A Cu single-atom intercalated hexagonal WO3 catalyst and its preparation method

Abstract

The present invention discloses a Cu single-atom intercalated hexagonal WO3 catalyst and a preparation method thereof. The hexagonal WO3 is dispersed in an alcohol solution, metal ions are added to obtain a mixed solution, the mixed solution is irradiated, after the irradiation is completed, the hexagonal WO3 is separated, washed, dried, and then calcined; the calcined hexagonal WO3 is dispersed in water, a copper source is added and ion exchange is carried out, and a Cu single-atom intercalated hexagonal WO3 catalyst is obtained after the ion exchange is completed. In the Cu single-atom intercalated hexagonal WO3 of the present invention, due to the strong interaction between the Cu single atoms in the pore structure and the hexagonal WO3, a surface plasmon resonance effect will be caused, thereby realizing the absorption of visible light and infrared light, greatly improving the utilization rate of visible light and infrared light by the hexagonal WO3, and this catalyst has broad application prospects in the fields of water treatment, air purification, energy conversion, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material preparation, and particularly relates to a Cu single-atom intercalated hexagonal WO3 catalyst and a preparation method thereof. Background Art

[0002] As an environmentally friendly catalyst, hexagonal WO3 is widely used in fields such as water treatment and air purification. Due to the relatively wide bandgap (2.7 - 2.8 eV) of hexagonal WO3, its visible light absorption ability is limited. And the solar spectrum mainly consists of visible light and infrared light, which greatly limits the application of hexagonal WO3 in the natural environment.

[0003] Regarding the problem of insufficient light absorption of the above-mentioned hexagonal WO3, the current main improvement methods mainly include constructing composite structures, introducing heteroatoms, surface modification of catalysts, etc. Composite hexagonal WO3 with other materials, such as carbon-nitrogen composite, titanium dioxide composite, graphene composite, etc. This method can increase the adsorption performance and optical response ability of the catalyst, but it will also increase the preparation cost and difficulty. Introduce appropriate heteroatoms into the crystal structure of hexagonal WO3, such as carbon, nitrogen, iron, etc. This method can enhance the light absorption ability and photocatalytic activity, but it may also introduce new problems, such as chemical instability and toxicity, etc. Modify the light absorption performance of hexagonal WO3 by changing its surface structure and chemical properties, such as introducing loaders, surface modifiers, etc. This method may lead to a decrease in catalytic activity or an increase in the selectivity of side reactions due to the change of active sites. The current improvement methods still have certain limitations in improving the photocatalytic efficiency and environmental adaptability of hexagonal WO3, and more in-depth research and exploration are needed. Summary of the Invention

[0004] In view of the above problems, the object of the present invention is to provide a Cu single-atom intercalated hexagonal WO3 catalyst and a preparation method thereof. This method can improve the visible light absorption by precisely loading Cu single atoms into the pore structure of hexagonal WO3. The preparation method is simple to operate and can be mass-produced. Most importantly, Cu can be precisely inserted into the pore structure without changing the active sites of the catalyst, and the obtained catalyst has the advantages of high efficiency, stability, corrosion resistance, and low cost.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A preparation method of a Cu single-atom intercalated hexagonal WO3 catalyst, comprising the following steps:

[0007] Disperse hexagonal WO3 in an alcohol solution, add metal ions to obtain a mixed solution, irradiate the mixed solution, separate hexagonal WO3 after the irradiation is completed, wash, dry, and then calcine.

[0008] Disperse the calcined hexagonal WO3 in water, add a copper source and perform ion exchange. After the ion exchange is completed, a Cu single-atom intercalated hexagonal WO3 catalyst is obtained.

[0009] Furthermore, the alcohol solution is an aqueous ethanol solution with a volume concentration of 1% - 10%, and the dosage ratio of hexagonal WO3 to the alcohol solution is 0.1 g : 50 mL.

[0010] Furthermore, the metal ion is Li + , Na + and K + or one or more of them.

[0011] Furthermore, the total concentration of metal ions in the mixed solution is 0.08 - 1 mol / L.

