A bifunctional membrane photocatalyst and a preparation method and application thereof

Abstract

The application discloses a kind of bifunctional membrane photocatalyst and its preparation method and application, the bifunctional membrane photocatalyst includes membrane, catalyst A is loaded in the aperture of the membrane, and the part of catalyst A loaded in aperture protrudes from the surface of membrane, noble metal is coated on the catalyst A protruding from the surface of membrane, catalyst B is coated on noble metal;Wherein, catalyst A is selected from at least one of cuprous oxide, copper phthalocyanine, cobalt phthalocyanine, nickel phthalocyanine and g-C3N4;Catalyst B is selected from at least one of titanium dioxide, bismuth vanadate, zinc oxide, bismuth tungstate and tungsten trioxide.The photocatalyst of the application has good stability and catalytic performance, and avoids the reaction between oxidation end and reduction end, prevents mutual interference and pollution of both.In addition, the photocatalyst has the advantages of flexible combination, simple preparation method, easy to control preparation conditions, no pollution, has certain research and application value.

Description

Technical Field

[0001] This invention belongs to the field of photocatalyst technology, specifically relating to a bifunctional film photocatalyst, its preparation method and application, and more specifically, to a bifunctional film photocatalyst, its preparation method and the application of the photocatalyst in photocatalytic carbon dioxide reduction and water oxidation. Background Technology

[0002] Photocatalysis utilizes electron-hole separation to simultaneously achieve oxidation and reduction reactions. To achieve highly efficient bifunctional photocatalysis, both reactions on both sides must be optimized simultaneously. An ideal bifunctional photocatalytic system should possess the following characteristics: 1) a matched catalyst combination, as single-component catalysts lack suitable band gaps and valence and conduction band positions; 2) a suitable reaction combination, as photocatalysis can simultaneously perform redox reactions, thus requiring the selection of matched redox half-reactions for the bifunctional photocatalytic system; 3) an optimal environment for simultaneously achieving both half-reactions; 4) ideal stability, adapting to strong light and the influence of oxidants and reductants; and 5) a simple synthesis method and relatively low cost, enabling practical applications.

[0003] Membrane photocatalytic systems possess advantages such as large specific surface area, abundant active sites, effective substance separation, and broad application prospects, and are currently being used in the field of photocatalytic degradation wastewater treatment. However, the application of membrane photocatalysts in photocatalytic carbon dioxide reduction remains limited. Meanwhile, photocatalytic water oxidation to produce hydrogen peroxide is an effective method for obtaining commonly used hydrogen peroxide because it avoids the difficulties of storing and transporting high-concentration hydrogen peroxide and the highly polluting preparation process, and allows for in-situ use, making it an effective method for future hydrogen peroxide production. However, a photocatalyst capable of achieving these two cost-effective bifunctional reactions has not yet been realized in current membrane photocatalysts. Furthermore, current membrane photocatalyst processes suffer from technical crudeness, simply loading the catalyst onto a membrane substrate, which reduces catalyst efficiency and wastes the membrane's separation performance. Summary of the Invention

[0004] To improve the above-mentioned technical problems, the present invention provides a bifunctional membrane photocatalyst, wherein the photocatalyst includes a membrane, catalyst A is loaded in the pores of the membrane, and the portion of catalyst A loaded in the pores protrudes from the surface of the membrane, a noble metal is coated on the catalyst A protruding from the surface of the membrane, and catalyst B is coated on the noble metal.

[0005] Wherein, catalyst A is selected from at least one of cuprous oxide, copper phthalocyanine, cobalt phthalocyanine, nickel phthalocyanine, and g-C3N4; preferably, catalyst A is cuprous oxide;

[0006] The catalyst B is selected from at least one of titanium dioxide, bismuth vanadate, zinc oxide, bismuth tungstate, and tungsten trioxide.

[0007] According to an embodiment of the present invention, a portion of the catalyst A is located in the pores of the membrane, and a portion protrudes from the surface of the membrane.

[0008] According to an embodiment of the present invention, the loading density of catalyst A is 0.05-10 g / m³. 2 Preferred concentration: 0.5-5 g / m 2 Preferably 0.8-3 g / m 2 More preferably, the loading density is 2 g / m³. 2 .

