Preparation method of graphdiyne / indium oxide nanotube composite photocatalyst

Abstract

This invention relates to the field of nanomaterials technology, specifically a method for preparing a hollow graphdiyne / indium oxide nanotube photocatalyst. First, indium oxide nanorods are synthesized as a precursor using a solvothermal method. These nanorods are then calcined in N2 under vacuum. Next, a flask containing carbon-coated hollow indium oxide nanotubes is evacuated to create a negative pressure inside the nanotubes, which are then immersed in a mixed aqueous solution of cuprous chloride and pyridine, allowing the copper-pyridine complex to penetrate. After centrifugation, excess solution is discarded, leaving only the nanomaterial support. A dichloromethane solution of hexaethynylbenzene is then injected into the reaction system under an argon atmosphere and in a dark chamber to form a thermodynamically stable system. Finally, the product is extracted by centrifugation, washed with anhydrous ethanol, and dried to obtain the hollow graphdiyne / indium oxide nanotube photocatalyst composite material.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, specifically a method for preparing hollow graphdiyne / indium oxide nanotube photocatalysts. Background Technology

[0002] Graphdiyne, a novel two-dimensional carbon material, has attracted widespread attention both domestically and internationally. It is a promising new carbon allotrope, exhibiting properties rarely seen in previously discovered carbon materials due to its unique sp and sp2 electronic structures and intrinsic band gap. Compared to traditional carbon materials, graphdiyne demonstrates significant advantages in synthesis and structure. Its preparation conditions are mild and favorable (typically below 100°C), allowing for large-area in-situ preparation on various substrates in a liquid phase, thus revolutionizing conventional carbon material synthesis methods. Graphdiyne possesses an in-plane porous structure, allowing for precise control of pore size through precursor design, resulting in excellent selective permeability. Heteroatoms and functional groups with specific functions can be precisely used to modify graphdiyne, regulating its band structure and chemical and physical properties. Its tunable mechanical modulus and strength can meet diverse application requirements. The highly conjugated two-dimensional planar structure endows graphdiyne with excellent charge transport and carrier migration capabilities. The sp and sp2 hybridized two-dimensional network of all-carbon structure gives graphdiyne both unique chemical activity and physical stability. Graphdiyne has the characteristics of low temperature and mild growth, so it can be well combined with conventional semiconductor materials to realize the construction of novel heterojunction interfaces.