[0012] Furthermore, the light irradiation is carried out under a xenon lamp for 1 - 3 hours.

[0013] Furthermore, the calcination temperature is 100 - 320 °C and the calcination time is 1 - 24 hours.

[0014] Furthermore, the calcination is carried out in an oxygen-containing atmosphere, and the volume content of oxygen in the oxygen-containing atmosphere is greater than 1%.

[0015] Furthermore, the ion exchange time is 1 - 24 hours, the ion exchange temperature is between 20 - 80 °C, and the ion exchange is carried out in the dark.

[0016] Furthermore, the copper source is copper nitrate or copper chloride, and the concentration of copper in the mixture after adding the copper source is between 0.8 - 100 mmol / L.

[0017] A Cu single-atom intercalated hexagonal WO3 catalyst prepared by the method as described above.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] In the present invention, Cu single atoms are first inserted into hexagonal WO3. Due to the strong interaction between the Cu single atoms in the pore structure and hexagonal WO3, it will cause the surface plasmon resonance effect, thereby realizing the absorption of visible light and infrared light, and greatly improving the utilization rate of hexagonal WO3 for visible light and infrared light. Secondly, Cu is loaded into the pore structure of hexagonal WO3 without changing the basic structure of the material, thus not introducing additional electron-hole recombination centers; and the Cu single atoms do not exist on the surface of the catalyst, so they will not cause changes in the surface active sites, and therefore will not lead to changes in the usage scenarios. The hexagonal WO3 with precisely fixed single atoms in the present invention can improve the absorption of hexagonal WO3 in the visible light range and infrared light range, and has broad application prospects in the fields of water treatment, air purification, energy conversion, etc., and can play an important role in the fields of environmental protection and resource utilization.

[0020] Furthermore, ethanol is used as a hole sacrificial agent, which plays a key role in promoting metal ions to enter the pore structure of hexagonal WO3.

[0021] Furthermore, irradiate under a xenon lamp for 1 - 3 hours to enable metal ions to enter the pore structure of hexagonal WO3.

[0022] Furthermore, calcine at 100 - 320 °C. The purpose is to make the hydrogen on the surface of hexagonal WO3 react with oxygen to remove the surface hydrogen and change the surface properties.

[0023] Furthermore, in the present invention, Li + , Na + and K + are first introduced into the pore structure of hexagonal WO3, and then Cu is introduced into the pore structure of hexagonal WO3 by an exchange method. Description of the Drawings

[0024] Figure 1 It is the absorption spectrum diagram of hexagonal WO3 and hexagonal WO3 after loading Cu.

[0025] Figure 2 It is the N2 adsorption-desorption curve of hexagonal WO3 and hexagonal WO3 after loading Cu.

[0026] Figure 3 It is the scanning electron microscope diagram of hexagonal WO3 and hexagonal WO3 after loading Cu; among them, (a) is hexagonal WO3, and (b) is hexagonal WO3 after loading Cu. Detailed Embodiments

[0027] The technical solutions, objectives and advantages of the invention will be further described in detail below in combination with specific embodiments.

[0028] A preparation method of a Cu single-atom intercalated hexagonal WO3 catalyst of the present invention includes the following steps:

[0029] Disperse hexagonal WO3 in a solution, add metal ions and irradiate with light for 1 - 3 hours under a xenon lamp, so that the metal ions enter the pore structure of hexagonal WO3. After the light irradiation is completed, separate the hexagonal WO3 and wash it thoroughly. The washing is carried out with water or ethanol, and the number of washing times is not less than 10 times, and then dry it. Calcinate the dried hexagonal WO3 at a high temperature in an oxygen-containing atmosphere. The calcination temperature is 100 - 320 °C, the oxygen content (volume content) of the oxygen-containing atmosphere is greater than 1%, and the calcination time is 1 - 24 hours. The purpose of calcination is to make the hydrogen on the surface of hexagonal WO3 react with oxygen to remove the surface hydrogen and change the surface properties.

[0030] Among them, the solution is an aqueous ethanol solution with a volume concentration of 1% - 10%.

