Oxygen-deficient titanium dioxide loaded gold-copper alloy photocatalyst as well as preparation method and application thereof

Abstract

The invention provides an oxygen-deficient titanium dioxide loaded gold-copper alloy photocatalyst as well as a preparation method and application thereof. The preparation method of the oxygen-deficient titanium dioxide loaded gold-copper alloy photocatalyst comprises the following steps: (a) dispersing polyvinylpyrrolidone, ascorbic acid, potassium bromide and titanium dioxide powder in water, stirring under a heating condition to obtain a turbid liquid, adding chloride of copper and gold, and keeping stirring to obtain a precursor turbid liquid; and (b) carrying out solid-liquid separation on the precursor suspension obtained in the step (a) to obtain a precursor material, cleaning and drying the precursor material, and carrying out high-temperature calcination in a hydrogen atmosphere to obtain the oxygen-deficient titanium dioxide-loaded gold-copper alloy photocatalyst. The oxygen-deficient titanium dioxide loaded gold-copper alloy catalyst has excellent stability, and is beneficial to catalyzing carbon dioxide to be reduced into a high-added-value product under the sunlight condition. In addition, the preparation method is simple and easy for large-scale production.

Description

Technical Field

[0001] The present invention relates to a preparation method of an oxygen-deficient titanium dioxide-supported gold-copper alloy photocatalyst, the photocatalyst and its use, belonging to the field of photocatalysis. Background Art

[0002] With the rapid development of human society and industrial level, fossil fuels are widely used, and the amount of carbon dioxide in nature has increased sharply, leading to a series of increasingly serious problems such as global warming and biodiversity destruction. Therefore, how to effectively improve the conversion and utilization ability of carbon dioxide is of great significance for maintaining the balance of the global ecological environment and is a major issue of concern to the country and society. The photocatalytic conversion technology driven by solar energy can reduce carbon dioxide to high-value hydrocarbon fuels and other chemicals under mild conditions of normal temperature and pressure, has unique advantages in environmental protection, and also has great potential in realizing green and sustainable energy development. The process of photocatalytic reduction of carbon dioxide involves the generation, separation and migration steps of photo-generated electron-hole pairs, as well as the redox reactions occurring on the catalyst surface. In order to improve the performance of photocatalytic reduction of carbon dioxide, it is necessary to precisely construct the fine structure and electron distribution of the catalyst to enhance the separation and utilization efficiency of photo-generated electron-hole pairs under sunlight and regulate the favorable reaction steps.

[0003] Although there have been relatively in-depth explorations in photocatalytic reduction of carbon dioxide at present, most of the reduction products are one-carbon products, and it is difficult to regulate the carbon-carbon coupling reaction path to generate two-carbon products with higher added value. Titanium dioxide is widely used in the field of photocatalytic carbon dioxide reduction due to its low cost, good stability, rich resources and appropriate band gap. However, the recombination of photo-generated electrons and holes in single titanium dioxide is serious, resulting in low photocatalytic efficiency. If titanium dioxide can be modified by methods such as combining vacancy engineering and loading co-catalysts, the generation and separation efficiency of photo-generated electrons can be accelerated, and the directional utilization efficiency of photo-generated electrons and holes can be improved, thereby increasing the yield and selectivity of photocatalytic carbon dioxide reduction.

[0004] CN109876843A discloses a copper alloy-modified titanium dioxide / carbon nitride heterojunction photocatalyst and a preparation method thereof. This method in-situ immobilizes copper-based alloy nanoparticles on the titanium dioxide / carbon nitride heterojunction by a deposition reduction method. The catalyst has a stable structure and shows good methane generation activity in the photocatalytic carbon dioxide reduction reaction. However, its disadvantages are that the preparation process is complex, the carrier excitation efficiency of the catalyst in the visible light region is low, and it cannot generate two-carbon products with high added value.