[0003] Metal oxides are mature semiconductor materials with excellent physical stability, resistance to photocorrosion, and low decomposition at high temperatures, and are simple to prepare. Among various catalyst materials, In₂O₃ has wide applications in gas sensing, solar cells, and other fields due to its suitable band gap, unique high conductivity, and wide band gap. It is a wide-bandgap n-type metal oxide semiconductor, non-toxic, and usually appears as a light yellow powder. It is easy to modify and dope its morphology. In addition to degrading pollutants, it can also be used as a photocatalyst for hydrogen production and carbon dioxide conversion. As a novel amphoteric semiconductor material, In₂O₃ has low resistance, good conductivity, and a suitable band gap, and is receiving increasing attention in various fields of photocatalysis, such as photocatalytic hydrogen production, photocatalytic degradation of organic matter, photocatalytic nitrogen fixation, and photocatalytic carbon dioxide reduction. In₂O₃ prepared by calcining MOF precursors has many advantages compared with some traditional preparation methods. For example, the prepared MOF derivatives can inherit the porous structure of the original MOFs. This structure with internal pores can reflect or scatter incident light to enhance light utilization efficiency and provide more exposed active sites. However, previous studies on In2O3 have mainly focused on its use in gas sensors, with few reports on its use as a photocatalytic CO2 reduction catalyst. Therefore, this work aims to directly use In2O3 as a photocatalyst, measure its catalytic performance, and improve its surface properties and adjust its band position through methods such as semiconductor material composite and metal ion doping, thereby achieving the goal of improving its photocatalytic activity for CO2 reduction. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing hollow graphyne / indium oxide nanotube photocatalysts, which produces graphyne-coated carbon-coated hollow nanotubes with a large specific area and good photogenerated carrier separation characteristics, thereby improving their photocatalytic performance.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a graphdiyne / indium oxide nanotube photocatalyst includes the following steps: Step 1: Take 0.60g of indium nitrate pentahydrate and 0.23g of 2-aminoterephthalic acid, dissolve them in 20 mL of N,N-dimethylformamide, and disperse them under ultrasonication to obtain a uniform suspension; Step 2: Add oleylamine and oleic acid to the suspension prepared in Step 1, and stir at room temperature for 2.5 h to obtain a reddish-brown mixed solution; Step 3: Transfer the mixed solution prepared in Step 2 to a high-pressure reactor and maintain it at a pressure of 100-200 MPa and a temperature of 125-250℃ for 5-8 hours. After the reaction is completed, cool the solution to room temperature, filter it under vacuum, and wash it repeatedly with ethanol and deionized water. Dry the product under vacuum at 60℃ for 8 hours to obtain yellow indium oxide nanorods. Step 4: Wrap the yellow indium oxide nanorods prepared in Step 3 in a ceramic boat with aluminum foil and place it in a tube furnace. Slowly heat the furnace to 450-550℃ in a flowing N2 atmosphere and hold for 2-4 hours. The resulting structure is transformed into a tubular structure by Oswald ripening sintering, yielding black hollow indium oxide nanotubes. Step 5: Place 0.10 g of the hollow indium oxide nanotubes prepared in Step 4 into a flask, add 10 mL of pyridine solution of cuprous chloride, evacuate the flask to form a negative pressure environment inside the flask and maintain it for 6-10 h, centrifuge and pour off the supernatant, and dry the lower layer of indium oxide nanotubes containing pyridine copper complex for 8 h for later use. Step 6: Fill a conical flask wrapped with tin foil with 10 mL of dichloromethane solution, add 0.01-0.05 g of hexaethynylbenzene, add the above-mentioned indium oxide nanotubes containing pyridine copper complex, evacuate under argon atmosphere for 24-30 h, centrifuge, wash repeatedly with ethanol and deionized water, wash three times with ethanol and three times with deionized water respectively, and dry to obtain the graphdiyne / indium oxide nanotube photocatalyst.

[0006] In step two, the molar ratio of indium nitrate pentahydrate to 2-aminoterephthalic acid is 1:1 to 1:3, and the molar concentration of indium nitrate pentahydrate in N,N-dimethylformamide is 0.077 mol / L.

[0007] In step two, the concentration of oleylamine in N,N-dimethylformamide is 0.015 mol / L, and the concentration of oleic acid in N,N-dimethylformamide is 0.008 mol / L.

[0008] In step six, the concentration of hexaethynylbenzene in dichloromethane is 0.1-0.3 mmol / L.

[0009] The heating process of the high-pressure reactor in step three is a programmed temperature rise, with a heating rate of 8-15℃ / min.

[0010] In step four, the tubular furnace calcination process is a programmed temperature rise, with a heating rate of 3-5℃ / min.

[0011] In step five or six, the reaction flask is evacuated to create a negative pressure, with a vacuum degree of -20 to -40 MPa.

[0012] In step five, the concentration of cuprous chloride in pyridine is 0.25-0.5 mol / L; after the reaction is completed, crisscrossing graphyne layers grow on the inner and outer surfaces of the indium oxide nanotubes.

[0013] The method described in this invention first synthesizes indium oxide nanorods as a precursor using a solvothermal method, then further calcines them in N2 under vacuum. Next, a flask containing carbon-coated hollow indium oxide nanotubes is evacuated to create negative pressure inside the nanotubes, which are then immersed in a mixed aqueous solution of cuprous chloride and pyridine, allowing the copper-pyridine complex to penetrate. After centrifugation, excess solution is poured off, leaving only the nanomaterials. A dichloromethane solution of hexaethynylbenzene is then injected into the reaction system under argon and darkness to form a thermodynamically stable system. Finally, the product is extracted by centrifugation, washed with anhydrous ethanol, and dried to obtain a hollow graphdiyne / indium oxide nanotube photocatalyst composite material.

