Metal-oxygen vacancy double-site synergistic catalyst as well as preparation method and application thereof

Abstract

The invention discloses a metal-oxygen vacancy double-site synergistic photocatalyst, a preparation method and application of the metal-oxygen vacancy double-site synergistic photocatalyst in driving ammonia and methanol to construct a carbon-nitrogen bond. The preparation method of the photocatalyst comprises the following steps: (1) dispersing a catalyst into deionized water; (2) preparing a solution A; (3) adding a proper amount of the solution A into the catalyst dispersion liquid, and fully stirring to obtain a yellow precursor solution; (4) drying the obtained precursor solution in a drying oven to obtain yellow precursor powder; and (5) carrying out reduction heat treatment on the yellow precursor powder to obtain the metal-oxygen vacancy double-site synergistic photocatalyst. The metal-oxygen vacancy double-site synergistic photocatalyst is developed and used for driving ammonia and methanol to mildly generate formamide, and the strategy can reduce energy consumption, improve the product synthesis efficiency, turn waste into wealth and achieve high-value conversion.

Description

Technical Field

[0001] The present invention belongs to the field of photocatalytic synthesis of carbon-nitrogen compounds, and specifically relates to a metal-oxygen vacancy dual-site synergistic photocatalyst, a preparation method and its application in driving ammonia and methanol to construct a carbon-nitrogen bond. Background Art

[0002] Carbon and nitrogen compounds such as amides and amines play a vital role in the production of bulk chemicals, fertilizers and pharmaceuticals, and have become an indispensable basic chemical raw material for social development. In particular, the demand for formamide is continuing to increase in the fields of pharmaceutical processes, polymers and plastic applications. However, traditional formamide synthesis mainly uses fossil fuel-derived carbon monoxide and ammonia as reaction raw materials, and requires high temperature and high pressure conditions. This leads to the consumption of a large amount of energy and the release of a large amount of greenhouse gases during its production process, posing a threat to environmental and economic sustainable development. In recent years, photocatalytic technology has great potential in the high-value conversion of small molecules due to its environmental friendliness and mild reaction conditions. Since the interaction between gaseous carbon sources and nitrogen sources is usually weak, side reactions mainly occur between gaseous reactants, thereby reducing the synthesis yield and selectivity of carbon and nitrogen compounds. Therefore, increasing the solubility of carbon and nitrogen sources in water will strengthen the interaction between carbon-nitrogen intermediates, thereby promoting the construction of carbon-nitrogen bonds. It is worth noting that ammonia can be dehydrogenated in one step to produce active nitrogen species and is a good nitrogen source. At the same time, methanol can easily undergo oxidation reactions to generate a variety of carbon intermediates that can interact with nitrogen active species, which can solve the problem of weak interaction between carbon and nitrogen species. Therefore, efficient construction of carbon-nitrogen bonds by light-driven ammonia and methanol will provide a powerful technology for solving energy and environmental problems and lay the foundation for the mild synthesis of fine chemicals.

[0003] In addition, the interaction between reaction intermediates is closely related to the active sites of the catalyst. If a photocatalyst that can selectively activate the reactant molecules and has mild redox ability can be designed, the side reactions can be reduced and the efficient construction of carbon-nitrogen bonds can be achieved. Therefore, it is necessary to design a metal-oxygen vacancy dual-site synergistic photocatalyst for the efficient synthesis of formamide from ammonia and methanol. Summary of the invention

[0004] In order to solve the problems of low efficiency and selectivity in the existing photocatalytic synthesis of formamide, the present invention provides a metal-oxygen vacancy dual-site synergistic photocatalyst, a preparation method and its application in driving ammonia and methanol to construct a carbon-nitrogen bond, aiming to strengthen the coupling of carbon-nitrogen intermediates and improve the efficiency of formamide synthesis. This technology can also provide a theoretical basis for the synthesis of other fine chemicals.

