Gold / nickel-tungsten oxide dual-plasmon heterojunction photocatalyst as well as preparation method and application thereof

Abstract

The invention discloses a gold / nickel-tungsten oxide dual-plasmon heterojunction photocatalyst as well as a preparation method and application thereof, and relates to the technical field of nano composite materials and photocatalysis. The monatomic nickel surface modified plasmon W18O49 nanowire is synthesized through a combined dissolution heat method and a dipping-thermal reduction process; then, gold nanoparticles are loaded on the plasmon W18O49 nanowire by adopting a method of reducing chloroauric acid in situ through ascorbic acid, and the double-plasmon heterojunction material is constructed. The gold / nickel-tungsten oxide dual-plasmon heterojunction material is prepared by adopting the method disclosed by the invention. Under illumination, interface hot spots generated in the heterojunction can promote generation and separation of hot electrons in the double-plasmon heterojunction, and the concentration of catalytic activity hot carriers on the surface of the catalyst is increased; meanwhile, under the synergistic effect of double reaction active sites on the constructed Ni-Au interface, efficient and high-selectivity photocatalytic reduction of CO2 can be realized to prepare C2H6 chemicals.

Description

Technical Field

[0001] This invention relates to the fields of nanocomposite materials and photocatalysis, specifically to a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst, its preparation method, and its application. Background Technology

[0002] Photocatalytic CO2 reduction technology aims to mimic natural photosynthesis, utilizing solar energy to convert CO2 and H2O into high-value fuels and chemicals. Current research mainly focuses on the synthesis of C1 products (such as CO and CH4), and significant progress has been made in the selective control of these products. However, C2O, with its higher energy density and chemical value, is still a promising area for further research. 2+ The synthesis of products (such as C2H4, C2H6, etc.) still faces severe challenges. The bottleneck mainly stems from the complexity of the multi-step reaction pathway: not only is the efficient generation and stabilization of C1 intermediates (*CO, *CHO) required, but more importantly, the high C-C coupling energy barrier must be overcome, and precise control of subsequent hydrogenation steps must be achieved.

[0003] Nonmetallic plasmonic tungsten oxide (W 18 O 49 Due to its unique full-spectrum response and surface plasmon resonance (SPR) effect, it exhibits excellent photocatalytic CO2 reduction potential. However, W 18 O 49 Photocatalytic CO2 reduction to C 2+ Two key issues remain in the application of the product: (1) low concentration of catalytically active hot carriers; and (2) lack of effective reactive sites to reduce the energy barrier of C–C coupling reaction.

[0004] Therefore, enhance W 18 O 49 The generation and separation of intermediate-thermal carriers, and the construction of synergistic reactive sites, are crucial for achieving efficient photocatalytic CO2 reduction to C2. 2+ The key to the product. Summary of the Invention

[0005] The purpose of this invention is to provide a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst, its preparation method, and its application, which solves the above-mentioned problems. The formed interfacial "hot spots" can enhance the generation and separation of hot electrons in the gold / nickel-tungsten oxide dual plasmon heterojunction and construct interfacial synergistic reactive sites, thereby achieving efficient and highly selective photocatalytic CO2 reduction to ethane (C2H6) chemicals.

[0006] To achieve the above objectives, this invention discloses a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst, comprising a plasmon W as a substrate. 18 O 49 Nanowires, and metal-active units constructed in situ on their surface; The metal active units include gold and nickel, with the gold element supported on W in the form of nanoparticles. 18 O 49 On the surface of the nanowires, nickel is loaded onto W in single-atom form. 18 O 49 On the surface of the nanowires, a gold / nickel-tungsten oxide dual plasmon heterostructure is formed, constituting a dual-plasmon heterostructure system. The constructed Ni-Au interface dual reactive sites have a synergistic effect. Under illumination, the interfacial "hot spots" generated in the heterostructure can promote the generation and separation of hot electrons in the dual plasmon heterostructure, increasing the concentration of catalytically active hot carriers on the catalyst surface.

[0007] Preferably, the size of the gold nanoparticles is 50-60 nm.

[0008] Preferably, the mass ratio of gold nanoparticles to single-atom nickel is (0.9-6):1.