[0005] CN106975484A discloses a preparation method and application of an ordered mesoporous titanium dioxide-nano gold composite material. By dissolving a triblock copolymer, a water-soluble phenolic resin, a tetrabutyl titanate and concentrated hydrochloric acid in ethanol in a certain proportion, and combining a solvent evaporation-induced self-assembly process and two-step high-temperature heat treatment, a light purple ordered mesoporous titanium dioxide-nano gold composite material is obtained. The invention effectively improves the carrier excitation efficiency of the titanium dioxide catalyst under visible light. However, its disadvantages are that the added values of the generated carbon monoxide and methane products are low, and the generation efficiency is low, making it difficult to be applied on a large scale.

[0006] In the prior art, the kinetic rate of the photocatalytic reduction of carbon dioxide to synthesize acetic acid is low, the intermediate products and mechanism in the synthesis process of acetic acid are unclear, the by-products are complex, and the selectivity is low. Combining vacancy engineering and alloy effect can effectively enhance the excitation of photo-generated carriers under visible light, regulate the surface electron distribution, enhance the adsorption of substrates, adjust the reaction path, and improve the catalyst activity. Nowadays, designing the fine structure of photocatalyst materials, improving the ability of photocatalysts to be excited by light, directionally regulating reaction steps, and improving the synthesis efficiency and selectivity of high-added-value products are still the efforts of those skilled in the art. Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] Based on the problems existing in the prior art, the present invention provides a preparation method of an oxygen-deficient titanium dioxide-supported gold-copper alloy photocatalyst, an oxygen-deficient titanium dioxide-supported gold-copper alloy photocatalyst and its uses. The preparation method of the present invention is simple and feasible, and there is no secondary pollution. The oxygen-deficient titanium dioxide-supported gold-copper alloy photocatalyst of the present invention has high catalytic activity and selectivity, strong stability in recycling, and strong adaptability, which is conducive to catalytically reducing carbon dioxide to high-added-value product acetic acid with high yield and high selectivity under sunlight, and has good practical application prospects.

[0009] Solutions for Solving the Problems

[0010] The present invention provides a preparation method of an oxygen-deficient titanium dioxide-supported gold-copper alloy photocatalyst, comprising the following steps:

[0011] (a) Disperse polyvinylpyrrolidone, ascorbic acid, potassium bromide and titanium dioxide powder in water, stir to obtain a suspension under heating conditions, add chlorides of copper and gold and keep stirring to obtain a precursor suspension;

[0012] (b) Perform solid-liquid separation on the precursor suspension obtained in step (a) to obtain a precursor material, wash and dry the precursor material, and perform high-temperature calcination in a hydrogen atmosphere to obtain the oxygen-deficient titanium dioxide-supported gold-copper alloy photocatalyst.

[0013] According to the preparation method of the present invention, in step (a), the crystal form of the oxygen-deficient titanium dioxide is one or more of anatase, rutile, and brookite.

[0014] According to the preparation method of the present invention, in step (a), the mass concentration of the titanium dioxide powder in the suspension is 5-30 g / L; the mass concentration of polyvinylpyrrolidone in the suspension is 50-200 g / L; the mass concentration of ascorbic acid in the suspension is 10-50 g / L; the mass concentration of potassium bromide in the suspension is 20-50 g / L.

[0015] According to the preparation method of the present invention, in step (a), the heating is water bath heating, the temperature of the water bath heating is 20-90 °C, and the stirring time under the heating condition is 5-20 min.

[0016] According to the preparation method of the present invention, in step (a), the total molar concentration of the copper and gold chlorides in the suspension is 0.01-1 mol / L, and the holding stirring time is 2-5 h.

[0017] According to the preparation method of the present invention, in step (b), the way to clean the precursor material is one or more of centrifugation, alcohol washing, water washing, and ultrasonic cleaning, and it is washed 3-5 times; the drying temperature of the precursor material is 70-100 °C, the vacuum degree is <5 Pa, and the drying time is 1-30 h.