[0005] The scheme adopted by the present invention is as follows: A method for preparing a metal-oxygen vacancy dual-site synergistic photocatalyst comprises the following steps: (1) Disperse the catalyst in deionized water.

[0006] (2) Prepare solution A.

[0007] (3) Add an appropriate amount of solution A to the catalyst dispersion and stir thoroughly to obtain a yellow precursor solution.

[0008] (4) The obtained precursor solution is placed in an oven for drying to obtain a yellow precursor powder.

[0009] (5) The yellow precursor powder was subjected to reduction heat treatment to obtain a metal-oxygen vacancy dual-site synergistic photocatalyst.

[0010] Furthermore, in step (1), 0.1-0.5 g of titanium dioxide powder is dispersed in 10-20 mL of deionized water.

[0011] Furthermore, the composition of solution A in step (2) is: 1.00 g chloroauric acid (HAuCl4·4H2O) and 100 mL deionized water.

[0012] Further, 0.1-0.8 mL of solution A was added to the catalyst dispersion and stirred at room temperature for 20-40 min to obtain a yellow precursor solution.

[0013] Furthermore, in step (4), the yellow precursor solution is placed in an oven, the temperature is set to 100-110° C., and the oven is kept warm and dried for 1-2 h to obtain a yellow precursor powder.

[0014] Furthermore, the reduction heat treatment of the yellow precursor powder in step (5) is performed by heating the yellow precursor powder to 400 °C at a heating rate of 2 °C / min in a 5% H2 / Ar atmosphere, keeping the temperature for 2 h, and then cooling the yellow precursor powder to obtain a purple gold-oxygen vacancy dual-site modified titanium dioxide (Au-TiO2-V O ) photocatalyst.

[0015] The present invention also provides an application of a metal-oxygen vacancy dual-site synergistic photocatalyst to drive ammonia and methanol to construct a carbon-nitrogen bond, comprising the following steps: a. Metal-oxygen vacancy dual-site synergistic photocatalyst is used as a heterogeneous catalyst to drive ammonia and methanol to construct a carbon-nitrogen bond system, and the solvent is water.

[0016] b. Dissolve the photocatalyst in water, perform ultrasonic dispersion, add ammonia and methanol as reactants, perform photocatalytic co-oxidation reaction to synthesize formamide.

[0017] c. The activity of photocatalytic co-oxidation reaction to synthesize formamide was regulated by preparing metal-oxygen vacancy dual-site synergistic photocatalysts with different metal contents.

[0018] d. The activity of photocatalytic co-oxidation reaction for synthesizing formamide was regulated by adjusting the concentration ratio of ammonia and methanol.

[0019] e. The activity of the photocatalytic co-oxidation reaction to synthesize formamide was regulated by adjusting the ratio of oxygen to argon.

[0020] Furthermore, in step (b), the photocatalyst content is 5-20 mg, the ammonia concentration is 0-5000 mg / L, the methanol concentration is 0-5000 mg / L, and the volume of deionized water is 30 mL.

[0021] Furthermore, in step (c), 0.2 g of titanium dioxide was weighed, and the mass fractions of gold content relative to titanium dioxide were 0.5 wt%, 1.0 wt%, 2.0 wt% and 4.0 wt%, respectively.

[0022] Furthermore, in step (d), the methanol concentration is set to 5000 mg / L, and the ratio of the ammonia concentration to the methanol concentration is adjusted to 1:1, 1:1.5, 1:2, 1:2.5, and 1:3, respectively.

[0023] Furthermore, in step (e), the ratio of oxygen to argon is 0-100%.

[0024] Compared with the currently widely used synthesis prior art, the innovation of the present invention lies not only in the originality of its design concept, but also in the significant technical advantages it has demonstrated in practical applications. These advantages have profoundly promoted the technological progress and industrial upgrading in the field of formamide synthesis, which are specifically reflected in the following aspects: (1) Innovative photocatalyst design and improved reaction efficiency.