[0014] Compared to existing technologies, the hollow graphdiyne / indium oxide nanotubes prepared in this invention have a specific surface area of ​​86.96-92.76 m². 2 ·g -1 It has more reaction sites. The yellow indium oxide nanorods prepared in step three are wrapped in aluminum foil and placed in a ceramic boat. They are then calcined in a tube furnace at 450-550℃ under a flowing N2 atmosphere for 2-4 hours. Through Oswald sintering, they are transformed into a tubular structure, resulting in black hollow indium oxide nanotubes. The hollow structure of the hollow indium oxide nanotubes allows photons to be reflected and refracted, increasing the light absorption utilization rate by 1.7 times. Attached Figure Description

[0015] Figure 1 The image shows the XRD pattern of the hollow graphdiyne / indium oxide nanotube composite material. Figure 2 This is the Raman spectrum of the hollow graphdiyne / indium oxide nanotube composite material; Figure 3 This is a SEM image of a hollow graphdiyne / indium oxide nanotube composite material; Figure 4 This is a test diagram of the photocatalytic performance of hollow graphdiyne / indium oxide nanotube composite material. Detailed Implementation

[0016] A method for preparing a graphdiyne / indium oxide nanotube photocatalyst includes the following steps: Step 1: Take 0.60g of indium nitrate pentahydrate and 0.23g of 2-aminoterephthalic acid, dissolve them in 20 mL of N,N-dimethylformamide, and disperse them under ultrasonication to obtain a uniform suspension; Step 2: Add oleylamine and oleic acid to the suspension prepared in Step 1, and stir at room temperature for 2.5 h to obtain a reddish-brown mixed solution; Step 3: Transfer the mixed solution prepared in Step 2 to a high-pressure reactor and maintain it at a pressure of 100-200 MPa and a temperature of 125-250℃ for 5-8 hours. After the reaction is completed, cool the solution to room temperature, filter it under vacuum, and wash it repeatedly with ethanol and deionized water. Dry the product under vacuum at 60℃ for 8 hours to obtain yellow indium oxide nanorods. Step 4: Wrap the yellow indium oxide nanorods prepared in Step 3 with aluminum foil and place them in a ceramic boat. Calcinate them in a tube furnace at 450-550℃ under a flowing N2 atmosphere for 2-4 hours. Transform them into a tubular structure through Oswald sintering to obtain black hollow indium oxide nanotubes. Step 5: Place 0.10 g of the hollow indium oxide nanotubes prepared in Step 4 into a flask, add 10 mL of pyridine solution of cuprous chloride, evacuate the flask to form a negative pressure environment inside the flask and maintain it for 6-10 h, centrifuge and pour off the supernatant, and dry the lower layer of indium oxide nanotubes containing pyridine copper complex for 8 h for later use. Step 6: Fill a conical flask wrapped with tin foil with 10 mL of dichloromethane solution, add 0.01-0.05 g of hexaethynylbenzene, add the above-mentioned indium oxide nanotubes containing pyridine copper complex, evacuate under argon atmosphere for 24-30 h, centrifuge, wash repeatedly with ethanol and deionized water, wash three times with ethanol and three times with deionized water respectively, and dry to obtain the graphdiyne / indium oxide nanotube photocatalyst.

[0017] In step two, the molar ratio of indium nitrate pentahydrate to 2-aminoterephthalic acid is 1:1-1:3, and the molar concentration of indium nitrate pentahydrate in N,N-dimethylformamide is 0.077 mol / L. In step two, the concentration of oleylamine in N,N-dimethylformamide is 0.015 mol / L, and the concentration of oleic acid in N,N-dimethylformamide is 0.008 mol / L. In step six, the concentration of hexaethynylbenzene in dichloromethane is 0.1-0.3 mmol / L. In step three, the high-pressure reactor heating process is a programmed temperature rise, with a heating rate of 8-15℃ / min. In step four, the tubular furnace calcination process is a programmed temperature rise, with a heating rate of 3-5℃ / min. In step five or six, the reaction flask is evacuated to create a negative pressure, with a vacuum degree of -20 to -40 MPa. In step five, the concentration of cuprous chloride in pyridine is 0.25-0.5 mol / L; after the reaction, crisscrossing graphdiyne layers grow on the inner and outer surfaces of the indium oxide nanotubes. The specific surface area of ​​the prepared graphdiyne-coated hollow indium oxide nanocomposite material is measured to be 86.96-92.76 m². 2 ·g -1 The band gap is 3.45 eV, and the work function of graphyne / indium oxide ranges from 4.38 eV to 6.01 eV.