[0018] According to the preparation method of the present invention, in step (b), when the precursor material is calcined at high temperature, the hydrogen concentration in the hydrogen atmosphere is 5-100%, and the carrier gas is one or more of argon, helium, and nitrogen; the high-temperature calcination temperature is 300-600 °C, and the calcination time is 2-4 h.

[0019] The present invention also provides an oxygen-deficient titanium dioxide-supported gold-copper alloy photocatalyst prepared by the preparation method of the present invention.

[0020] The present invention also provides a use of the oxygen-deficient titanium dioxide-supported gold-copper alloy photocatalyst of the present invention in photocatalytic reduction of carbon dioxide to synthesize acetic acid. Among them, an aqueous solution of the photocatalyst with a concentration of 0.1-5 g / L is placed in a container filled with high-purity carbon dioxide and reacted under the full spectrum, and the reaction time is 1-4 h.

[0021] Effects of the Invention

[0022] The oxygen-deficient titanium dioxide-supported gold-copper alloy catalyst of the present invention has excellent stability, which is beneficial to efficiently catalyze the reduction of carbon dioxide to high-value products under sunlight conditions, providing an effective solution for realizing carbon cycle utilization and alleviating the greenhouse effect. In addition, the preparation method of the present invention is simple, easy to scale up production, and has good industrial application prospects. Description of the Drawings

[0023] Figure 1 High-angle annular dark-field image of the scanning transmission electron microscope of the AuCu / TiO photocatalyst prepared in Example 1; 2-x

[0024] Figure 2 Bright-field image of the transmission electron microscope of the AuCu / TiO photocatalyst prepared in Example 1, and line scan diagram of the energy spectrometer of the nanoparticles; 2-x

[0025] Figure 3 Raman spectra of the photocatalysts prepared in Example 1 and Comparative Examples 1-4;

[0026] Figure 4 X-ray diffraction (XRD) patterns of the photocatalysts prepared in Example 1 and Comparative Examples 1-4;

[0027] Figure 5 Electron paramagnetic resonance (ESR) spectra of the photocatalysts prepared in Example 1 and Comparative Examples 1-4;

[0028] Figure 6 Ultraviolet-visible absorption spectra (UV-Vis) of the photocatalysts prepared in Example 1 and Comparative Examples 1-4;

[0029] Figure 7 Activity performance test diagrams of the photocatalysts prepared in Example 1 and Comparative Examples 1-4 for photocatalytic carbon dioxide;

[0030] Figure 8 Rate test diagram of the cyclic production of acetic acid by the AuCu / TiO photocatalyst prepared in Example 1; 2-x Detailed Description of the Invention

[0031] The following will detail various exemplary embodiments, features, and aspects of the present invention. The special word "exemplary" here means "serving as an example, embodiment, or illustration". Any embodiment described as "exemplary" here does not have to be construed as superior or better than other embodiments.

[0032] In addition, for better illustration of the present invention, numerous specific details are given in the following specific embodiments. Those skilled in the art should understand that the present invention can be implemented without certain specific details. In other instances, methods, means, equipment, and steps well-known to those skilled in the art are not described in detail to highlight the gist of the present invention.

[0033] Unless otherwise specified, the units used in this specification are all international standard units, and the numerical values and numerical ranges appearing in the present invention should be understood to include the systematic errors inevitable in industrial production.

[0034] In this specification, the meaning expressed by "can" includes both the meaning of performing a certain process and not performing a certain process.

[0035] In this specification, the "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", etc. mentioned refer to the specific elements (e.g., features, structures, properties, and / or characteristics) related to the embodiment, which are included in at least one of the embodiments described herein, and may or may not exist in other embodiments. Additionally, it should be understood that the elements can be combined in various embodiments in any suitable manner.

[0036] In this specification, the numerical range expressed by "numerical value A to numerical value B" refers to the range including the endpoint numerical values A and B.