[0031] The metal ions are Li + , Na + and K + in any ratio of one or more of them mixed.

[0032] The total concentration of the metal ions is 0.08 - 1 mol / L.

[0033] Disperse the calcined hexagonal WO3 in water, add a copper source for ion exchange. The ion exchange time is 1 - 24 hours, the ion exchange temperature is between 20 - 80 °C, and the ion exchange process needs to be carried out in the dark. After the ion exchange is completed, the Cu single-atom intercalated hexagonal WO3 catalyst can be obtained. Among them, the copper source is one of copper nitrate or copper chloride, and the copper ion concentration is between 0.8 - 100 mmol / L.

[0034] A Cu single-atom intercalated hexagonal WO3 catalyst prepared according to the above method.

[0035] The present invention realizes improving the visible light absorption performance of hexagonal WO3 without changing the surface active sites and without causing changes in product selectivity through a simple and efficient modification method.

[0036] The process of photocatalytic CO2 reduction test in the present invention is as follows:

[0037] The performance evaluation of the prepared photocatalyst for CO2 photoreduction was carried out in a stainless-steel reactor with a volume of 200 mL. The bottom and the surrounding sides of the reactor were made of stainless steel, and the upper surface was a quartz window (with a diameter of 50 mm). The photocatalyst (0.03 g) was evenly dispersed in 3 mL of deionized water, and then transferred to a petri dish with a diameter of 50 mm. It was vacuum dried at 60 °C for 24 hours to evenly cover the sample in the petri dish. Then, the petri dish containing the sample was placed into the reactor, and at the same time, 100 μL of deionized water was dropped into the reactor. The reactor was rinsed 10 times with high-purity carbon dioxide (99.999%). Subsequently, a certain amount of high-purity carbon dioxide was injected into the reactor to keep the pressure at 0.1 Mpa. The CEL-HXF300-T3300 xenon lamp light source system of Beijing Zhongjiao Jinyuan Technology Co., Ltd. was used to simulate sunlight to irradiate the surface of the sample through the quartz window for the photocatalytic reaction. The products were detected by a gas chromatograph (7890B, Agilent, USA). The flame ionization detector (FID) was used to detect the yields of CH4 and CO, and the thermal conductivity detector (TCD) was used to detect O2. The production rate of CO2 reduction products was expressed in μmol g -1 h -1 That is, it was converted to the amount of products catalytically generated per gram of catalyst per hour (μmol).

[0038] Example 1

[0039] 1) Take 0.1 g of hexagonal WO3 and disperse it in a mixed solution of 50 mL of ethanol and water, where the volume concentration of ethanol is 5%.

[0040] 2) Add 1 mL of LiCl (5 mol / L) solution to the above solution.

[0041] 3) Irradiate the solution obtained in the above step under a xenon lamp for 1 hour.

[0042] 4) Centrifuge and separate the irradiated hexagonal WO3, and wash it alternately with ethanol and water 10 times, and then dry it at 70 °C for 12 hours.

[0043] 5) Transfer the above dried catalyst into a magnetic boat and calcine it at 300 °C for 12 hours in an air atmosphere.

[0044] 6) Disperse the calcined catalyst in 50 mL of water, add 10 mL of copper nitrate (50 mmol / L) to it, and stir it at 80 °C for 24 hours for ion exchange under dark conditions. After the ion exchange is completed, centrifuge and separate the precipitate, wash it alternately with water and ethanol 10 times, and dry it at 70 °C for 12 hours to obtain the Cu single-atom intercalated hexagonal WO3 catalyst, denoted as WO3-Li-Cu.