[0009] According to an embodiment of the present invention, the membrane is selected from at least one of polytetrafluoroethylene membrane, polyvinylidene fluoride membrane, cellulose acetate membrane, nylon filter membrane, and polyethersulfone membrane; preferably, the pore size of the membrane is 0.1-1 micrometer, more preferably, the pore size is 0.22 micrometers. Preferably, the membrane is a polytetrafluoroethylene membrane.

[0010] According to an embodiment of the present invention, the precious metal is selected from at least one of gold, silver, platinum and palladium; preferably silver.

[0011] According to an embodiment of the present invention, the thickness of the noble metal is 3-300 nm; preferably 10-50 nm, for example 30 nm.

[0012] According to an embodiment of the present invention, the thickness of catalyst B is 3-500 nm; preferably 30-100 nm, more preferably 50 nm. Preferably, catalyst B is titanium dioxide.

[0013] According to an embodiment of the present invention, the noble metal is 100% coated on catalyst A protruding from the surface of the film.

[0014] According to an embodiment of the present invention, the catalyst B1 is 100% coated on a noble metal.

[0015] This invention also provides a method for preparing the above-mentioned bifunctional film photocatalyst, the method comprising:

[0016] (S1) The catalyst A solution is mixed with the perfluorosulfonic acid resin solution, and the catalyst A is deposited on the membrane by filtration to obtain the catalyst A-membrane material;

[0017] Catalyst A is partially located in the pores of the membrane and partially protrudes from the surface of the membrane;

[0018] (S2) The noble metal is vapor-deposited onto the catalyst A-film material to obtain the noble metal-catalyst A-film material;

[0019] (S3) Deposit catalyst B onto the noble metal-catalyst A-film material from step (S2) to obtain the bifunctional film photocatalyst.

[0020] According to an embodiment of the present invention, the preparation method of cuprous oxide in catalyst A is as follows: a copper salt (e.g., copper chloride, copper sulfate, copper nitrate or copper bromide) is weighed and dissolved in 100-300 mL of water to obtain a 0.05-0.2 mmol / L solution. The pH is then adjusted to between 10 and 13, and the mixture is stirred at 300-1000 rpm for 0.5-3 h at 40-70 °C. Then, 1-3 mmol / L ascorbic acid solution is added dropwise, and the reaction is continued for 4 h. After cooling to room temperature, cuprous oxide powder is obtained by centrifugation or filtration and dried at 60 °C.

[0021] Preferably, the content of ascorbic acid solution is 5-15 mL.

[0022] According to an embodiment of the present invention, the preparation method of g-C3N4 in catalyst A is as follows: urea is weighed and ground into powder, and then placed in a muffle furnace for annealing at 550°C for 2 hours at a heating rate of 5°C / min to obtain g-C3N4.

[0023] Preferably, the powder is ground in a crucible, wherein the crucible is a 30mL alumina crucible, and the mass of the urea is 0.5-20g.

[0024] According to an embodiment of the present invention, in step (S1), the catalyst A solution is catalyst A dissolved in an organic solvent, wherein the organic solvent is selected from at least one of ethanol, isopropanol, n-hexane, chloroform, etc.

[0025] According to an embodiment of the present invention, in step (S1), the concentration of the catalyst A solution is 0.01-1 mg / mL, preferably 0.02-0.1 mg / mL.

[0026] According to an embodiment of the present invention, in step (S1), the concentration of the perfluorosulfonic acid resin solution is 1-8%.

[0027] According to an embodiment of the present invention, in step (S1), the mass-to-volume ratio of catalyst A to perfluorosulfonic acid resin solution is (0.5-4) mg:10 μL.

[0028] According to an embodiment of the present invention, step (S1) specifically involves: mixing catalyst A solution with perfluorosulfonic acid resin solution, and depositing catalyst A onto a membrane by means of vacuum filtration to obtain catalyst A-membrane material.

[0029] Preferably, after step (S1) is completed, the prepared product is dried.

[0030] As an exemplary embodiment of the present invention, step (S1) specifically includes:

[0031] Weigh 2 mg of catalyst A, disperse it in 50 mL of ethanol, add 20 μL of 5% perfluorosulfonic acid resin solution, then filter it onto a 3.5 cm diameter filter membrane, and then dry it at 60 °C to obtain catalyst A-membrane material.