[0037] First Aspect

[0038] The present invention provides a method for preparing an oxygen-deficient titanium dioxide-supported gold-copper alloy photocatalyst, comprising the following steps:

[0039] (a) Dissolve polyvinylpyrrolidone, ascorbic acid, potassium bromide, and titanium dioxide powder in water, stir to obtain a suspension under heating conditions, add chlorides of copper and gold, and continue stirring to obtain a precursor suspension;

[0040] (b) Perform solid-liquid separation on the precursor suspension obtained in step (a) to obtain a precursor material, wash and dry the precursor material, and perform high-temperature calcination in a hydrogen atmosphere to obtain the oxygen-deficient titanium dioxide-supported gold-copper alloy photocatalyst.

[0041] Introducing AuCu alloy nanoparticles as co-catalysts into the titanium dioxide semiconductor system has the following advantages: (1) Depositing metals on the surface of titanium dioxide can form a heterostructure. Since the Fermi level of the metal is lower than that of titanium dioxide, photo-generated electrons will further transfer to the metal after migrating to the conduction band of titanium dioxide until the Fermi levels of the two are balanced. This will form a space charge layer on the surface of titanium dioxide, and then form a Schottky barrier, which helps to promote the effective separation of photo-generated electrons and holes, thereby improving the photocatalytic performance. (2) It can utilize the unique local surface plasmon resonance effect of some metals to improve the carrier excitation ability of visible light for the catalyst and enhance the utilization rate of sunlight. (3) It can utilize the synergistic effect of the dual active sites in the alloy to regulate the progress of the reaction path and effectively improve the yield and selectivity of photocatalytic reduction of carbon dioxide to produce products with higher added value.

[0042] By introducing oxygen vacancies and AuCu alloy nanoparticles into the titanium dioxide semiconductor system, it is possible to effectively improve the generation efficiency of photo-generated electrons under visible light irradiation, achieve the directional transfer of photo-generated electrons to the AuCu alloy, and then regulate the reaction steps of photocatalytic reduction of carbon dioxide to synthesize acetic acid at the active sites of the AuCu alloy with strong carbon dioxide adsorption and reduction ability, realizing higher catalytic activity and selectivity.

[0043] According to the preparation method of the present invention, in step (a), the crystal form of the oxygen-deficient titanium dioxide is one or more of anatase, rutile, and brookite.

[0044] According to the preparation method of the present invention, in step (a), the mass concentration of the titanium dioxide powder in the suspension is 5-30 g / L, preferably 10-15 g / L; the mass concentration of polyvinylpyrrolidone in the suspension is 50-200 g / L, preferably 50-100 g / L; the mass concentration of ascorbic acid in the suspension is 10-50 g / L, preferably 10-20 g / L; the mass concentration of potassium bromide in the suspension is 20-50 g / L, preferably 35-40 g / L.

[0045] If the mass concentration of polyvinylpyrrolidone in the suspension is lower than 50 g / L, the AuCu alloy particles in the catalyst are likely to aggregate, resulting in uneven dispersion. If the mass concentration of ascorbic acid in the suspension is lower than 10 g / L and the mass concentration of potassium bromide in the suspension is lower than 20 g / L, the Au and Cu ions are difficult to be reduced to the form of AuCu alloy particles.

[0046] According to the preparation method of the present invention, in step (a), the heating is water bath heating, the temperature of the water bath heating is 20-90°C, preferably 70-90°C, and the stirring time under the heating condition is 5-20 min, preferably 5-10 min.

[0047] According to the preparation method of the present invention, in step (a), the total molar concentration of copper and gold chlorides in the suspension is 0.01-1 mol / L, preferably 0.02-0.1 mol / L; the molar ratio of copper chloride to gold chloride can be 0:1-1:0, preferably 5:1-1:5, and the holding stirring time is 2-5 h, preferably 3-4 h.

[0048] If the total molar concentration of copper and gold chlorides in the suspension is lower than 0.01 mol / L, it is difficult to form AuCu alloy particles and easy to form clusters.