[0045] The absorption spectrum of the obtained WO3-Li-Cu was tested, and the results are as Figure 1 shown. After introducing Cu single atoms, the absorbability of the sample for visible light and infrared light was significantly enhanced. The color of unmodified hexagonal WO3 is white, and the color of the sample with Cu single atoms inserted is black, which also proves that the introduction of Cu single atoms enhances the light absorption performance of hexagonal WO3. In addition, the N2 adsorption-desorption isotherm tests were carried out on the original WO3 and WO3-Li-Cu samples, and the results are as Figure 2 shown. After introducing Cu single atoms, the adsorption curve of the sample does not show a sudden change in the low-pressure range, which proves that Cu has entered the pore structure of hexagonal WO3. The photocatalytic CO2 reduction test was carried out on the synthesized samples, and it was found that the CO production rate of WO3-Li-Cu was 30 μmol g -1 h -1 , which is 10 times that of unmodified hexagonal WO3 (2.9 μmol g -1 h -1 ), proving that the catalytic performance is significantly improved after the introduction of Cu. As Figure 3 shown in (a) and (b) therein, the morphology of WO3 before and after the introduction of Cu did not change significantly, and both were nanorod-like structures.

[0046] Example 2

[0047] 1) Take 0.1 g of hexagonal WO3 and disperse it in a mixed solution of 50 mL of ethanol and water, where the volume concentration of ethanol is 5%.

[0048] 2) Add 1 mL of KCl (5 mol / L) solution to the above solution.

[0049] 3) Irradiate the solution obtained in the above step under a xenon lamp for 1 hour.

[0050] 4) Centrifuge and separate the irradiated hexagonal WO3, wash it alternately with ethanol and water 10 times, and then dry it at 70 °C for 12 hours.

[0051] 5) Transfer the dried catalyst into a magnetic boat and calcine it at 300 °C for 12 hours in an air atmosphere.

[0052] 6) Disperse the calcined catalyst in 50 mL of water, add 10 mL of copper nitrate (50 mmol / L) to it, and stir it at 80 °C for 24 hours for ion exchange under dark conditions. After the ion exchange is completed, centrifuge and separate the precipitate, wash it alternately with water and ethanol 10 times, and dry it at 70 °C for 12 hours to obtain a Cu single atom-inserted hexagonal WO3 catalyst, denoted as WO3-K-Cu.

[0053] The synthesized samples were tested for photocatalytic CO2 reduction, and it was found that the CO production rate of WO3-K-Cu was 25 μmol g -1 h -1 , which was 8 times that of the unmodified hexagonal WO3 (2.9 μmol g -1 h -1 ), demonstrating a significant improvement in catalytic performance after the introduction of Cu.

[0054] Example 3

[0055] 1) Take 0.1 g of hexagonal WO3 and disperse it in a mixed solution of 50 mL of ethanol and water, where the volume concentration of ethanol is 5%.

[0056] 2) Add 1 mL of NaCl (5 mol / L) solution to the above solution.

[0057] 3) Irradiate the solution obtained in the above step under a xenon lamp for 1 hour.

[0058] 4) Centrifuge and separate the irradiated hexagonal WO3, wash it alternately with ethanol and water 10 times, and then dry it at 70 °C for 12 hours.

[0059] 5) Transfer the dried catalyst into a magnetic boat and calcine it at 300 °C for 12 hours in an air atmosphere.

[0060] 6) Disperse the calcined catalyst in 50 mL of water, add 10 mL of copper nitrate (50 mmol / L) to it, and stir it at 80 °C for 24 hours for ion exchange under dark conditions. After the ion exchange is completed, centrifuge and separate the precipitate, wash it alternately with water and ethanol 10 times, and dry it at 70 °C for 12 hours to obtain a Cu single-atom intercalated hexagonal WO3 catalyst, denoted as WO3-K-Cu.

[0061] The synthesized samples were tested for photocatalytic CO2 reduction, and it was found that the CO production rate of WO3-K-Cu was 27 μmol g -1 h -1 , which was 9 times that of the unmodified hexagonal WO3 (2.9 μmol g -1 h -1 ), demonstrating a significant improvement in catalytic performance after the introduction of Cu.

[0062] Example 4

[0063] 1) Take 0.1 g of hexagonal WO3 and disperse it in a mixed solution of 50 mL of ethanol and water, where the volume concentration of ethanol is 1%.