[0018] Example 1 A method for preparing a graphdiyne / indium oxide nanotube photocatalyst includes the following steps: Step 1: Take 0.60g of indium nitrate pentahydrate and 0.23g of 2-aminoterephthalic acid, dissolve them in 20 mL of N,N-dimethylformamide, and disperse them under ultrasonication to obtain a uniform suspension; Step 2: Add oleylamine and oleic acid to the suspension prepared in Step 1, and stir at room temperature for 2.5 h to obtain a reddish-brown mixed solution; Step 3: Transfer the mixed solution prepared in Step 2 to a high-pressure reactor and maintain it at a pressure of 100 MPa and a temperature of 125℃ for 5-8 hours. After the reaction is completed, cool the solution to room temperature, filter it under vacuum, and wash it repeatedly with ethanol and deionized water. Dry the product under vacuum at 60℃ for 8 hours to obtain yellow indium oxide nanorods. Step 4: Wrap the yellow indium oxide nanorods prepared in Step 3 with aluminum foil and place them in a ceramic boat. Calcinate them in a tube furnace at 460℃ under a flowing N2 atmosphere for 2 hours. Transform them into a tubular structure through Oswald sintering to obtain black hollow indium oxide nanotubes. Step 5: Place 0.10 g of the hollow indium oxide nanotubes prepared in Step 4 into a flask, add 10 mL of pyridine solution of cuprous chloride, evacuate the flask to form a negative pressure environment inside the flask and keep it for 6 h, centrifuge and pour off the supernatant, and dry the lower layer of indium oxide nanotubes containing pyridine copper complex for 8 h for later use. Step 6: Fill a conical flask wrapped with tin foil with 10 mL of dichloromethane solution, add 0.01 g of hexaethynylbenzene, add the above-mentioned indium oxide nanotubes containing pyridine copper complex, evacuate under argon atmosphere for 24 h, centrifuge, wash repeatedly with ethanol and deionized water, wash three times with ethanol and three times with deionized water respectively, and dry to obtain the graphdiyne / indium oxide nanotube photocatalyst.

[0019] In step two, the molar ratio of indium nitrate pentahydrate to 2-aminoterephthalic acid is 1:1, and the molar concentration of indium nitrate pentahydrate in N,N-dimethylformamide is 0.077 mol / L. In step two, the concentration of oleylamine in N,N-dimethylformamide is 0.015 mol / L, and the concentration of oleic acid in N,N-dimethylformamide is 0.008 mol / L. In step six, the concentration of hexaethynylbenzene in dichloromethane is 0.1-0.3 mmol / L. In step three, the high-pressure reactor heating process is programmed with a heating rate of 8°C / min. In step four, the tubular furnace calcination process is programmed with a heating rate of 3°C / min. In step five or six, the reaction flask is evacuated to create a negative pressure of -20 MPa. In step five, the concentration of cuprous chloride in pyridine is 0.25 mol / L; after the reaction, crisscrossing graphyne layers grow on the inner and outer surfaces of the indium oxide nanotubes. The specific surface area of ​​the prepared graphdiyne-coated hollow indium oxide nanocomposite material was measured to be 86.96 m². 2 ·g -1 The band gap is 3.45 eV, and the work functions of graphyne / indium oxide are 4.42 eV.