[0049] According to the preparation method of the present invention, in step (b), the way to clean the precursor material is one or more of centrifugation, alcohol washing, water washing and ultrasonic cleaning, and it is cleaned 3-5 times; the drying temperature of the precursor material is 70-100°C, the vacuum degree <5 Pa, and the drying time is 1-30 h.

[0050] Among them, the preferred way to clean the precursor material is to use centrifugation and alcohol washing together. In the centrifugation, the rotation speed of the centrifuge is preferably 5000-50000 r / min, and the centrifugation time is preferably 1-10 min. In the alcohol washing, the alcohol used is preferably an alcohol with C1-C5. The way of using centrifugation and alcohol washing together can include performing multiple centrifugations and multiple alcohol washing methods. For example, centrifugation and alcohol washing can be carried out once, twice, three times, four times or five times or more respectively.

[0051] According to the preparation method of the present invention, in step (b), the drying temperature of the precursor material can be 50-120°C, preferably 70-100°C, and the drying time of the precursor material can be 1-30 h, preferably 5-20 h. Further, preferably, the precursor material is vacuum dried, and the vacuum degree of the vacuum drying is preferably less than 5 Pa.

[0052] According to the preparation method of the present invention, in step (b), the hydrogen concentration used for high-temperature calcination of the precursor material is 5-100%, preferably 5-10%, the carrier gas is one or more of argon, helium and nitrogen, preferably argon; the high-temperature calcination temperature is 300-600°C, preferably 300-400°C, and the calcination time is 2-4 h, preferably 2-3 h.

[0053] If the hydrogen concentration in the hydrogen atmosphere is less than 5%, the high-temperature calcination temperature is less than 300 °C, and the calcination time is less than 2 h, it is difficult for AuCu in the alloy to be reduced to the alloy and remains in the oxide form.

[0054] Second Aspect

[0055] The present invention also provides an oxygen-deficient titanium dioxide-supported AuCu alloy photocatalyst prepared by the preparation method according to the present invention.

[0056] Third Aspect

[0057] The present invention also provides a use of the oxygen-deficient titanium dioxide-supported AuCu alloy photocatalyst according to the present invention in the photocatalytic reduction of carbon dioxide to synthesize acetic acid. Among them, an aqueous solution of the photocatalyst with a concentration of 0.1 - 5 g / L is placed in a container filled with carbon dioxide and reacted under the full spectrum for 1 - 4 h.

[0058] Preferably, the use of the oxygen-deficient titanium dioxide-supported AuCu alloy photocatalyst according to the present invention in the photocatalytic reduction of carbon dioxide to synthesize acetic acid includes the following steps:

[0059] (a) Add the powder of the oxygen-deficient titanium dioxide-supported AuCu alloy photocatalyst to a container filled with water and uniformly disperse it by ultrasonic waves to obtain a suspension.

[0060] (b) Place the container containing the suspension into a light-transmitting sealed container, introduce carbon dioxide gas at a certain pressure, and react under the full spectrum.

[0061] Preferably, in the above step (a), the mass concentration of the photocatalyst in water can be 0.5 - 2 g / L, preferably 0.9 - 1 g / L; the volume of the suspension can be 1:10 - 1:2 of the volume of the container, preferably 3:10 - 5:10; the ultrasonic time can be 10 - 20 min, preferably 10 - 15 min.

[0062] Preferably, in step (b), the purity of the carbon dioxide gas can be 50% - 100%, preferably 90% - 100%; the gas pressure in the sealed container can be 0.1 MPa - 1 MPa, preferably 0.3 MPa - 0.5 MPa; the reaction time can be 1 - 10 h, preferably 3 - 4 h.

[0063] The dual active sites of the gold-copper alloy can effectively adsorb and activate carbon dioxide molecules, regulate the progress of the photocatalytic carbon dioxide reduction reaction to produce acetic acid, and improve the selectivity and yield of acetic acid product formation. The present invention utilizes the unique electronic structure and synergistic effect of the gold-copper alloy to regulate the energy band structure of the photocatalyst, significantly improving the absorption capacity and utilization efficiency of visible light.