[0009] Preferred, dual plasmon Au / Ni-W 18 O 49 Heterojunctions possess strong ultraviolet-visible-near-infrared light absorption capabilities and localized surface plasmon resonance effects.

[0010] This invention also provides a method for preparing the above-mentioned gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst, comprising the following steps: Step (1) Synthesize single-atom nickel surface-modified plasmons W by a solution thermal method and an impregnation-thermal reduction process. 18 O 49 Nanowires; Step (2) involves loading gold nanoparticles onto plasmon resonance W using the in-situ reduction of chloroauric acid with ascorbic acid. 18 O 49 A gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst was obtained on nanowires.

[0011] Preferably, step (1) specifically includes the following steps: (1-1) Tungsten hexachloride was added to anhydrous ethanol solution and stirred until dissolved to obtain a precursor solution; the above precursor solution was added to a stainless steel reactor lined with polytetrafluoroethylene and subjected to solvothermal treatment to obtain plasmon W. 18 O 49 Nanowires; (1-2) Plasmon W 18 O 49 Nanowire powder was ultrasonically dispersed in anhydrous ethanol containing nickel salt to obtain a premix. After continuous stirring for a period of time, the sample was centrifuged and dried, and then thermally reduced in a 10% H2 / Ar mixed gas to obtain a single-atom Ni-modified plasmon W. 18O 49 Nanowires.

[0012] Preferably, in step (1-1), the concentration of tungsten hexachloride in anhydrous ethanol is 3-5 mg / mL, the temperature of the heat of solution reaction is 160-190 °C, and the reaction time is 10-18 hours; In steps (1-2), in the premixed solution, Ni in the nickel salt reacts with plasmons W. 18 O 49 The mass ratio of nanowires is 0.1%-0.8%, the thermal reduction temperature is 120-150 ℃, the time is 1-2 hours, and the nickel salt is any one or more of nickel chloride and nickel nitrate.

[0013] Preferably, step (2) specifically includes the following steps: modifying the prepared single-atom Ni surface with plasmon W 18 O 49 Nanowires were ultrasonically dispersed in anhydrous ethanol, and ascorbic acid reducing agent was added and stirred for 30 minutes. Then, chloroauric acid ethanol solution was added dropwise to the above solution to carry out the reduction reaction. After centrifugation and drying, gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst was obtained.

[0014] Preferably, the plasmon W is modified with a single-atom Ni surface. 18 O 49 The concentration of nanowires in ethanol was 1-3 mg / mL; ascorbic acid reducing agent was added to a concentration of 4-8 mg / mL; Au in the added chloroauric acid reacted with plasmon resonance W. 18 O 49 The mass ratio of nanowires is 0.3%-2.0%; the stirring time for the in-situ reduction of chloroauric acid is 1-3 hours.

[0015] The gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst provided by this invention can be applied to the photocatalytic reduction of CO2 to produce C2H6, CH4 and CO.

[0016] Preferably, the selectivity for photocatalytic reduction of CO2 to C2H6 is ≥72%.

[0017] Therefore, the present invention employs the above-mentioned gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst, its preparation method, and its application, which have the following beneficial effects: (1) This invention provides a dual plasmon heterojunction photocatalyst for photocatalytic CO2 reduction, comprising plasmons W modified on the surface of a single-atom Ni. 18 O 49Nanowires and plasmonic Au nanoparticles are constructed in close contact. In the dual plasmonic heterojunction system, the "hot spots" formed at the interface amplify the local electric field, enhancing the light absorption and hot carrier generation of the dual plasmonic heterojunction. The high concentration of active hot carriers facilitates the photocatalytic reduction of CO2 to C. 2+ Products. The high concentration of active hot electrons generated by the synergistic effect of the active sites in single-atom Ni and Au nanoparticles enables highly efficient photocatalytic reduction of CO2 to C2H6 chemicals.