[0064] 2) Add LiCl solution (5 mol / L) and KCl solution (5 mol / L) to the above solution to obtain a mixed solution, and the Li+ and K + The total concentration is 0.08 mol / L, and the molar ratio of Li + and K + is 1:1;

[0065] 3) Irradiate the mixed solution obtained in the above step under a xenon lamp for 3 hours.

[0066] 4) Centrifuge and separate the hexagonal WO3 after irradiation, and alternately wash it 10 times with ethanol and water, and then dry it at 70 °C for 12 hours.

[0067] 5) Transfer the dried catalyst above into a magnetic boat, and calcine it at 100 °C for 24 hours in an oxygen-containing atmosphere with an oxygen volume content of 2%.

[0068] 6) Disperse the calcined catalyst in 50 mL of water, add copper nitrate (50 mmol / L) to it to obtain a mixed solution. The concentration of copper ions in the mixed solution is 50 mmol / L. Stir the mixed solution at 80 °C for 1 hour under light-shielded conditions for ion exchange. After the ion exchange is completed, centrifuge and separate the precipitate, alternately wash it 10 times with water and ethanol, and dry it at 70 °C for 12 hours to obtain the Cu single-atom intercalated hexagonal WO3 catalyst.

[0069] Example 5

[0070] 1) Take 0.1 g of hexagonal WO3 and disperse it in a mixed solution of 50 mL of ethanol and water, where the volume concentration of ethanol is 10%.

[0071] 2) Add an NaCl (5 mol / L) solution to the above solution to obtain a mixed solution, and the concentration of Na + in the mixed solution is 0.5 mol / L;

[0072] 3) Irradiate the mixed solution obtained in the above step under a xenon lamp for 2.5 hours.

[0073] 4) Centrifuge and separate the hexagonal WO3 after irradiation, and alternately wash it 10 times with ethanol and water, and then dry it at 70 °C for 12 hours.

[0074] 5) Transfer the dried catalyst above into a magnetic boat, and calcine it at 320 °C for 1 hour in an oxygen-containing atmosphere with an oxygen volume content of 10%.

[0075] 6) Disperse the calcined catalyst in 50 mL of water, add copper chloride (50 mmol / L) thereto to obtain a mixed solution with a copper ion concentration of 100 mmol / L in the mixed solution. Stir the mixed solution for 24 hours at 20 °C under light-shielded conditions for ion exchange. After the ion exchange is completed, centrifuge to separate the precipitate, wash it 10 times alternately with water and ethanol, and dry it at 70 °C for 12 hours to obtain a Cu single-atom intercalated hexagonal WO3 catalyst.

[0076] Example 6

[0077] 1) Take 0.1 g of hexagonal WO3 and disperse it in a mixed solution of 50 mL of ethanol and water, where the volume concentration of ethanol is 7%.

[0078] 2) Add a LiCl (5 mol / L) solution to the above solution to obtain a mixed solution with a Li + concentration of 1 mol / L;

[0079] 3) Irradiate the mixed solution obtained in the above step with a xenon lamp for 2 hours.

[0080] 4) Centrifuge the light-irradiated hexagonal WO3 and wash it 10 times alternately with ethanol and water, and then dry it at 70 °C for 12 hours.

[0081] 5) Transfer the above-dried catalyst into a magnetic boat and calcine it at 200 °C for 15 hours in an oxygen-containing atmosphere with an oxygen volume content of 20%.

[0082] 6) Disperse the calcined catalyst in 50 mL of water, add copper nitrate (50 mmol / L) thereto to obtain a mixed solution with a copper ion concentration of 0.8 mmol / L in the mixed solution. Stir the mixed solution for 10 hours at 50 °C under light-shielded conditions for ion exchange. After the ion exchange is completed, centrifuge to separate the precipitate, wash it 10 times alternately with water and ethanol, and dry it at 70 °C for 12 hours to obtain a Cu single-atom intercalated hexagonal WO3 catalyst.

[0083] Comparative Example 1

[0084] 1) Take 0.1 g of hexagonal WO3 and disperse it in a mixed solution of 50 mL of ethanol and water, where the volume concentration of ethanol is 5%.

[0085] 2) Irradiate the solution obtained in the above step with a xenon lamp for 1 hour.