[0064] Examples

[0065] The embodiments of the present invention will be described in detail below in conjunction with examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. For those not specified in the examples, they are carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0066] The main raw materials used in the examples are as follows: nano-titanium dioxide (P25, average particle size 20 nm); polyvinylpyrrolidone (K30); potassium bromide (purity 99.9%); L-ascorbic acid (purity 99.99%); chloroauric acid trihydrate (purity 99%); copper dichloride dihydrate (purity 99.99%); ethanol (purity 99.7%). All of the above reagents were purchased from Shanghai Macklin Biochemical Technology Co., Ltd.

[0067] Example 1

[0068] (a) Add 210 mg of polyvinylpyrrolidone, 240 mg of ascorbic acid, 600 mg of potassium bromide, etc. to 16 mL of an aqueous solution containing 200 mg of titanium dioxide, and stir at a speed of 500 revolutions per minute in a water bath at 80 °C for 5 min to make it uniformly dispersed. After adding 131.15 mg of chloroauric acid trihydrate and 11.42 mg of copper dichloride dihydrate and maintaining stirring for 3 h, the precipitate obtained by centrifugation at 10,000 r / min for 4 min is the precursor material;

[0069] (b) Centrifuge and wash the precursor material described in step (a) with ethanol at a speed of 10,000 revolutions per minute, with a centrifugation time of 4 min each time, repeat 3 times, then place it in a vacuum oven at 60 °C (vacuum degree <5 Pa) for overnight drying for 12 h, and then place it in a tubular furnace and calcine at 350 °C in a hydrogen atmosphere for 3 h to obtain the photocatalyst, denoted as AuCu / TiO 2-x photocatalyst.

[0070] Comparative Example 1

[0071] In step (a), 157.53 mg of chloroauric acid trihydrate and 0 mg of copper dichloride dihydrate were weighed, and the remaining steps were the same as those in Example 1, to obtain a photocatalyst of oxygen-deficient titanium dioxide supported with gold particles, denoted as Au / TiO 2-x .

[0072] Comparative Example 2

[0073] In step (a), 0 mg of chloroauric acid trihydrate and 68.18 mg of copper dichloride dihydrate were weighed, and the remaining steps were the same as those in Example 1, to obtain a photocatalyst of oxygen-deficient titanium dioxide supported with copper particles, denoted as Cu / TiO 2-x .

[0074] Comparative Example 3

[0075] In step (a), no metal chloride was added, and the remaining steps were the same as those in Example 1, to obtain an oxygen-deficient titanium dioxide photocatalyst, denoted as TiO 2-x .

[0076] Comparative Example 4

[0077] In step (a), no metal chloride was added, and calcination in a hydrogen atmosphere in a tubular furnace was not performed. The remaining steps were the same as those in Example 1, to obtain the described titanium dioxide (TiO 2 ) photocatalyst.

[0078] Transmission Electron Microscopy Test

[0079] Transmission electron microscope images were collected in transmission mode with an instrument acceleration voltage of 200 kV. An energy-dispersive spectrometer was used to analyze the elemental content and distribution of the selected area.

[0080] Figure 1 is the high-angle annular dark-field image of the transmission electron microscope of the AuCu / TiO 2-x photocatalyst prepared in Example 1, as shown in Figure 1 . In the AuCu / TiO 2-x photocatalyst, metals are uniformly dispersed in the form of nanoparticles on the surface of the TiO 2-x crystal.

[0081] Transmission Electron Microscopy and Energy Dispersive Spectroscopy Tests

[0082] Transmission electron microscope images were collected in transmission mode with an instrument acceleration voltage of 200 kV. An energy-dispersive spectrometer was used to analyze the elemental content and distribution of the selected area.

[0083] Sample preparation: Place a small amount of the sample in a 1.5 mL sample vial, add ethanol (with a purity of 99.9%) with a volume of 2 / 3 - 3 / 4, and ultrasonicate at room temperature for 20 min. Take 2 - 3 drops of the supernatant and place them on a microgrid. After air drying, perform the test.