[0025] The core of the present invention is to cleverly design a photocatalyst that integrates the synergistic effect of metal and oxygen vacancy double sites - Au-TiO2-V O This design strategy has achieved a major breakthrough in the performance of traditional photocatalytic materials. By precisely controlling the loading amount of gold (Au) on the TiO2 substrate and introducing oxygen vacancies (V O), we constructed a highly synergistic catalytic interface. This interface not only significantly enhances the catalyst's adsorption capacity for ammonia and methanol molecules, allowing the reactants to more effectively accumulate on the catalyst surface, but also greatly promotes the activation process of the reactants and reduces the activation energy of the reaction. In addition, by systematically optimizing the feed concentrations of ammonia and methanol and precisely controlling the ratio of oxygen to argon in the reaction atmosphere, the present invention further improves the synthesis efficiency of formamide and achieves a double leap in reaction rate and yield. The implementation of this series of strategies not only demonstrates the present invention's outstanding ability in improving reaction efficiency, but also lays a solid foundation for its economy in industrial applications.

[0026] (2) Innovation in the synthesis technology of carbon-nitrogen compounds under mild conditions.

[0027] Driven by the concepts of green chemistry and sustainable development, the present invention has developed a new synthesis pathway for carbon and nitrogen compounds under mild conditions, especially for the synthesis of formamide. This technological breakthrough is of milestone significance. It abandons the use of high temperature, high pressure or harmful raw materials that may be involved in traditional synthesis methods, and instead adopts a more energy-saving, environmentally friendly and easy-to-operate strategy. The successful application of this new technology not only greatly reduces the energy consumption and emissions in the synthesis process, but also significantly improves the safety and sustainability of the production process. More importantly, the excellent and stable photocatalyst provided by the present invention not only accelerates the synthesis rate of formamide and improves the selectivity of the product, but also opens up a new path for the mild and controllable synthesis of other fine chemicals. The promotion and application of this technology is expected to lead the field of synthetic chemistry to a greener, more efficient and precise direction, and contribute important forces to the transformation and upgrading of the chemical industry worldwide. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for describing the embodiments are briefly introduced below.

[0029] Figure 1 The gold-modified titanium dioxide photocatalyst (Au-TiO2) and the oxygen vacancy-modified titanium dioxide photocatalyst (TiO2-V O ) and gold-oxygen vacancy modified titanium dioxide photocatalyst (Au-TiO2-V O )’s X-ray diffraction pattern.

[0030] Figure 2 The Au-TiO2-V prepared in Example 1 of the present invention O Scanning electron microscopy and transmission electron microscopy images of Figure 2 (a) is a scanning electron microscope image. Figure 2 (b) is a transmission electron microscope image.

[0031] Figure 3 The Au-TiO2-V prepared in Example 1 of the present invention O Gold particle size distribution diagram.

[0032] Figure 4 The Au-TiO2 and TiO2-V prepared in Example 1 of the present invention are O and Au-TiO2-V O X-ray photoelectron spectrum of titanium in the photocatalyst.

[0033] Figure 5 The Au-TiO2 and TiO2-V prepared in Example 1 of the present invention are O and Au-TiO2-V O Electron paramagnetic resonance spectrum of the photocatalyst.

[0034] Figure 6 The present invention is Au-TiO2, TiO2-V O and Au-TiO2-V O UV-visible diffuse reflectance spectrum of the photocatalyst.

[0035] Figure 7 The present invention is Au-TiO2, TiO2-V O and Au-TiO2-V O Comparison of photocatalyst-driven activity of ammonia and methanol in the synthesis of formamide.

[0036] Figure 8 The Au-TiO2-V prepared by the present invention with different gold contents in a system containing 2500 mg / L ammonia and 5000 mg / L methanol, 10 mg O Comparative activity of photocatalysts (0.5 wt%, 1.0 wt%, 2.0 wt%, 4.0 wt%) in driving the synthesis of formamide from ammonia and methanol.