[0086] 3) Centrifuge the light-irradiated hexagonal WO3 and wash it 10 times alternately with ethanol and water, and then dry it at 70 °C for 12 hours.

[0087] 4) Transfer the dried catalyst above into a magnetic boat and calcine it at 300 °C for 12 hours in an air atmosphere.

[0088] 5) Disperse the calcined catalyst in 50 mL of water, add 10 mL of copper nitrate (50 mmol / L) to it, and stir for 24 hours at 80 °C under light-shielded conditions for ion exchange. After the ion exchange is completed, centrifuge to separate the precipitate, wash it 10 times alternately with water and ethanol, and dry it at 70 °C for 12 hours to obtain the final catalyst, denoted as WO3-Cu.

[0089] For the synthesized samples, photocatalytic CO2 reduction tests were carried out, and it was found that the CO production rate of WO3-Cu was 3.1 μmol g -1 h -1 , and the catalytic performance of WO3 (2.9 μmol g -1 h -1 ) was not much different. The color of WO3-Cu was white, indicating that there was no change in the light absorption performance.

[0090] Comparative Example 2

[0091] 1) Take 0.1 g of hexagonal WO3 and disperse it in a mixed solution of 50 mL of ethanol and water, where the volume concentration of ethanol is 5%.

[0092] 2) Add 1 mL of LiCl (5 mol / L) solution to the above solution.

[0093] 3) Irradiate the solution obtained in the above step under a xenon lamp for 1 hour.

[0094] 4) Centrifuge and separate the irradiated hexagonal WO3, and wash it 10 times alternately with ethanol and water, and then dry it at 70 °C for 12 hours.

[0095] 5) Disperse the dried catalyst in 50 mL of water, add 10 mL of copper nitrate (50 mmol / L) to it, and stir for 24 hours at 80 °C under light-shielded conditions for ion exchange. After the ion exchange is completed, centrifuge to separate the precipitate, wash it 10 times alternately with water and ethanol, and dry it at 70 °C for 12 hours to obtain the final catalyst.

[0096] For the synthesized samples, photocatalytic CO2 reduction tests were carried out, and it was found that the CO production rate of the obtained catalyst was 2.4 μmol g -1 h -1 , and the catalytic performance was lower than that of WO3. Further tests found that a large amount of Cu was contained on the surface of the obtained catalyst, which was mainly due to the fact that H on the surface was not removed, so that Cu replaced H on the surface of the catalyst. A large number of Cu atoms accumulated on the surface of the catalyst, becoming the electron-hole recombination center and reducing the catalytic performance of the catalyst.

[0097] Comparative Example 3

[0098] 1) Take 0.1 g of hexagonal WO3 and disperse it in 50 mL of water.

[0099] 2) Add 1 mL of LiCl (5 mol / L) solution to the above solution.

[0100] 3) Irradiate the solution obtained in the above step with a xenon lamp for 1 hour.

[0101] 4) Centrifuge the irradiated hexagonal WO3 and wash it alternately with ethanol and water 10 times, and then dry it at 70 °C for 12 hours.

[0102] 5) Transfer the dried catalyst above into a magnetic boat and calcine it at 300 °C for 12 hours in an air atmosphere.

[0103] 6) Disperse the calcined catalyst in 50 mL of water, add 10 mL of copper nitrate (50 mmol / L) to it, and stir for 24 hours at 80 °C for ion exchange. After the ion exchange is completed, centrifuge to separate the precipitate, wash it alternately with water and ethanol 10 times, and dry it at 70 °C for 12 hours to obtain the final catalyst.

[0104] Perform photocatalytic CO2 reduction tests on the synthesized samples and find that there is little difference in the catalytic performance between the modified catalyst (3.1 μmol g -1 h -1 ) and the WO3 catalyst.

[0105] Comparative Example 4

[0106] 1) Take 0.1 g of hexagonal WO3 and disperse it in a mixed solution of 50 mL of ethanol and water, where the volume concentration of ethanol is 5%.