[0032] According to an embodiment of the present invention, in step (S2), the vapor deposition is electron beam vapor deposition, for example, performed in a vapor deposition chamber.

[0033] According to an embodiment of the present invention, in step (S2), the power of the vapor deposition is 1.0-10.0%. By changing the vapor deposition power, the deposition rate of the noble metal is changed.

[0034] As an exemplary embodiment of the present invention, step (S2) specifically involves: preparation of the gold-catalyst A-film material: placing gold in a tungsten boat and the catalyst A-film material in a vapor deposition chamber, with the vapor deposition power being 1.0-10.0%. Preferably, the deposition rate is 3.0%, resulting in a metal deposition thickness of 30 nm.

[0035] As an exemplary embodiment of the present invention, step (S2) specifically involves: preparation of the silver-catalyst A-film material: placing silver in a tungsten boat and the catalyst A-film material in a vapor deposition chamber, with the vapor deposition power being 1.0-10.0%. Preferably, the deposition rate is 2.6%, resulting in a metal deposition thickness of 30 nm.

[0036] As an exemplary embodiment of the present invention, step (S2) specifically involves: preparation of platinum-catalyst A-film material: platinum is placed in a tungsten boat, and catalyst A-film material is placed in a vapor deposition chamber, with the vapor deposition power being 1.0-10.0%. Preferably, the deposition rate is 4.2%, resulting in a metal deposition thickness of 30 nm.

[0037] As an exemplary embodiment of the present invention, step (S2) specifically involves: preparation of palladium-catalyst A-film material: palladium is placed in a tungsten boat, and catalyst A-film material is placed in a vapor deposition chamber, with the vapor deposition power being 1.0-10.0%. Preferably, the deposition rate is 2.8%, resulting in a metal deposition thickness of 30 nm.

[0038] According to an embodiment of the present invention, in step (S3), catalyst B is deposited onto the noble metal-catalyst A-film material of step (S2) using atomic layer deposition technology.

[0039] According to an embodiment of the present invention, in step (S3), the deposition temperature is 80-250°C, preferably 120-240°C.

[0040] As an exemplary embodiment of the present invention, step (S3) specifically involves: when catalyst B is titanium dioxide: using atomic layer deposition (ALD) technology, with tetrakis(dimethylamino)titanium as the titanium source and a source bottle temperature of 75°C, depositing titanium dioxide onto the noble metal-catalyst A-film material from step (S2), wherein the deposition thickness of titanium dioxide is 50 nm. Preferably, the deposition temperature is 100-250°C. The source bottle refers to a bottle containing the titanium source.

[0041] As an exemplary embodiment of the present invention, step (S3) specifically involves: when catalyst B is zinc oxide: using atomic layer deposition technology, with diethylzinc as the zinc source, titanium dioxide is deposited onto the noble metal-catalyst A-film material of step (S2), wherein the deposition thickness of zinc oxide is 50 nm. Preferably, the deposition temperature is 80-220°C.

[0042] This invention also provides the application of the above-mentioned photocatalyst in photocatalytic carbon dioxide reduction and water oxidation. The beneficial effects of this invention are:

[0043] Compared with existing film-based photocatalysts, the photocatalyst of this invention exhibits better stability and catalytic performance, and avoids reactions between the oxidation and reduction ends, preventing mutual interference and contamination. In the presence of water and carbon dioxide, the photocatalyst of this invention can simultaneously reduce carbon dioxide to carbon monoxide and oxidize water to hydrogen peroxide, maintaining a catalytic performance of 370 μmol / g for 9 hours. -1 h -1 The CO production rate and selectivity were 96.5%; it was also able to generate 280 μmolg of CO. - 1 h -1 The selectivity for hydrogen peroxide is 86.5%. Furthermore, this catalyst has the advantages of flexible combination, simple preparation method, easy control of preparation conditions, and no pollution, making it valuable for research and application. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the preparation process of the cuprous oxide-silver-titanium dioxide-polytetrafluoroethylene film photocatalyst in Example 1 of the present invention, as well as a cross-sectional SEM image of the finished product and a mapping diagram of the corresponding elements.