[0018] (2) The gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst prepared by this invention can efficiently and selectively reduce CO2 to C2H6 at room temperature and pressure, which is in line with the sustainable energy development strategy and has good application prospects. In addition, the catalyst has a simple synthesis process, inexpensive and readily available raw materials, and can be repeatedly recycled. It is an ideal material to replace traditional precious metal catalysts and realize large-scale CO2 resource utilization, and has important value in the field of renewable energy.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 These are Fourier transform extended X-ray absorption fine structure characterization images of the sample prepared in Example 1 of this invention and the reference sample Ni foil and NiO; Figure 2 X-ray diffraction patterns of the samples prepared in Examples 3-8 of this invention; Figure 3 This is a microscopic morphology image of the sample prepared in Example 6 of the present invention, where a is Au. 1.2 / Ni 0.32 -W 18 O 49 Transmission electron microscope image of the heterojunction, b is Au 1.2 / Ni 0.32 -W 18 O 49 High-resolution transmission electron microscope image of a heterojunction; Figure 4 The UV-Vis-NIR diffuse reflectance spectra of the synthesized samples in Examples 1 and 6 of this invention are shown below. Figure 5 The graphs show the photocatalytic CO2 reduction to CH4, CO and C2H6 performance and C2H6 product selectivity of the samples synthesized in Examples 3-8 of Application Example 1 of this invention. Figure 6 The Au synthesized in Example 6 is used in Application Example 1 of this invention. 1.2 / Ni 0.32 -W 18 O49 In-situ infrared spectrum of the photocatalytic CO2 reduction process in the heterojunction sample; Figure 7 The Au synthesized in Example 6 is used in Application Example 2 of this invention. 1.2 / Ni 0.32 -W 18 O 49 Performance diagram of five photocatalytic CO2 reduction cycles of the heterojunction sample. Detailed Implementation

[0021] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0022] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. These other embodiments are also covered within the scope of protection of this invention.

[0023] This invention provides a method for preparing plasmonic tungsten oxide with a single-atom nickel surface modification. Tungsten hexachloride is added to anhydrous ethanol solution and stirred until dissolved to obtain a precursor solution. The precursor solution is then added to a stainless steel reactor lined with polytetrafluoroethylene (PTFE) and subjected to solvothermal treatment to obtain plasmonic W. 18 O 49 Nanowires. To incorporate plasmon resonance (W) 18 O 49 Nanowire powder was ultrasonically dispersed in anhydrous ethanol containing nickel salt and stirred continuously for a period of time. The sample was then centrifuged, dried, and thermally reduced in a 10% H₂ / Ar mixed gas to obtain single-atom Ni-modified plasmon W. 18 O 49 Nanowires.

[0024] In the above-mentioned method for preparing plasmon tungsten oxide with a single-atom nickel surface modification, the concentration of tungsten hexachloride in anhydrous ethanol is 3-5 mg / mL, the temperature of the heat of dissolution reaction is 160-190 ℃, and the reaction time is 10-18 hours; the Ni in the added nickel salt reacts with the plasmon W... 18 O 49 The mass ratio of nanowires is 0.1%-0.8%, the thermal reduction temperature is 120-150 ℃, and the time is 1-2 hours.

[0025] This invention also provides a method for preparing a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst, comprising a plasmon W as a substrate.18 O 49 Nanowires, and metallic active units constructed in situ on their surface; the metallic active units include gold and nickel elements, with the gold element loaded onto W in the form of nanoparticles. 18 O 49 On the surface of the nanowires, nickel is loaded onto W in single-atom form. 18 O 49 A dual plasmon heterostructure is formed on the surface of the nanowires.

[0026] Plasmon W prepared by surface modification of single-atom Ni 18 O 49 Nanowires were ultrasonically dispersed in anhydrous ethanol, and a certain amount of ascorbic acid reducing agent was added and stirred for 30 minutes. A certain amount of chloroauric acid ethanol solution was added dropwise to the above solution to carry out the reduction reaction. The suspension was centrifuged and dried to obtain a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst.

[0027] In the above-mentioned preparation method of a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst, the plasmon W modified on the surface of single-atom Ni... 18 O 49 The concentration of nanowires in ethanol was 1-3 mg / mL; the concentration of ascorbic acid reducing agent was 2-6 mg / mL; Au in the added chloroauric acid and plasmon resonances modified with single-atom Ni were also present. 18 O 49 The mass ratio of nanowires is 0.3%-2.0%; the stirring time for the in-situ reduction of chloroauric acid is 1-3 hours.