[0107] 2) Add 1 mL of LiCl (5 mol / L) solution to the above solution.

[0108] 3) Centrifuge the hexagonal WO3 and wash it alternately with ethanol and water 10 times, and then dry it at 70 °C for 12 hours.

[0109] 4) Transfer the dried catalyst above into a magnetic boat and calcine it at 300 °C for 12 hours in an air atmosphere.

[0110] 5) Disperse the calcined catalyst in 50 mL of water, add 10 mL of copper nitrate (50 mmol / L) to it, and stir for 24 hours in the dark at 80 °C for ion exchange. After the ion exchange is completed, centrifuge to separate the precipitate, wash it alternately with water and ethanol 10 times, and dry it at 70 °C for 12 hours to obtain the final catalyst.

[0111] The photocatalytic CO2 reduction test was carried out on the synthesized samples, and it was found that the performance of the modified catalyst (3.3 μmol g -1 h -1 ) decreased compared with that of WO3 catalyst.

[0112] Comparative Example 5

[0113] 1) Take 0.1 g of hexagonal WO3 and disperse it in a mixed solution of 50 mL of ethanol and water, where the volume concentration of ethanol is 5%.

[0114] 2) Add 1 mL of LiCl (5 mol / L) solution to the above solution.

[0115] 3) Irradiate the solution obtained in the above step with a xenon lamp for 1 hour.

[0116] 4) Centrifuge the irradiated hexagonal WO3 and wash it alternately with ethanol and water 10 times, and then dry it at 70 °C for 12 hours.

[0117] 5) Transfer the dried catalyst above into a magnetic boat and calcine it at 300 °C for 12 hours in an air atmosphere.

[0118] 6) Disperse the calcined catalyst in 50 mL of water and stir it in the dark at 80 °C for 24 hours. After stirring, centrifuge to separate the precipitate, wash it alternately with water and ethanol 10 times, and dry it at 70 °C for 12 hours to obtain the final catalyst.

[0119] The photocatalytic CO2 reduction test was carried out on the synthesized samples, and it was found that the performance of the modified catalyst (3.2 μmol g -1 h -1 ) was not much different from that of WO3 catalyst.

[0120] Comparative Example 6

[0121] 1) Take 0.1 g of hexagonal WO3 and disperse it in a mixed solution of 50 mL of ethanol and water, where the volume concentration of ethanol is 5%.

[0122] 2) Add 1 mL of LiCl (5 mol / L) solution to the above solution.

[0123] 3) Irradiate the solution obtained in the above step with a xenon lamp for 1 hour.

[0124] 4) Centrifuge the irradiated hexagonal WO3 and wash it alternately with ethanol and water 10 times, and then dry it at 70 °C for 12 hours.

[0125] 5) Transfer the dried catalyst above into a boat and calcine it at 300 °C in an air atmosphere for 12 hours.

[0126] 6) Disperse the calcined catalyst in 50 mL of water, add 10 mL of copper nitrate (50 mmol / L) thereto, and stir at 80 °C for 24 hours under light conditions for ion exchange. After the ion exchange is completed, centrifuge to separate the precipitate, wash it 10 times alternately with water and ethanol, and dry it at 70 °C for 12 hours to obtain the final catalyst.

[0127] Perform photocatalytic CO2 reduction tests on the synthesized samples and find that the modified catalyst (2.3 μmol g -1 h -1 ) has worse catalytic performance than the WO3 catalyst.

[0128] By comparing Comparative Example 1 with Example 1, it can be seen that without the introduction of metal ions, Cu cannot enter the pore structure of hexagonal WO3.

[0129] By comparing Comparative Example 2 with Examples 1-3, it can be seen that oxidizing the surface H atoms in an aerobic atmosphere is crucial for precisely controlling the loading position of Cu.

[0130] By comparing Comparative Example 3 with Examples 1-3, it can be seen that the presence of ethanol in the solution plays a key role in promoting the entry of ions into the pore structure of hexagonal WO3 as a hole sacrificial agent.

[0131] By comparing Comparative Example 4 with Examples 1-3, it can be seen that light is the driving force for metal ions to enter the pore structure of hexagonal WO3.