[0045] Figure 2 These are X-ray diffraction patterns of the cuprous oxide-silver-titanium dioxide-polytetrafluoroethylene membrane photocatalyst prepared in Example 1 of the present invention, the cuprous oxide-polytetrafluoroethylene membrane photocatalyst in Comparative Example 2, and the cuprous oxide-silver-polytetrafluoroethylene membrane photocatalyst in Comparative Example 3.

[0046] Figure 3This is the photoelectron spectrum of the cuprous oxide-silver-titanium dioxide-polytetrafluoroethylene film photocatalyst prepared in Example 1 of this invention;

[0047] Figure 4 This is a transmission electron microscope image of the cuprous oxide-silver-titanium dioxide-polytetrafluoroethylene film photocatalyst prepared in Example 1 of this invention;

[0048] Figure 5 These are the photocatalytic performance graphs of the cuprous oxide-silver-titanium dioxide-polytetrafluoroethylene film photocatalyst prepared in Example 1 of this invention and the film catalysts in Comparative Examples 2-4.

[0049] Figure 6 This is a photocatalytic cycle diagram of the cuprous oxide-silver-titanium dioxide-polytetrafluoroethylene film photocatalyst prepared in Example 1 of this invention;

[0050] Figure 7 This is a schematic diagram illustrating the principle of photocatalytic carbon dioxide reduction and water oxidation of the photocatalyst of this invention. Detailed Implementation

[0051] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0052] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0053] Example 1

[0054] (1) Preparation of cuprous oxide: Weigh copper chloride and dissolve it in water to obtain a 0.1 mmol / L solution. Then adjust the pH to between 10 and 13 and stir at 500 rpm for half an hour at 50℃. Then add 2 mmol / L ascorbic acid solution dropwise with 1 / 10 of the volume of copper chloride solution. Continue the reaction for 4 hours and cool to room temperature. Centrifuge or filter to obtain cuprous oxide powder and dry at 60℃.

[0055] (2) Preparation of cuprous oxide-polytetrafluoroethylene membrane structure: 2 mg of cuprous oxide was weighed, dispersed in 50 mL of ethanol, and 20 μL of 5% perfluorosulfonic acid resin solution was added. The solution was then filtered onto a 3.5 cm diameter polytetrafluoroethylene filter membrane and dried at 60 °C to obtain the cuprous oxide-polytetrafluoroethylene membrane material. The loading density of cuprous oxide was 2 g / m³. 2 The pore size of the polytetrafluoroethylene membrane is 0.22 μm.

[0056] (3) Preparation of silver-cuprous oxide-polytetrafluoroethylene film material: The silver coating is achieved by electron beam evaporation. The silver is placed in a tungsten boat, while the cuprous oxide-polytetrafluoroethylene film material is placed in the evaporation chamber. The evaporation power is 2.6%, so that the silver deposition thickness is 30nm.

[0057] (4) Preparation of titanium dioxide-silver-cuprous oxide-polytetrafluoroethylene film material: Titanium dioxide was prepared by atomic layer deposition technology, with tetra(dimethylamino)titanium as the titanium source, source bottle temperature of 75℃ and deposition temperature of 200℃. Titanium dioxide was deposited on silver-cuprous oxide-polytetrafluoroethylene film (i.e. photocatalyst), wherein the deposition thickness of titanium dioxide was 50nm.

[0058] Figure 1 In the diagram, 'a' is a schematic diagram of the preparation process of the cuprous oxide-silver-titanium dioxide-polytetrafluoroethylene film photocatalyst in Example 1.

[0059] b is a cross-sectional SEM image of the photocatalyst;

[0060] cf is the mapping diagram for the corresponding element.

[0061] Example 2

[0062] (1) Preparation of g-C3N4: Weigh 10g of urea and grind it into powder. Then place it in a muffle furnace and anneal at 550℃ for 2h with a heating rate of 5℃ / min.

[0063] (2) Preparation of g-C3N4-polytetrafluoroethylene membrane structure: Weigh 2mg g-C3N4, disperse it in 50mL ethanol and add 20µL of 5% perfluorosulfonic acid resin solution, then filter it onto a polytetrafluoroethylene filter membrane with a diameter of 3.5cm, and then dry it at 60℃.