[0037] Fig. 9 The present invention is 2.0 wt% Au-TiO2-V O Comparison of the activity of the photocatalyst in driving the synthesis of formamide from ammonia and methanol under conditions of different concentration ratios of ammonia and methanol (1:1, 1:1.5, 1:2, 1:2.5, 1:3) when the methanol concentration was 5000 mg / L.

[0038] Fig.10 The present invention is a 2.0 wt% Au-TiO2-V prepared in a system containing 2500 mg / L ammonia and 5000 mg / L methanol. OComparison of the activity of photocatalysts in driving the synthesis of formamide from ammonia and methanol in atmospheres with different oxygen concentrations (0%, 20%, 50%, 80%, 100%). DETAILED DESCRIPTION

[0039] The present invention is described in detail below in conjunction with specific embodiments.

[0040] Example 1 is a fixed reactant concentration, Au-TiO2, TiO2-V O and Au-TiO2-V O Comparison of the activity of photocatalyst driven ammonia and methanol to formamide, Example 2-3 is a fixed reaction atmosphere, changing the gold content of Au-TiO2-V O Photocatalysts, and Au-TiO2-V O Comparison of the activity of photocatalysts for synthesizing formamide at different concentration ratios of ammonia and methanol; Example 4 is the use of Au-TiO2-V O Comparison of the activity of photocatalysts to synthesize formamide by driving ammonia and methanol with changing reaction atmosphere.

[0041] Example 1.

[0042] (1) Au-TiO2-V O The method for preparing a photocatalyst comprises the following steps: Weigh 0.2 g of titanium dioxide and dissolve it in 10 mL of deionized water. Prepare solution A by dissolving 1.00 g of chloroauric acid in 100 mL of deionized water and store it in a refrigerator. Take 0.4 mL of solution A and add it to the catalyst dispersion, stir at room temperature for 30 min to obtain a yellow precursor solution. Place the evenly stirred yellow precursor solution in an oven, keep it warm and dry at 110 °C for 2 h to obtain a yellow precursor powder. Heat the obtained yellow precursor powder to 400 °C at a heating rate of 2 °C / min in a 5% H2 / Ar atmosphere, keep it warm for 2 h, and then cool it to room temperature to obtain a purple 2.0 wt% Au-TiO2-V O Photocatalyst.

[0043] (2) A method for preparing an Au-TiO2 photocatalyst comprises the following steps: Weigh 0.2 g of titanium dioxide and dissolve it in 10 mL of deionized water. Prepare solution A by dissolving 1.00 g of chloroauric acid in 100 mL of deionized water and store it in a refrigerator. Take 0.4 mL of solution A and add it to the catalyst dispersion, stir at room temperature for 30 min to obtain a yellow precursor solution. Place the stirred yellow precursor solution in an oven and keep it warm and dry at 110 °C for 2 h to obtain a yellow precursor powder. Heat the obtained yellow precursor powder to 400 °C at a heating rate of 2 °C / min in an air atmosphere, keep it warm for 2 h, and then cool it to room temperature to obtain a lavender 2.0 wt% Au-TiO2 photocatalyst.

[0044] (3) A TiO2-V O The method for preparing a photocatalyst comprises the following steps: Weigh 0.2 g of titanium dioxide into a mortar, add 0.1 g of sodium borohydride, and grind evenly. Put the mixed white solid into a 50 mL covered crucible, heat it to 350 °C at a rate of 2 °C / min in an air atmosphere, keep it warm for 1 h, and then cool it to room temperature to obtain a blue-gray TiO2-V O Photocatalyst.

[0045] The Au-TiO2 and TiO2-V prepared in Example 1 O and Au-TiO2-V O The photocatalyst was subjected to X-ray diffraction (XRD) analysis. The results showed that the Au-TiO2 and TiO2-V prepared in Example 1 O and Au-TiO2-V O The photocatalysts are indexed as standard PDF # 21-1272 and 21-1276, corresponding to anatase and rutile mixed TiO2, respectively. Gold nanoparticles are not shown in the XRD patterns due to the low modification content.