[0028] A gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst was obtained using the above preparation method, with elemental Ni supported in an atomically dispersed form on W 18 O 49 The obtained dual plasmon Au / Ni-W on the nanowire surface 18 O 49 The heterojunction exhibits strong UV-Vis-NIR light absorption and the SPR effect. The loaded Au is in the form of nanoparticles with a particle size of 50-60 nm.

[0029] This gold / nickel-tungsten oxide dual plasmon heterojunction is applied to photocatalytic CO2 reduction, where the selectivity for photocatalytic reduction of CO2 to C2H6 is ≥72%.

[0030] The specific method for the photocatalytic CO2 reduction experiment is as follows: the catalyst is ultrasonically dispersed in water and dripped onto quartz fiber paper for drying; after it is completely dry, the quartz fiber paper covered with the catalyst is placed in the reactor, high-purity CO2 gas is introduced and a small amount of deionized water is added, and a xenon lamp is used as a simulated sunlight to carry out the photocatalytic CO2 reduction experiment.

[0031] In the application of the aforementioned gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst in photocatalytic CO2 reduction, the amount of photocatalyst used is 3-8 mg, and the area of ​​the quartz fiber paper is 7-15 cm². 2 Add 0.1-0.2 mL of deionized water.

[0032] The light source is a 300 W xenon lamp with a full spectrum range of 200~1100 nm and a light intensity of 150~450 mW / cm². 2 .

[0033] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0035] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. These other embodiments are also covered within the scope of protection of this invention.

[0036] Example 1 This embodiment provides a method for preparing plasmonic tungsten oxide with a single-atom nickel surface modification, specifically including the following steps: (1) 120 mg of tungsten hexachloride powder was dissolved in 32 mL of anhydrous ethanol by stirring. The precursor solution was then transferred to a 50 mL stainless steel autoclave lined with polytetrafluoroethylene and reacted solvothermically at 185 °C for 13 hours. After cooling to room temperature, the resulting precipitate was centrifuged, washed with ethanol, and dried under vacuum to obtain the plasmon W. 18 O 49 Nanowires.

[0037] (2) 50 mg of plasmon W 18 O 49Nanowires were ultrasonically dispersed in 25 mL of anhydrous ethanol containing 0.8 mg of nickel chloride hexahydrate, and the mixture was stirred for 5 hours before centrifugation and drying. Plasmon resonances with adsorbed nickel species were then... 18 O 49 The powder was placed in a tube furnace and heated to 135 °C in a 10% H2 / Ar mixed gas, and held at that temperature for 1.5 hours. After cooling, uniatomic nickel-modified plasmonic tungsten oxide, i.e., Ni, was obtained. 0.32 -W 18 O 49 .

[0038] Example 2 This embodiment provides a method for preparing plasmonic tungsten oxide with a single-atom nickel surface modification, which is the same as in Example 1, except that in step (2), 50 mg of plasmonic W 18 O 49 Nanowires were ultrasonically dispersed in 25 mL of anhydrous ethanol containing 1.7 mg of nickel chloride hexahydrate.

[0039] Example 3 This embodiment provides a method for preparing a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst, including the following steps: (1) Prepare plasmonic tungsten oxide with single-atom nickel surface modification, the preparation method is the same as in Example 1; (2) 30 mg of Ni single-atom surface-modified W 18 O 49 Nanowire powder was ultrasonically dispersed in 20 mL of anhydrous ethanol, and 60 mg of ascorbic acid was added and stirred until dissolved. Then, an ethanol solution containing 0.155 mg of chloroauric acid was added dropwise to the dispersion suspension, and stirring continued for 2 hours until the reduction reaction was complete. The suspension was centrifuged, the sample was collected, and vacuum dried at 65 °C for 3 hours to obtain a gold nanoparticle-supported nickel single-atom surface-modified tungsten oxide nanowire dual plasmon heterostructure, namely Au / Ni-W. 18 O 49 The tungsten oxide nanowires are named according to the theoretical mass ratio of Au-loaded to nickel-loaded single-atom surface-loaded tungsten oxide nanowires. In this embodiment, the Au-loaded and nickel-loaded single-atom-loaded W... 18 O 49 The theoretical mass ratio of nanowires is 0.3%, i.e., Au. 0.3 / Ni 0.32 -W 18 O 49 .