[0064] (3)(4) Same as (3)(4) in Example 1

[0065] Example 3

[0066] (1) Preparation of copper phthalocyanine-polytetrafluoroethylene membrane structure: Weigh 2 mg of copper phthalocyanine, disperse it in 50 mL of ethanol and add 20 μL of 5% perfluorosulfonic acid resin solution, then filter it onto a polytetrafluoroethylene filter membrane with a diameter of 3.5 cm, and then dry it at 60 °C.

[0067] (2)(3) Same as (3)(4) in Example 1

[0068] Example 4

[0069] (1)(2) Same as (1)(2) in Example 1

[0070] (3) Preparation of gold-cuprous oxide-polytetrafluoroethylene film material: The gold coating is achieved by electron beam evaporation.

[0071] Gold was placed in a tungsten boat, and cuprous oxide-PTFE film material was placed in a vapor deposition chamber, with a vapor deposition power of 3%. The gold deposition thickness was 30 nm.

[0072] (4) Same as (4) in Example 1.

[0073] Example 5

[0074] (1)(2)(3) Same as (1)(2)(3) in Example 1

[0075] (4) Preparation of zinc oxide-silver-cuprous oxide-polytetrafluoroethylene membrane material: Zinc oxide was prepared by atomic layer deposition technology, and titanium dioxide was deposited on the silver-cuprous oxide-polytetrafluoroethylene membrane material with diethyl zinc as zinc source. The deposition thickness of zinc oxide was 50 nm and the deposition temperature was 150 °C.

[0076] Comparative Example 1

[0077] (1) Same as (1) in Example 1.

[0078] (2) Preparation of cuprous oxide-cellulose acetate membrane structure: Weigh 2 mg of cuprous oxide, disperse it in 50 mL of ethanol and add 20 μL of 5% perfluorosulfonic acid resin solution, then filter it onto a cellulose acetate filter membrane with a diameter of 3.5 cm, and then dry it at 60 °C.

[0079] (3)(4) Same as (3)(4) in Example 1.

[0080] (5) Preparation of mixed particle / polytetrafluoroethylene membrane structure: The titanium dioxide-silver-cuprous oxide-cellulose acetate membrane prepared above was dissolved in 50 mL of acetone and filtered again onto a polytetrafluoroethylene filter membrane, and then dried at 60 °C.

[0081] Comparative Example 2

[0082] For cuprous oxide-polytetrafluoroethylene membrane catalysts

[0083] (1) Same as (1) in Example 1.

[0084] (2) Same as (2) in Example 1.

[0085] Comparative Example 3

[0086] For cuprous oxide-silver catalyst-polytetrafluoroethylene membrane catalyst

[0087] (1) Same as (1) in Example 1.

[0088] (2) Same as (2) in Example 1.

[0089] (3) Same as (3) in Example 1.

[0090] Comparative Example 4

[0091] For titanium dioxide-polytetrafluoroethylene membrane catalysts

[0092] Preparation of the titanium dioxide-polytetrafluoroethylene (PTFE) membrane structure: 2 mg of titanium dioxide was weighed, dispersed in 50 mL of ethanol, and 20 μL of 5% perfluorosulfonic acid resin solution was added. The solution was then filtered onto a 3.5 cm diameter PTFE filter membrane and dried at 60 °C to obtain the cuprous oxide-PTFE membrane material. The cuprous oxide loading density was 2 g / m³. 2 The pore size of the polytetrafluoroethylene membrane is 0.22 μm.

[0093] 1. The titanium dioxide-silver-cuprous oxide-polytetrafluoroethylene membrane photocatalyst in Example 1, the cuprous oxide-polytetrafluoroethylene membrane photocatalyst in Comparative Example 2, and the cuprous oxide-silver-polytetrafluoroethylene membrane photocatalyst in Comparative Example 3 (i.e., respectively) Figure 2 The composition and morphology of Cu2O-Ag-TiO2, Cu2O and Cu2O-Ag were determined.

[0094] The crystal phase structures of the photocatalyst prepared in Example 1, the cuprous oxide-polytetrafluoroethylene film catalyst in Comparative Example 2, and the cuprous oxide-silver-polytetrafluoroethylene film catalyst in Comparative Example 3 were analyzed using an X-ray diffractometer from Rigaku, Japan. The X-ray target was Cu Kα, the voltage was 40 kV, the current was 100 mA, the step size was 0.2°, and the scanning range was 5°–80°. The X-ray diffraction patterns are shown below. Figure 2 As shown, however, no Ag and TiO2 peaks were observed in the X-ray diffraction pattern of the titanium dioxide-silver-cuprous oxide-polytetrafluoroethylene film photocatalyst because both are amorphous and amorphous.