[0046] Scanning electron microscope (SEM) analysis revealed that the Au-TiO2-V prepared in Example 1 O The photocatalyst is spherical ( Figure 2 In addition, the results of high-resolution transmission electron microscopy (HRTEM) showed that the interplanar spacing between gold nanoparticles and TiO2 was 0.25 nm and 0.35 nm, respectively. Figure 2 (b) in Figure 2), which matches the (111) surface of gold and the (101) surface of anatase titanium dioxide, confirming that the Au-TiO2-V prepared in the present invention O The photocatalyst is anatase titanium dioxide photocatalyst dominated by gold (111) crystal plane modification.

[0047] Then, Au-TiO2-VO Photocatalyst gold nanoparticle size analysis based on HRTEM results ( Figure 3 In (a), it was found that gold nanoparticles with a size of about 4.8 nm were uniformly distributed on the titanium dioxide surface ( Figure 3 (b) in the figure.

[0048] The Au-TiO2 and TiO2-V prepared in Example 1 O and Au-TiO2-V O Perform X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) tests ( Figure 4 , Figure 5 ). Figure 4 The XPS graph shows that due to the lack of oxygen atoms, in order to maintain electrical neutrality, the metal ions must reduce their valence state, making TiO2-V O and Au-TiO2-V O The Ti 2p binding energy of Au-TiO2 moves toward the low binding energy direction; Figure 5 EPR spectrum of TiO2-V O and Au-TiO2-V O The presence of oxygen vacancies was detected in all samples. This confirms the successful preparation of gold-oxygen vacancy modified titanium dioxide photocatalyst. UV-visible diffuse reflectance spectroscopy ( Figure 6 ) revealed that gold-oxygen vacancies synergistically effectively enhanced light absorption ability.

[0049] The Au-TiO2 and TiO2-V prepared in Example 1 were used. O and Au-TiO2-V O They were used as photocatalysts for photocatalytic reaction tests. The specific process is as follows: 10 mg of photocatalyst was fully dissolved in 30 mL of deionized water, followed by the addition of 2500 mg / L ammonia and 5000 mg / L methanol as reactants, and the completely mixed solution was poured into a quartz reactor with a condensation device to keep the reaction temperature at 25 °C, and a 300 W full-spectrum xenon lamp was used to irradiate the reactor from the top for 3 h in an air atmosphere, 0.3 mL of the reaction solution was taken with a syringe every hour, the catalyst was filtered through a disposable filter, and then the formamide yield was detected by high performance liquid chromatography.

[0050] Figure 7 The unit yield of formamide shows that Au-TiO2-V O The photocatalyst exhibited excellent performance in driving the oxidation of ammonia and methanol to form formamide, compared with TiO2-V OThe photocatalyst has an 11-fold performance improvement, and compared with the Au-TiO2 photocatalyst, the performance has been improved by 2.5 times. The results show that gold-oxygen vacancies synergistically promote the photocatalytic ammonia and methanol co-oxidation reaction and the intermediate coupling process on the titanium dioxide surface, improve the synthesis efficiency of carbon and nitrogen compounds, and provide technical support for the efficient synthesis of fine chemicals.

[0051] Example 2.

[0052] Au-TiO2-V with different gold contents O The method for preparing a photocatalyst comprises the following steps: Weigh 0.2 g of titanium dioxide and dissolve it in 10 mL of deionized water. Prepare solution A, dissolve 1.00 g of chloroauric acid in 100 mL of deionized water, and store it in a refrigerator. Take 0.1 mL, 0.2 mL, 0.4 mL, and 0.8 mL of solution A and add them to the catalyst dispersion, stir at room temperature for 30 min, and obtain different yellow precursor solutions. Place the above-mentioned uniformly stirred yellow precursor solution in an oven, keep it warm and dry at 110 ℃ for 2 h to obtain a yellow precursor powder. The obtained yellow precursor powder was heated to 400 ℃ at a heating rate of 2 ℃ / min in a 5% H2 / Ar atmosphere, kept warm for 2 h, and then cooled to room temperature to obtain 0.5 wt%, 1.0 wt%, 2.0 wt%, and 4.0 wt% Au-TiO2-V of different purple colors. O Photocatalyst.