[0040] Example 4 This embodiment provides a method for preparing a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst. The steps are the same as in Example 3, except that in this embodiment, Au and nickel single-atom-loaded W are used. 18 O 49 The theoretical mass ratio of nanowires is 0.6%, i.e., Au. 0.6 / Ni 0.32 -W 18 O 49 .

[0041] Example 5 This embodiment provides a method for preparing a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst. The steps are the same as in Example 3, except that in this embodiment, Au and nickel single-atom-loaded W are used. 18 O 49 The theoretical mass ratio of nanowires is 0.9%, i.e., Au. 0.9 / Ni 0.32 -W 18 O 49 .

[0042] Example 6 This embodiment provides a method for preparing a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst. The steps are the same as in Example 3, except that in this embodiment, Au and nickel single-atom-loaded W are used. 18 O 49 The theoretical mass ratio of nanowires is 1.2%, i.e., Au. 1.2 / Ni 0.32 -W 18 O 49 .

[0043] Example 7 This embodiment provides a method for preparing a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst. The steps are the same as in Example 3, except that in this embodiment, Au and nickel single-atom-loaded W are used. 18 O 49 The theoretical mass ratio of nanowires is 1.5%, i.e., Au. 1.5 / Ni0.32-W 18 O 49 .

[0044] Example 8 This embodiment provides a method for preparing a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst. The steps are the same as in Example 3, except that in this embodiment, Au and nickel single-atom-loaded W are used. 18 O 49 The theoretical mass ratio of nanowires is 1.8%, i.e., Au. 1.8 / Ni0.32 -W 18 O 49 .

[0045] Figure 1 Ni foil, NiO reference sample and Ni prepared in Example 1 0.32 -W 18 O 49 Fourier transform extended X-ray absorption fine structure diagram, showing the synthesized Ni 0.32 -W 18 O 49 The presence of only Ni-O bonds and the absence of any Ni-Ni bonds proves that Ni is loaded onto the plasmon W in a single-atom form. 18 O 49 Surface.

[0046] Ni with different Au loadings synthesized in Examples 3-8 0.32 -W 18 O 49 X-ray diffraction analysis was performed on a dual plasmon heterostructure. For example... Figure 2 As shown, all double plasmon heterojunction samples exhibit only W 18 O 49 The diffraction peaks of the synthesized Au were observed (JCPDS: 71-2450), while no diffraction peaks of Au were found. This is likely due to the low Au loading, making it difficult to resolve using XRD techniques. Regarding the synthesized Au... 1.2 / Ni 0.32 -W 18 O 49 The dual plasmon heterostructure was characterized by transmission electron microscopy, such as... Figure 3 As shown in Figure a, the Au nanoparticles have a size of approximately 55 nm and are tightly attached to the Ni. 0.32 -W 18 O 49 Nanowire surfaces. For example... Figure 3 As shown in b, Au 1.2 / Ni 0.32 -W 18 O 49 High-resolution transmission electron microscopy images of the heterostructure show two lattice spacings of 0.235 nm and 0.38 nm, corresponding to the (111) crystal plane of Au and Ni, respectively. 0.32 -W 18 O 49 The (010) crystal plane, this result fully demonstrates the successful preparation of the double plasmon heterostructure.

[0047] The W synthesized in Examples 1 and 6 18 O 49 Ni 0.32 -W18 O 49 and Au 1.2 / Ni 0.32 -W 18 O 49 Ultraviolet-visible-near-infrared diffuse reflectance spectroscopy analysis was performed on a dual plasmon heterostructure. For example... Figure 4 As shown, W 18 O 49 It exhibits two absorption characteristics: intrinsic band absorption and SPR absorption; Ni 0.32 -W 18 O 49 Showing slightly lower than W 18 O 49 The SPR absorption of Au is likely due to a slight decrease in its free electron concentration caused by the synthesis process. 1.2 / Ni 0.32 -W 18 O 49 In addition to exhibiting Ni 0.32 -W 18 O 49 In addition to its light absorption characteristics, an absorption bulge appeared at 540 nm, corresponding to the SPR absorption of Au nanoparticles, due to its interaction with Ni. 0.32 -W 18 O 49 The overlap of light absorption does not highlight its absorption characteristics, but it still proves the successful preparation of the dual plasmon heterostructure.