[0095] Thermo-Fisher photoelectron spectroscopy was used for detection, and carbon peak correction (284.8 eV) was performed. The spectrum fitting is as follows: Figure 3 As shown, where Figure 3 In the image, a represents the full-range spectral lines of the titanium dioxide-silver-cuprous oxide-polytetrafluoroethylene film photocatalyst; b, c, and d are the fine photoelectron spectra of Cu, Ti, and Ag, respectively. Figure 3 Taking b as an example, the peak positions of Cu on the left and right sides represent different spectral terms in the fine spectrum of the photoelectron energy spectrum of copper (Cu 2p). 3 / 2 932.1 eV, Cu 2p 1 / 2(952.0 eV). In addition, the peaks at 458.5 eV and 464.5 eV, and the peaks at 368.2 eV and 374.2 eV, prove the presence of elemental silver and titanium dioxide. At the same time, photoelectron spectroscopy and Auger spectroscopy prove the presence of monovalent copper, proving the successful preparation of the titanium dioxide-silver-cuprous oxide-polytetrafluoroethylene film.

[0096] 2. Transmission electron microscopy image of the titanium dioxide-silver-cuprous oxide-polytetrafluoroethylene film photocatalyst in Example 1.

[0097] The morphology of the titanium dioxide-silver-cuprous oxide-polytetrafluoroethylene film photocatalyst prepared in Example 1 was observed using an HT7700 transmission electron microscope. The transmission electron microscope image is shown below. Figure 4 As shown, dispersed titanium dioxide-silver-cuprous oxide nanoparticles were obtained by ultrasound. Figure a shows aggregated titanium dioxide-silver-cuprous oxide nanoparticles; Figure b is a magnified view of Figure a; Figures c and d are further magnified views of the corresponding boxes in the lower and upper left corners of Figure b, respectively. That is, Figure c is a magnified view of the red box in Figure b, and Figure d is a magnified view of the yellow box in Figure b. Figure 4 As can be seen, the silver layer is approximately 30 nm thick in the middle, while the outer layer is titanium dioxide approximately 50 nm thick. Furthermore, because the loading was directionally deposited from one side, there is no signal of silver or titanium dioxide on the other side of the cuprous oxide layer, as shown in Figure d.

[0098] 3. Study on the performance and stability of the titanium dioxide-silver-cuprous oxide-polytetrafluoroethylene film photocatalyst in Example 1

[0099] At 300mw / cm 2 Under full light illumination, the performance of the photocatalyst was verified using pure water and carbon dioxide as reactants in both reactions. The photocatalytic performance was measured in a 167 mL reactor under ambient pressure and room temperature conditions. The photocatalyst from Example 1 and the catalysts from Comparative Examples 2-4 (i.e., corresponding to...) were respectively... Figure 5 The titanium dioxide film photocatalyst (Cu₂O-Ag-TiO₂, Cu₂O, Cu₂O-Ag, and TiO₂) was placed at the bottom of the reactor, and 17 mL of water was added to submerge the bottom layer, allowing the titanium dioxide film photocatalyst to float on the water surface with its side facing down. Carbon dioxide gas was then introduced for 30 minutes, followed by irradiation. The gaseous products were detected using FID and TCD detectors, while the liquid products were detected using UV-Vis spectroscopy. The test results are as follows: Figure 5 As shown.

[0100] In addition, a cycle performance experiment was conducted on the photocatalyst in Example 1. The specific implementation method is as follows: after one performance test of the photocatalyst in Example 1, the sequential cycle was considered to be completed; then, after cleaning and drying the reactor and catalyst, another performance test was conducted, which was considered to be the second cycle; the above cycles were performed a total of five times, and the products were tested respectively. Figure 6 The CO(2) obtained after performing five cycles of Example 1 Figure 6 (left) and hydrogen peroxide products ( Figure 6 (Right) Generation rate (left axis, black) and selectivity (right axis, red) plots.