[0084] Figure 2 (a) of which is the bright-field image of the AuCu / TiO 2-x photocatalyst prepared in Example 1; Figure 2 (b) of which is Figure 2 the line scan image of the energy spectrometer of the nanoparticles in (a) of which, as Figure 2 shown in (b) of which, the Au and Cu elements are evenly distributed in the metal particles, and it is an AuCu alloy.

[0085] Raman Spectroscopy Test

[0086] For Raman spectroscopy, the laser wavelength is selected as 532 nm at room temperature, and the test range is 100 - 1600 cm -1 , and the resolution is 2 cm -1 under the condition of testing.

[0087] Perform Raman spectroscopy tests on the photocatalysts obtained in Example 1 and Comparative Examples 1 - 4, and the results are as Figure 3 shown.

[0088] X-ray Diffraction (XRD) Test

[0089] First, place an appropriate amount of catalyst powder evenly in the groove of the sample stage of the X-ray diffractometer, and then level the surface and fix it on the diffractometer sample holder. The X-ray is excited by a Cu target, and λ is The scanning rate is 1 - 5° min -1 , and the scanning range (2θ) is 5 - 90°.

[0090] Perform X-ray diffraction (XRD) tests on the photocatalysts obtained in Example 1 and Comparative Examples 1 - 4, and the results are as Figure 4 shown.

[0091] As Figure 3 and Figure 4 shown, the crystal phase of the photocatalysts obtained in Example 1 and Comparative Examples 1 - 4 is the titanium dioxide crystal phase. As Figure 4 shown, the crystal form of titanium dioxide is the coexistence of anatase and rutile crystal phases; AuCu / TiO 2-x there is an AuCu alloy in the photocatalyst.

[0092] Electron Paramagnetic Resonance Spectroscopy Test

[0093] For electron paramagnetic resonance spectroscopy tests, the test temperature is selected as room temperature, the modulation frequency is selected as 100 kHz, and the modulation amplitude is selected as 10 G.

[0094] The photocatalysts obtained in Example 1 and Comparative Examples 1-4 were tested by electron paramagnetic resonance spectroscopy (ESR), and the results are as Figure 5 shown. Analyzing the concentration of oxygen vacancies in the AuCu / TiO 2-x photocatalyst, it can be seen from Figure 5 that an obvious signal peak appears at g = 2.003, indicating that there are abundant oxygen vacancies in the AuCu / TiO 2-x photocatalyst.

[0095] Ultraviolet-Visible Absorption Spectroscopy Test

[0096] The ultraviolet-visible absorption spectrum of the photocatalyst was tested using a solid ultraviolet-visible diffuse reflectance spectrometer. BaSO 4 powder was selected as the reference sample during the test, and the scanning range was 200 - 800 nm.

[0097] The ultraviolet-visible absorption spectrum (UV-Vis) of the photocatalysts obtained in Example 1 and Comparative Examples 1-4 was tested, and the results are as Figure 6 shown. Through the analysis of the ultraviolet-visible absorption spectrum in Figure 6 , it can be known that after constructing the oxygen vacancy engineering, the absorption ability of the photocatalyst for visible light is enhanced; after introducing the AuCu alloy, due to the local surface plasmon resonance effect, an obvious local surface plasmon resonance peak appears, further enhancing the absorption ability of the photocatalyst for visible light, which is beneficial to improving the photocatalytic activity.

[0098] Application Example 1

[0099] The photocatalysts obtained in Example 1 and Comparative Examples 1-4 were used for the experiment of photocatalytic reduction of carbon dioxide to synthesize acetic acid, including the following steps: at room temperature, 30 mL of a suspension with a photocatalyst concentration of 1 g / L was placed in a container filled with high-purity carbon dioxide (0.4 MPa), and the reaction was carried out under the full spectrum of a 300 W xenon lamp for 3 h. The specific results are as Figure 7 shown.