[0020] Example 2 A method for preparing a graphdiyne / indium oxide nanotube photocatalyst includes the following steps: Step 1: Take 0.60g of indium nitrate pentahydrate and 0.23g of 2-aminoterephthalic acid, dissolve them in 20 mL of N,N-dimethylformamide, and disperse them under ultrasonication to obtain a uniform suspension; Step 2: Add oleylamine and oleic acid to the suspension prepared in Step 1, and stir at room temperature for 2.5 h to obtain a reddish-brown mixed solution; Step 3: Transfer the mixed solution prepared in Step 2 to a high-pressure reactor and maintain it at a pressure of 200 MPa and a temperature of 250℃ for 8 hours. After the reaction is completed, cool the solution to room temperature, filter it under vacuum, and wash it repeatedly with ethanol and deionized water. Dry the product under vacuum at 60℃ for 8 hours to obtain yellow indium oxide nanorods. Step 4: Wrap the yellow indium oxide nanorods prepared in Step 3 with aluminum foil and place them in a ceramic boat. Calcinate them in a tube furnace at 550°C under a flowing N2 atmosphere for 4 hours. Transform them into a tubular structure through Oswald sintering to obtain black hollow indium oxide nanotubes. Step 5: Place 0.10 g of the hollow indium oxide nanotubes prepared in Step 4 into a flask, add 10 mL of pyridine solution of cuprous chloride, evacuate the flask to form a negative pressure environment inside the flask and keep it for 10 h, centrifuge and pour off the supernatant, and dry the lower layer of indium oxide nanotubes containing pyridine copper complex for 8 h for later use. Step 6: Fill a conical flask wrapped with tin foil with 10 mL of dichloromethane solution, add 0.05 g of hexaethynylbenzene, add the above-mentioned indium oxide nanotubes containing pyridine copper complex, evacuate under argon atmosphere for 30 h, centrifuge, wash repeatedly with ethanol and deionized water, wash three times with ethanol and three times with deionized water respectively, and dry to obtain the graphdiyne / indium oxide nanotube photocatalyst.

[0021] In step two, the molar ratio of indium nitrate pentahydrate to 2-aminoterephthalic acid is 1:3, and the molar concentration of indium nitrate pentahydrate in N,N-dimethylformamide is 0.077 mol / L. In step two, the concentration of oleylamine in N,N-dimethylformamide is 0.015 mol / L, and the concentration of oleic acid in N,N-dimethylformamide is 0.008 mol / L. In step six, the concentration of hexaethynylbenzene in dichloromethane is 0.3 mmol / L. In step three, the high-pressure reactor heating process is programmed with a heating rate of 15 °C / min. In step four, the tubular furnace calcination process is programmed with a heating rate of 5 °C / min. In step five or six, the reaction flask is evacuated to create a negative pressure of -40 MPa. In step five, the concentration of cuprous chloride in pyridine is 0.5 mol / L; after the reaction, crisscrossing graphyne layers grow on the inner and outer surfaces of the indium oxide nanotubes. The specific surface area of ​​the prepared graphdiyne-coated hollow indium oxide nanocomposite material was measured to be 92.76 m². 2 ·g -1 The band gap is 3.45 eV, and the work function of graphyne / indium oxide is 5.99 eV.