[0101] from Figure 5 and Figure 6 It can be seen that the titanium dioxide-silver-cuprous oxide-polytetrafluoroethylene membrane photocatalyst of the present invention has significant advantages in catalytic performance and selectivity, with a CO yield of 370 μmol / g. -1 h -1 The selectivity was 96.5%; it was also able to generate 280 μmolg. -1 h -1 The selectivity for hydrogen peroxide was 86.5%. This is because the film-form photocatalyst takes into account the reaction effects on both sides and achieves reaction optimization on both sides.

[0102] Meanwhile, the cyclic test showed that the overall reaction performance did not decrease significantly after five cycles, which also demonstrates the stability of the bifunctional film photocatalyst of the present invention.

[0103] The embodiments of the present invention have been described above by way of example. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A bifunctional film-like photocatalyst, characterized in that, It includes a membrane, a catalyst A loaded in the pores of the membrane, and a portion of the catalyst A loaded in the pores protruding from the surface of the membrane, a noble metal coating on the catalyst A protruding from the surface of the membrane, and a catalyst B coating on the noble metal. Wherein, catalyst A is selected from at least one of cuprous oxide, copper phthalocyanine, cobalt phthalocyanine, nickel phthalocyanine and g-C3N4; The catalyst B is selected from at least one of titanium dioxide, bismuth vanadate, zinc oxide, bismuth tungstate, and tungsten trioxide.

2. The photocatalyst according to claim 1, characterized in that, Part of the catalyst A is located in the pores of the membrane, and part of it protrudes from the surface of the membrane.

3. The photocatalyst according to claim 1, characterized in that, The catalyst A has a loading density of 0.05-10 g / m³. 2 .

4. The photocatalyst according to claim 1, characterized in that, The membrane is selected from at least one of polytetrafluoroethylene membrane, polyvinylidene fluoride membrane, cellulose acetate membrane, nylon filter membrane, and polyethersulfone membrane.

5. The photocatalyst according to claim 1, characterized in that, The membrane has a pore size of 0.1-1 micrometer.

6. The photocatalyst according to claim 1, characterized in that, The precious metal is selected from at least one of gold, silver, platinum and palladium.

7. The photocatalyst according to claim 1, characterized in that, The thickness of the precious metal is 3-300 nm.

8. The photocatalyst according to claim 1, characterized in that, The thickness of catalyst B is 3-500 nm.

9. The photocatalyst according to claim 1, characterized in that, The precious metal is 100% coated on catalyst A, which protrudes from the surface of the membrane.

10. The photocatalyst according to claim 1, characterized in that, The catalyst B is 100% coated with a precious metal.

11. A method for preparing the photocatalyst according to any one of claims 1-10, characterized in that, The method includes: (S1) The catalyst A solution is mixed with the perfluorosulfonic acid resin solution, and the catalyst A is deposited on the membrane by filtering the mixture onto the membrane to obtain the catalyst A-membrane material; Catalyst A is partially located in the pores of the membrane and partially protrudes from the surface of the membrane; (S2) The noble metal is vapor-deposited onto the catalyst A-film material to obtain the noble metal-catalyst A-film material; (S3) Deposit catalyst B onto the noble metal-catalyst A-film material from step (S2) to obtain the bifunctional film photocatalyst.

12. The method according to claim 11, characterized in that, In step (S1), the catalyst A solution is catalyst A dissolved in an organic solvent, wherein the organic solvent is selected from at least one of ethanol, isopropanol, n-hexane and chloroform.

13. The method according to claim 11, characterized in that, In step (S1), the concentration of the catalyst A solution is 0.01-1 mg / mL.

14. The method according to claim 11, characterized in that, In step (S1), the concentration of the perfluorosulfonic acid resin solution is 1-8%.

15. The method according to claim 11, characterized in that, In step (S1), the mass-to-volume ratio of catalyst A to perfluorosulfonic acid resin solution is (0.5-4) mg: 10 μL.

16. The method according to claim 11, characterized in that, In step (S3), catalyst B is deposited onto the noble metal-catalyst A-film material from step (S2) using atomic layer deposition technology; The deposition temperature is 80-250℃.

17. The use of the photocatalyst according to any one of claims 1-10 in photocatalytic carbon dioxide reduction and water oxidation.

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