[0053] 0.5 wt% Au-TiO2-V with different gold contents prepared in Example 2 O 、1.0 wt%Au-TiO2-V O 、2.0wt%Au-TiO2-V O 、4.0 wt%Au-TiO2-V O As a photocatalyst. Take 10 mg of the photocatalyst and fully dissolve it in 30 mL of deionized water, then add 2500 mg / L ammonia and 5000 mg / L methanol as reactants, pour the completely mixed solution into a quartz reactor with a condenser to keep the reaction temperature at 25 °C, use a 300 W full-spectrum xenon lamp to irradiate the reactor from the top for 3 h in an air atmosphere, take 0.3 mL of the reaction solution every hour with a syringe, filter the catalyst through a disposable filter, and then use high performance liquid chromatography to detect the formamide yield.

[0054] Figure 8The activity comparison diagram shows that the synthesis yield of formamide and the gold content show a volcano-type law, that is, within a certain range, the synthesis efficiency of formamide increases significantly with the increase of gold content, but modifying more gold reactions will weaken the synergistic effect with oxygen vacancies and reduce the synthesis efficiency of formamide.

[0055] Example 3.

[0056] The Au-TiO2-V prepared in Example 1 O As a photocatalyst, photocatalytic reaction was carried out. Weigh 5 mg 2.0 wt% Au-TiO2-V O The photocatalyst was fully dissolved in 30 mL of deionized water, the concentration of methanol was fixed at 5000 mg / L, and the concentration ratio of ammonia to methanol was adjusted to 1:1, 1:1.5, 1:2, 1:2.5, and 1:3. The completely mixed solution was poured into a quartz reactor with a condenser to keep the reaction temperature at 25 °C. A 300 W full-spectrum xenon lamp was used to irradiate the reactor for 3 h under air atmosphere. 0.3 mL of the reaction solution was taken with a syringe every hour, the catalyst was filtered through a disposable filter, and the formamide yield was detected by high performance liquid chromatography.

[0057] Fig. 9 The formamide activity comparison chart shows that when the concentration ratio of ammonia to methanol is 1:2.5, 2.0 wt% Au-TiO2-V O The photocatalyst can carry out the maximum carbon-nitrogen coupling and generate more formamide products.

[0058] Example 4.

[0059] The Au-TiO2-V prepared in Example 1 O As a photocatalyst, photocatalytic reaction was carried out. Weigh 10 mg 2.0wt% Au-TiO2-V O Fully dissolve in 30 mL of deionized water, then add 2500 mg / L ammonia and 5000 mg / L methanol as reactants, pour the fully mixed solution into a quartz reactor with a condenser to keep the reaction temperature at 25°C, and adjust the ratio of oxygen to argon for atmosphere reaction. Vent for 10 min in 0%, 20%, 50%, 80%, and 100% oxygen atmosphere, respectively, and set the total flow rate to 50 mL / min. Use a 300 W full-spectrum xenon lamp to irradiate the reactor from the top for 3 h, take 0.3 mL of the reaction solution every hour with a syringe, filter the catalyst through a disposable filter, and then detect the formamide yield by high-performance liquid chromatography.

[0060] Fig.10The formamide activity comparison chart shows that with the increase of oxygen content, the formamide synthesis efficiency is significantly improved. This is mainly because oxygen can significantly promote the co-oxidation reaction of ammonia and methanol by consuming electrons as a reduction reaction.