[0022] Example 3 A method for preparing a graphdiyne / indium oxide nanotube photocatalyst includes the following steps: Step 1: Take 0.60g of indium nitrate pentahydrate and 0.23g of 2-aminoterephthalic acid, dissolve them in 20 mL of N,N-dimethylformamide, and disperse them under ultrasonication to obtain a uniform suspension; Step 2: Add oleylamine and oleic acid to the suspension prepared in Step 1, and stir at room temperature for 2.5 h to obtain a reddish-brown mixed solution; Step 3: Transfer the mixed solution prepared in Step 2 to a high-pressure reactor and maintain it at a pressure of 150 MPa and a temperature of 180℃ for 8 hours. After the reaction is completed, cool the solution to room temperature, filter it under vacuum, and wash it repeatedly with ethanol and deionized water. Dry the product under vacuum at 60℃ for 8 hours to obtain yellow indium oxide nanorods. Step 4: Wrap the yellow indium oxide nanorods prepared in Step 3 with aluminum foil and place them in a ceramic boat. Calcinate them in a tube furnace at 500℃ under a flowing N2 atmosphere for 4 hours. Transform them into a tubular structure through Oswald sintering to obtain black hollow indium oxide nanotubes. Step 5: Place 0.10 g of the hollow indium oxide nanotubes prepared in Step 4 into a flask, add 10 mL of pyridine solution of cuprous chloride, evacuate the flask to form a negative pressure environment inside the flask and keep it for 8 h, centrifuge and pour off the supernatant, and dry the lower layer of indium oxide nanotubes containing pyridine copper complex for 8 h for later use. Step 6: Fill a conical flask wrapped with tin foil with 10 mL of dichloromethane solution, add 0.05 g of hexaethynylbenzene, add the above-mentioned indium oxide nanotubes containing pyridine copper complex, evacuate under argon atmosphere for 30 h, centrifuge, wash repeatedly with ethanol and deionized water, wash three times with ethanol and three times with deionized water respectively, and dry to obtain the graphdiyne / indium oxide nanotube photocatalyst.

[0023] In step two, the molar ratio of indium nitrate pentahydrate to 2-aminoterephthalic acid is 1:3, and the molar concentration of indium nitrate pentahydrate in N,N-dimethylformamide is 0.077 mol / L. In step two, the concentration of oleylamine in N,N-dimethylformamide is 0.015 mol / L, and the concentration of oleic acid in N,N-dimethylformamide is 0.008 mol / L. In step six, the concentration of hexaethynylbenzene in dichloromethane is 0.3 mmol / L. In step three, the high-pressure reactor heating process is programmed with a heating rate of 10 °C / min. In step four, the tubular furnace calcination process is programmed with a heating rate of 4 °C / min. In step five or six, the reaction flask is evacuated to create a negative pressure of -30 MPa. In step five, the concentration of cuprous chloride in pyridine is 0.5 mol / L; after the reaction, crisscrossing graphyne layers grow on the inner and outer surfaces of the indium oxide nanotubes. The specific surface area of ​​the prepared graphdiyne-coated hollow indium oxide nanocomposite material was measured to be 88.56 m². 2 ·g -1 The band gap is 3.45 eV, and the work function of graphyne / indium oxide is 5.12 eV.

[0024] Examples 1, 2, and 3 demonstrate that the prepared graphyne-coated hollow indium oxide nanocomposite material exhibits significantly superior specific surface area and graphyne / indium oxide work function compared to existing technologies. Furthermore, comparisons in Examples 2 and 3 show that, under the same formulation, increasing the pressure and temperature of the high-pressure reactor in step 3, increasing the calcination time and temperature in the tubular furnace under flowing N2 atmosphere in step 4, increasing the holding time after creating a negative pressure environment in the flask in step 5, and increasing the holding time after vacuuming under argon conditions in step 6 can further improve the specific surface area and graphyne / indium oxide work function of the graphyne-coated hollow indium oxide nanocomposite material.

[0025] The technical effects of the present invention will be explained in detail with reference to the accompanying drawings: 1. XRD Analysis Figure 1 The XRD patterns revealed the chemical composition and crystal structure of indium oxide powder, carbon-coated hollow indium oxide, and graphyne-coated carbon-coated hollow indium oxide nanocomposites. The diffraction peaks at 21.5°, 30.6°, 35.5°, 51.0°, and 60.7° were highly consistent with the (211), (222), (400), (440), and (622) crystal planes of indium oxide, indicating that cubic indium oxide was the final nanomaterial. All peaks were observed in In₂O₃ / C / GDY. The graphyne-coated carbon-coated hollow manganese ferrite nanocomposites, after graphyne loading, exhibited relatively obvious graphyne-carbon characteristic peaks, indicating successful graphyne loading. The XRD patterns showed that a highly crystalline heterostructure was successfully synthesized, and the composite of carbon and graphyne did not affect the crystal structure of indium oxide.