[0048] Application Example 1 This application example demonstrates the use of a gold / nickel-tungsten oxide dual plasmon heterojunction in photocatalytic CO2 reduction, specifically including the following steps: 5 mg of Au / Ni prepared in Examples 3-8 with different Au loadings were used. 0.32 -W 18 O 49 The heterojunction photocatalysts were ultrasonically dispersed in 0.3 mL of deionized water and then uniformly drop-coated onto a surface with an area of ​​10 cm². 2 The photocatalyst-coated glass fiber paper was placed on the glass fiber paper. After drying, the glass fiber paper was placed into a 150 mL reactor and sealed with a thick quartz lid. Before the reaction, high-purity CO2 gas was continuously passed through the reactor for about 20 minutes, and 0.2 mL of water was added to the bottom of the reactor. A 300W xenon lamp was used as a simulated sunlight source (wavelength 200-1100 nm, light intensity 300 mW / cm²). 2 The photocatalytic CO2 reduction experiment was conducted, with a reaction time of 180 minutes. During this period, gaseous products were collected every 30 minutes and monitored and analyzed using gas chromatography.

[0049] The measured yields of photocatalytic CO2 reduction to CH4, CO, and C2H6 are as follows: Figure 5 As shown, the constructed gold / nickel-tungsten oxide dual plasmon heterostructures can all achieve photocatalytic CO2 reduction to C2H6, and the C2H6 yield shows a trend of first increasing and then decreasing with the increase of Au nanoparticle loading. Among them, Au... 1.2 / Ni 0.32 -W 18 O 49 The heterojunction exhibited the best photocatalytic CO2 reduction performance, with yields of 7.15, 2.67, and 25.41 µmol / g / h for CH4, CO, and C2H6, respectively. -1 ·h -1 The selectivity of the corresponding C2H6 product is as high as 72.13%. Furthermore, such as... Figure 6 As shown, Au 1.2 / Ni 0.32 -W 18 O 49 In-situ infrared spectroscopy results of photocatalytic CO2 reduction in heterojunctions showed that with increasing illumination time, the sample exhibited a significant infrared peak of the *COCHO intermediate, which proves that Au... 1.2 / Ni 0.32 -W 18 O 49 Heterojunctions can enable CC coupling and C2H6 generation in photocatalytic CO2 reduction.

[0050] Application Example 2 This application example provides a cyclic experiment of a gold / nickel-tungsten oxide dual plasmon heterojunction in photocatalytic CO2 reduction. Following the experimental protocol in Application Example 1, the Au prepared in Example 6... 1.2 / Ni 0.32 -W 18 O 49 The heterojunction was first subjected to a photocatalytic CO2 reduction experiment. After the reaction, the reactor was purged with high-purity CO2 gas for 30 minutes to remove the reduction products from the first round of reaction. The experimental scheme in Example 1 was repeated for a total of five photocatalytic CO2 reduction experiments. The yields of CH4, CO, and C2H6 over time in the five cycles are shown in the figure below. Figure 7 As shown, the yields of all photocatalytic CO2 reduction products did not decrease significantly, indicating that the catalyst possesses good stability in photocatalytic CO2 reduction and can be repeatedly recycled.

[0051] In summary, this invention provides a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst, its preparation method, and its application, comprising plasmons W modified from a single-atom nickel surface. 18O 49 This catalyst is constructed by close contact between nanowires and Au nanoparticles. Under illumination, the interfacial "hot spots" generated in the gold / nickel-tungsten oxide dual plasmon heterojunction promote the generation and separation of hot electrons within the dual plasmon heterojunction, increasing the concentration of catalytically active hot carriers on the photocatalyst surface. Simultaneously, the synergistic dual reactive sites at the constructed Ni-Au interface enable highly efficient and selective photocatalytic reduction of CO2 to C2H6. Therefore, this catalyst has significant application value in the fields of CO2 conversion to multi-carbon fuels or chemicals and efficient solar energy utilization.

