] Example 6: Au1Cu 24 / g-C3N4 composite catalyst active species capture experiment

[0060] To investigate the Au1Cu described in this invention 24 The / g-C3N4 composite catalyst is the main active species in the photocatalytic degradation of methylene blue. Based on the photocatalytic degradation system described in Example 4, different scavenging agents were added for comparative experiments. Before the dark adsorption step, 2.2 mg of p-benzoquinone was added to the reaction system as a superoxide radical (O2). − Add 1.0 mL of isopropanol as a hydroxyl radical (·OH) scavenger and 1.0 mL of triethanolamine as a hole scavenger. + The trapping agent, 3.4 mg of silver nitrate, was added as an electron capture agent. − The trapping agent was used, and the remaining experimental conditions were the same as in Example 4.

[0061] Under the same light and reaction conditions, the changes in methylene blue degradation efficiency before and after the addition of different scavengers were compared to analyze the role of each active species in the photocatalytic reaction.

[0062] like Figure 12 As shown, the degradation efficiency of methylene blue decreased to varying degrees after the addition of different scavenging agents, with the decrease being more pronounced after the addition of p-benzoquinone and triethanolamine. This indicates that the degradation efficiency of superoxide radicals (O2) decreased significantly. − and holes h+ in the Au1Cu of this invention 24 The / g-C3N4 composite catalyst plays a major role in the photocatalytic degradation of methylene blue.

[0063] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A supported copper alloy nanocluster catalyst, characterized in that: The catalyst uses graphitic carbon nitride as a support, and the copper alloy nanoclusters supported on the surface of the support are Au1Cu. 24 Nanoclusters.

2. The supported copper alloy nanocluster catalyst according to claim 1, characterized in that: Au1Cu 24 The core of the nanoclusters is AuCu 12 The molecular formula is AuCu 24 H 22 (C 18 H 12 F3P) 12 .

3. The method for preparing the supported copper alloy nanocluster catalyst according to claim 1 or 2, characterized in that: Includes the following steps: (1) After the nitrogen-containing precursor is mixed evenly, it is dried and calcined to obtain a graphitic carbon nitride support; (2) Dissolve the copper source in an organic mixed solvent, add phosphine ligands under stirring, then add a reducing agent to carry out the reduction reaction, and obtain Au1Cu after aging and low-temperature crystallization. 24 Copper alloy nanoclusters; (3) Au1Cu 24 Copper alloy nanoclusters were dispersed in an organic solvent, and the graphitic carbon nitride support was added and stirred to allow Au1Cu to disperse. 24 Copper alloy nanoclusters were supported on the surface of a graphitic carbon nitride support, and the supported copper alloy nanocluster catalyst was obtained after the solvent evaporated.

4. The preparation method according to claim 3, characterized in that: The nitrogen-containing precursors in step (1) include melamine and urea; the drying temperature is 80°C; the calcination is carried out under a N2 protective atmosphere, the calcination temperature is 550°C, the heating rate is 5°C / min, and the holding time is 3 h.

5. The preparation method according to claim 3, characterized in that: In step (2), the copper source is copper acetylacetonate, the phosphine ligand is tris(p-fluorophenyl)phosphine, the reducing agent is sodium borohydride, the organic mixed solvent is a mixture of methanol and dichloromethane, the reduction reaction temperature is 36°C, and the aging time is 5 h.

6. The preparation method according to claim 3, characterized in that: In step (3), the Au1Cu 24 The mass ratio of copper-gold alloy nanoclusters to graphite-phase carbon nitride support is 3:97, and the organic solvent is dichloromethane.

7. The application of the supported copper alloy nanocluster catalyst according to claim 1 or 2 in the photocatalytic degradation of organic pollutants.

8. The application according to claim 7, characterized in that: The organic pollutant is methylene blue.

9. The application according to claim 7 or 8, characterized in that: The supported copper alloy nanocluster catalyst was added to a methylene blue solution, and the adsorption-desorption equilibrium was first achieved by stirring under light-protected conditions. Then, a photocatalytic degradation reaction was carried out under light conditions.

10. The application according to claim 9, characterized in that: The concentration of the methylene blue solution was 10 mg / L, the reaction volume was 20 mL, the amount of catalyst was 10 mg, and the stirring time in the dark was 30 min. The illumination conditions were xenon lamp irradiation, continuous stirring was carried out during the reaction, and the reaction temperature was controlled at 20℃ by circulating cooling water.

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