Claims

1. A method for preparing a metal-oxygen vacancy dual-site synergistic photocatalyst, characterized in that: The following steps are involved: (1) Dispersing the catalyst in deionized water; (2) Prepare solution A, which consists of 1.00 g of chloroauric acid and 100 mL of deionized water; (3) Add an appropriate amount of solution A to the catalyst dispersion and stir thoroughly to obtain a yellow precursor solution; (4) The obtained precursor solution is placed in an oven for drying to obtain a yellow precursor powder; (5) The yellow precursor powder was subjected to reduction heat treatment to obtain a metal-oxygen vacancy dual-site synergistic photocatalyst.

2. The method for preparing the metal-oxygen vacancy dual-site synergistic photocatalyst according to claim 1, wherein: In step (1), 0.1-0.5 g of titanium dioxide powder was dispersed in 10-20 mL of deionized water.

3. The method for preparing the metal-oxygen vacancy dual-site synergistic photocatalyst according to claim 1, wherein: In step (3), 0.1-0.8 mL of solution A was added to the catalyst dispersion and stirred at room temperature for 20-40 min to obtain a yellow precursor solution.

4. The method for preparing the metal-oxygen vacancy dual-site synergistic photocatalyst according to claim 1, wherein: In step (4), the yellow precursor solution is placed in an oven, the temperature is set to 100-110 °C, and the oven is kept warm and dried for 1-2 hours to obtain a yellow precursor powder.

5. The method for preparing the metal-oxygen vacancy dual-site synergistic photocatalyst according to claim 1, wherein: In step (5), the yellow precursor powder is subjected to reduction heat treatment in a 5% H2 / Ar atmosphere, heated to 400°C at a heating rate of 2°C / min, kept at this temperature for 2 h, and then cooled to room temperature to obtain a purple gold-oxygen vacancy dual-site modified titanium dioxide photocatalyst.

6. A metal-oxygen vacancy dual-site synergistic photocatalyst prepared according to the method according to any one of claims 1 to 5.

7. Use of the metal-oxygen vacancy dual-site synergistic photocatalyst according to claim 6 in driving ammonia and methanol to form a carbon-nitrogen bond, characterized in that: The following steps are involved: a. A metal-oxygen vacancy dual-site synergistic photocatalyst acts as a heterogeneous catalyst to drive ammonia and methanol to construct a carbon-nitrogen bond system, with water as the solvent; b. dissolving the photocatalyst in water, performing ultrasonic dispersion, and adding ammonia and methanol as reactants to perform photocatalytic co-oxidation to synthesize formamide; c. The activity of the photocatalytic co-oxidation reaction to synthesize formamide was regulated by preparing metal-oxygen vacancy dual-site synergistic photocatalysts with different metal contents; d. The activity of the photocatalytic co-oxidation reaction to synthesize formamide was regulated by adjusting the ratio of ammonia and methanol concentrations; e. The activity of the photocatalytic co-oxidation reaction to synthesize formamide was regulated by adjusting the ratio of oxygen to argon.

8. The use of the metal-oxygen vacancy dual-site synergistic photocatalyst according to claim 7 in driving ammonia and methanol to form a carbon-nitrogen bond, characterized in that: In step (b), the photocatalyst content is 5-20 mg, the ammonia concentration is 0-5000 mg / L, the methanol concentration is 0-5000 mg / L, and the volume of deionized water is 30 mL.

9. The use of the metal-oxygen vacancy dual-site synergistic photocatalyst according to claim 7 in driving ammonia and methanol to form a carbon-nitrogen bond, characterized in that: In step (c), 0.2 g of titanium dioxide was weighed, and the mass fractions of gold relative to titanium dioxide were 0.5 wt%, 1.0 wt%, 2.0 wt%, and 4.0 wt%, respectively. In step (d), the methanol concentration was set to 5000 mg / L, and the ratios of ammonia concentration to methanol concentration were adjusted to 1:1, 1:1.5, 1:2, 1:2.5, and 1:3, respectively. In step (e), the ratio of oxygen to argon was 0-100%.

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