[0026] 2. Raman analysis Figure 2 This section presents the Raman spectra of nanocomposites consisting of indium oxide powder, carbon-coated hollow indium oxide, and graphyne-coated carbon-coated hollow indium oxide. Raman spectroscopy is more sensitive to carbon materials and can be used to study the chemical structure of composite materials. The Raman spectroscopy indicates the presence of partially graphitized carbon in In₂O₃ / C, as the D band intensity is weaker than the G band. Graphitized carbon can promote electron transfer, leading to enhanced photocatalytic reactions. GDY exhibits intensity at 1597 and 1377 cm⁻¹. -1 The two main bands centered on GDY are attributed to the typical G-band and D-band, which originate from acetylene bonds and conjugated diyne chains, respectively. Characteristic D-bands attributable to GDY were also observed in the composite material, confirming the presence of GDY. It should be noted that, compared to pure GDY, the D-bands and G-bands of GDY in the composite material show a slight shift to lower wavenumbers, indicating a strong interaction between GDY and In₂O₃ in the composite material.

[0027] 3. SEM Analysis Figure 3Scanning electron microscopy (SEM) images successfully confirmed the solid rods of In-MOF (Figure ①), showing that the average diameter and length of the indium oxide solid rods were 200±75 nm and 25000±300 nm, respectively (Figure ②). Figure ③ shows the hollow structure of In₂O₃ / GDY, the hollowness originating from calcination treatment. This is because after the indium oxide nanorods were wrapped in a ceramic boat with aluminum foil, a solid solution was formed during the holding process in a flowing N₂ atmosphere and a tube furnace, which was then transformed into a tubular structure through Oswald sintering. After undergoing a hydrothermal process, it was clearly found that the interior and exterior of the In₂O₃ / GDY were completely covered by a thin layer of GDY in a regular sequence, thus preparing the target indium oxide / graphyne heterostructure. Figure ④ shows that the graphyne prepared in this work has a thickness of less than 50 nm, combining flexibility and continuity, making it a novel material in the carbon family. Compared to indium oxide nanorods, the outer surface of the carbon-coated hollow manganese ferrite nanocomposite material with graphyne coating exhibits a large number of crisscrossing sheet-like materials, which is strong evidence of the successful loading of graphyne onto the carbon-coated hollow indium oxide surface.

[0028] 4. Photocatalytic performance test Testing instruments: The PCX-50C Discover multi-channel photocatalytic reaction system (manufactured by Beijing Pofilai) was used; the product concentration was detected using a GC9790plus gas chromatograph (manufactured by Zhejiang Fuli). This gas chromatograph features a detection system consisting of FID and TCD, as well as a temperature control device.

[0029] Test Method: The photocatalytic performance of the synthesized catalyst was evaluated by reducing CO2 under visible and near-infrared light irradiation, with methane as the main product. A 300W Xe lamp (Zhongjiao Jinyuan, Cell-HXF 300) equipped with 420nm and 760nm cut filters was used as the light source. 20mg of photocatalyst was placed in 30ml of deionized water, along with 5mL of acetonitrile and 5mL of triethanolamine. Before irradiation, the mixture was continuously stirred in the dark for 30min to reach adsorption and desorption equilibrium. Then, a gas mixture (H2 / CO2 = 3 / 1, 33000 cm⁻¹) was added. 3 h -1 g cat -1 Up to 3 MPa. Surface gas products are measured every hour.

[0030] The calculation formula is as follows: In the formula, n represents the number of moles, A represents the peak area, and f represents the calibration parameter (f CO2 =1), M CH3OH Indicates molar mass.

[0031] Figure 4The curves were designed to verify the photocatalytic activity of each sample. Multiple photocatalytic experiments were conducted using CO2 reduction. The graphs show the change in CH4 production from CO2 reduction as a product of different samples under simulated sunlight irradiation over time. As can be seen from the graphs, after 6 hours of irradiation, the indium oxide / graphyne hollow nanotube photocatalytic reduction of CO2 produced the highest CH4 yield, calculated to be approximately 39.6 μmol / g.