[0132] By comparing Comparative Example 5 with Examples 1-3, it can be seen that the introduction of Cu single atoms is the real reason for the improvement of the catalytic performance of the material catalyst.

[0133] By comparing Comparative Example 6 with Examples 1-3, it can be seen that the real reason for the improvement of the catalytic performance of the material catalyst with Cu single atoms entering the pore structure of hexagonal WO3, and controlling the non-deposition of Cu on the catalyst surface is also an important factor to ensure that the catalytic performance does not decrease.

[0134] In the present invention, the photo-generated electrons generated by hexagonal WO3 itself drive metal ions (Li + , Na + , K +) Enter its pore structure. By ion exchange, Cu is replaced into its pore structure, enhancing the light absorption performance of hexagonal WO3. The H atoms are removed by calcination, making the loading sites of Cu single and not triggering changes in catalytic sites. The preparation method of Cu single-atom loaded hexagonal WO3 in the present invention is simple, highly versatile, the loading position of single atoms is precisely controllable, the prepared catalyst has a high Cu single-atom loading amount, excellent photocatalytic performance, and strong stability.

[0135] In the aspect of water treatment, by using the catalyst of the present invention, harmful substances can be efficiently mineralized into harmless small molecules such as CO2 and H2O, thus realizing the purification and reuse of water.

[0136] The catalyst of the present invention can also simplify the research of chemical reaction systems, such as redox reactions of organic small molecules and organic synthesis reactions, etc. In the aspect of air purification, the catalyst of the present invention can convert harmful gases in the air, such as nitrogen dioxide, formaldehyde, etc., into harmless water and carbon dioxide, and has the characteristics of fast efficiency, good stability, etc.

[0137] Fixing the catalyst of the present invention to ventilation ducts or indoor decoration materials can achieve the effect of continuously purifying indoor air. Further, the catalyst of the present invention can also be used for photocatalytic water splitting to produce hydrogen, photocatalytic carbon dioxide reduction, etc.

Claims

1. A preparation method of a Cu single-atom inserted hexagonal WO3 catalyst, characterized in that, Comprising the following steps: Disperse hexagonal WO3 in an alcohol solution, add metal ions to obtain a mixed solution, irradiate the mixed solution with light, separate hexagonal WO3 after the irradiation is completed, wash and dry it, and then carry out calcination; Disperse the calcined hexagonal WO3 in water, add a copper source and carry out ion exchange, and obtain a Cu single-atom intercalated hexagonal WO3 catalyst after the ion exchange is completed; The metal ion is Li + , Na + , and K + or one or more of them; The irradiation with light is carried out under a xenon lamp for 1 - 3 hours; The calcination temperature is 100 - 320 °C, and the calcination time is 1 - 24 hours; The calcination is carried out in an oxygen-containing atmosphere, and the volume content of oxygen in the oxygen-containing atmosphere is greater than 1%; 2. The preparation method of a Cu single-atom intercalated hexagonal WO3 catalyst according to claim 1, characterized in that, The alcohol solution is an ethanol aqueous solution with a volume concentration of 1% - 10%, and the dosage ratio of hexagonal WO3 to the alcohol solution is 0.1 g:50 mL; 3. The preparation method of a Cu single-atom inserted hexagonal WO3 catalyst according to claim 1, wherein, The total concentration of metal ions in the mixed solution is 0.08 - 1 mol / L; 4. The preparation method of a Cu single-atom intercalated hexagonal WO3 catalyst according to claim 1, characterized in that, The ion exchange time is 1 - 24 hours, the ion exchange temperature is between 20 - 80 °C, and the ion exchange is carried out in the dark; 5. The preparation method of a Cu single-atom inserted hexagonal WO3 catalyst according to claim 1, characterized in that, The copper source is copper nitrate or copper chloride, and the concentration of copper in the mixture after adding the copper source is between 0.8 - 100 mmol / L; 6. A Cu single-atom intercalated hexagonal WO3 catalyst prepared by the method according to any one of claims 1 - 5.

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