[0100] As shown by Figure 7 , the AuCu / TiO 2-x photocatalyst enhances the adsorption and activation of carbon dioxide through the alloy effect, and has the highest acetic acid synthesis efficiency of 56 μmol g -1 h -1 .

[0101] Acetic Acid Production Rate Cycling Test

[0102] Based on the method of Application Example 1, it was repeated five times for the AuCu / TiO 2-xThe photocatalyst was subjected to a cyclic stability test, and the results are as Figure 8 shown. It was found that after five photocatalytic carbon dioxide reduction tests, the acetic acid production rate of the photocatalyst did not decrease significantly, indicating that the photocatalyst has good stability.

[0103] It should be noted that although the technical solutions of the present invention are introduced by specific examples, those skilled in the art can understand that the present invention should not be limited thereto.

[0104] The embodiments of the present invention have been described above. The above description is exemplary and not exhaustive, and is also not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to technologies in the market, or to enable other ordinary skill in the art in the technical field to understand the embodiments disclosed herein.

Claims

1. A method for preparing an oxygen-deficient titanium dioxide-supported gold-copper alloy photocatalyst, characterized in that: The following steps are involved: (a) dispersing polyvinyl pyrrolidone, ascorbic acid, potassium bromide and titanium dioxide powder in water, stirring under heating conditions to obtain a suspension, adding copper and gold chlorides while stirring to obtain a precursor suspension; (b) subjecting the precursor suspension obtained in step (a) to solid-liquid separation to obtain a precursor material, washing and drying the precursor material, and calcining it at high temperature in a hydrogen atmosphere to obtain the oxygen-deficient titanium dioxide-loaded gold-copper alloy photocatalyst.

2. The preparation method according to claim 1, characterized in that: In step (a), the crystal form of the oxygen-deficient titanium dioxide is one or more of anatase, rutile and brookite.

3. The preparation method according to claim 1 or 2, characterized in that: In step (a), the mass concentration of the titanium dioxide powder in the suspension is 5 to 30 g / L; the mass concentration of the polyvinyl pyrrolidone in the suspension is 50 to 200 g / L; the mass concentration of the ascorbic acid in the suspension is 10 to 50 g / L; and the mass concentration of the potassium bromide in the suspension is 20 to 50 g / L.

4. The preparation method according to claim 1 or 2, characterized in that: In step (a), the heating is water bath heating, the water bath heating temperature is 20 to 90° C., and the stirring time under the heating conditions is 5 to 20 minutes.

5. The preparation method according to claim 1 or 2, characterized in that: In step (a), the total molar concentration of the copper and gold chlorides in the suspension is 0.01 to 1 mol / L, and the stirring time is 2 to 5 hours.

6. The preparation method according to claim 1 or 2, characterized in that: In step (b), the precursor material is cleaned by one or more of centrifugation, alcohol washing, water washing and ultrasonic cleaning for 3 to 5 times; the precursor material is dried at a temperature of 70 to 100° C., a vacuum degree of <5 Pa, and a drying time of 1 to 30 hours.

7. The preparation method according to claim 1 or 2, characterized in that: In step (b), the hydrogen concentration of the hydrogen atmosphere used when the precursor material is subjected to high-temperature calcination is 5-100%, and the carrier gas is one or more of argon, helium and nitrogen; the high-temperature calcination temperature is 300-600°C, and the calcination time is 2-4h.

8. An oxygen-deficient titanium dioxide-supported gold-copper alloy photocatalyst prepared according to the preparation method according to any one of claims 1 to 7.

9. Use of the oxygen-deficient titanium dioxide-supported gold-copper alloy photocatalyst according to claim 8 for photocatalytic reduction of carbon dioxide to synthesize acetic acid, characterized in that: A 0.1-5 g / L photocatalyst aqueous solution is placed in a container filled with high-purity carbon dioxide and reacted under the full spectrum for 1-4 hours.

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