[0052] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and does not limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst, characterized in that, Including plasmons W as the basis 18 O 49 Nanowires, and metal-active units constructed in situ on their surface; The metal active units include gold and nickel, with the gold element supported on W in the form of nanoparticles. 18 O 49 On the surface of the nanowires, nickel is loaded onto W in single-atom form. 18 O 49 Gold / nickel-tungsten oxide double plasmon heterostructures are formed on the surface of nanowires.

2. The gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst according to claim 1, characterized in that, The size of the gold nanoparticles is 50-60 nm.

3. The gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst according to claim 2, characterized in that, The mass ratio of gold nanoparticles to single-atom nickel is (0.9-6):

1.

4. The gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst according to claim 2, characterized in that, Dual plasmon Au / Ni-W 18 O 49 Heterojunctions possess strong ultraviolet-visible-near-infrared light absorption capabilities and localized surface plasmon resonance effects.

5. A method for preparing a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst as described in any one of claims 1-4, characterized in that, Includes the following steps: Step (1) Synthesize single-atom nickel surface-modified plasmons W by a solution thermal method and an impregnation-thermal reduction process. 18 O 49 Nanowires; Step (2) involves loading gold nanoparticles onto plasmon resonance W using the in-situ reduction of chloroauric acid with ascorbic acid. 18 O 49 A gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst was obtained on nanowires.

6. The method for preparing a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst according to claim 5, characterized in that, Step (1) specifically includes the following steps: (1-1) Tungsten hexachloride was added to anhydrous ethanol solution and stirred until dissolved to obtain a precursor solution; the above precursor solution was added to a stainless steel reactor lined with polytetrafluoroethylene and subjected to solvothermal treatment to obtain plasmon W. 18 O 49 Nanowires; (1-2) Plasmon W 18 O 49 Nanowire powder was ultrasonically dispersed in anhydrous ethanol containing nickel salt to obtain a premix. After continuous stirring for a period of time, the sample was centrifuged and dried, and then thermally reduced in a 10% H2 / Ar mixed gas to obtain a single-atom Ni-modified plasmon W. 18 O 49 Nanowires.

7. The method for preparing a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst according to claim 6, characterized in that, In step (1-1), the concentration of tungsten hexachloride in anhydrous ethanol is 3-5 mg / mL, the temperature of the heat of solution reaction is 160-190 ℃, and the reaction time is 10-18 hours; In steps (1-2), in the premixed solution, Ni in the nickel salt reacts with plasmons W. 18 O 49 The mass ratio of nanowires is 0.1%-0.8%, the thermal reduction temperature is 120-150 ℃, the time is 1-2 hours, and the nickel salt is any one or more of nickel chloride and nickel nitrate.

8. The method for preparing a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst according to claim 5, characterized in that, Step (2) specifically includes the following steps: modifying the prepared single-atom Ni surface with plasmon W 18 O 49 Nanowires were ultrasonically dispersed in anhydrous ethanol, and ascorbic acid reducing agent was added and stirred for 30 minutes. Then, chloroauric acid ethanol solution was added dropwise to the above solution to carry out the reduction reaction. After centrifugation and drying, gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst was obtained.

9. The method for preparing a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst according to claim 8, characterized in that, Plasmon W modified with single-atom Ni surface 18 O 49 The concentration of nanowires in ethanol was 1-3 mg / mL; ascorbic acid reducing agent was added to a concentration of 4-8 mg / mL; Au in the added chloroauric acid reacted with plasmon resonance W. 18 O 49 The mass ratio of nanowires is 0.3%-2.0%; the stirring time for the in-situ reduction of chloroauric acid is 1-3 hours.

10. The application of a gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst as described in any one of claims 1-4, characterized in that, A gold / nickel-tungsten oxide dual plasmon heterojunction photocatalyst is applied to the photocatalytic reduction of CO2.

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