Claims

1. A method for preparing a graphdiyne / indium oxide nanotube photocatalyst, characterized in that: Includes the following steps: Step 1: Take 0.60g of indium nitrate pentahydrate and 0.23g of 2-aminoterephthalic acid, dissolve them in 20 mL of N,N-dimethylformamide, and obtain a uniform suspension by ultrasonic dispersion; Step 2: Add oleylamine and oleic acid to the suspension prepared in Step 1, and stir at room temperature for 2.5 h to obtain a reddish-brown mixed solution; Step 3: Transfer the mixed solution prepared in Step 2 to a high-pressure reactor and maintain it at a pressure of 100-200 MPa and a temperature of 125-250℃ for 5-8 hours. After the reaction is completed, cool the solution to room temperature, filter it under vacuum, and wash it repeatedly with ethanol and deionized water. Dry the product under vacuum at 60℃ for 8 hours to obtain yellow indium oxide nanorods. Step 4: Wrap the yellow indium oxide nanorods prepared in Step 3 in a ceramic boat with aluminum foil and place it in a tube furnace. Heat the furnace to 450-550℃ in a flowing N2 atmosphere and hold for 2-4 hours. The resulting structure is transformed into a tubular structure by Oswald ripening sintering, yielding black hollow indium oxide nanotubes. Step 5: Place 0.10 g of the hollow indium oxide nanotubes prepared in Step 4 into a flask, add 10 mL of pyridine solution of cuprous chloride, evacuate the flask to form a negative pressure environment inside the flask and maintain it for 6-10 h, centrifuge and pour off the supernatant, and dry the lower layer of indium oxide nanotubes containing pyridine copper complex for 8 h for later use. Step 6: Fill a conical flask wrapped with tin foil with 10 mL of dichloromethane solution, add 0.01-0.05 g of hexaethynylbenzene, add the above-mentioned indium oxide nanotubes containing pyridine copper complex, evacuate under argon atmosphere for 24-30 h, centrifuge, wash repeatedly with ethanol and deionized water, wash three times with ethanol and three times with deionized water respectively, and dry to obtain the graphdiyne / indium oxide nanotube photocatalyst.

2. The method for preparing the graphdiyne / indium oxide nanocatalyst according to claim 1, characterized in that: In step two, the molar ratio of indium nitrate pentahydrate to 2-aminoterephthalic acid is 1:1 to 1:3, and the molar concentration of indium nitrate pentahydrate in N,N-dimethylformamide is 0.077 mol / L.

3. The method for preparing the graphdiyne / indium oxide nanocatalyst according to claim 1, characterized in that: In step two, the concentration of oleylamine in N,N-dimethylformamide is 0.015 mol / L, and the concentration of oleic acid in N,N-dimethylformamide is 0.008 mol / L.

4. The method for preparing the graphdiyne / indium oxide nanocatalyst according to claim 1 or 2, characterized in that: In step six, the concentration of hexaethynylbenzene in dichloromethane is 0.1-0.3 mmol / L.

5. The method for preparing the graphdiyne / indium oxide nanocatalyst according to claim 1, characterized in that: The heating process of the high-pressure reactor in step three is a programmed temperature rise, with a heating rate of 8-15℃ / min.

6. The method for preparing the graphdiyne / indium oxide nanocatalyst according to claim 1, characterized in that: In step four, the tubular furnace calcination process is a programmed temperature rise, with a heating rate of 3-5℃ / min.

7. The method for preparing the graphdiyne / indium oxide nanocatalyst according to claim 1, characterized in that: In step five or six, the reaction flask is evacuated to create a negative pressure, with a vacuum degree of -20 to -40 MPa.

8. The method for preparing the graphdiyne / indium oxide nanocatalyst according to claim 1, characterized in that: In step five, the concentration of cuprous chloride in pyridine is 0.25-0.5 mol / L; after the reaction, crisscrossing graphdiyne layers grow on the inner and outer surfaces of the indium oxide nanotubes; the specific surface area of ​​the prepared graphdiyne-coated hollow indium oxide nanocomposite material is 86.96-92.76 m². 2 ·g -1 The band gap is 3.45 eV, and the work function of graphyne / indium oxide ranges from 4.38 eV to 6.01 eV.

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