Titanium dioxide loaded noble metal nanoparticle catalyst as well as preparation method and application thereof

Abstract

The invention relates to a titanium dioxide loaded noble metal nanoparticle catalyst and a preparation method and application thereof, the preparation method comprises the following steps: mixing a titanium source, a noble metal source, a phenol source and an aldehyde source, and sequentially carrying out hydrothermal treatment and calcination to obtain the titanium dioxide loaded noble metal nanoparticle catalyst. Only through hydrothermal and calcining treatment, secondary metal loading is not needed, high efficiency is considered, and meanwhile, the preparation cost is reduced. The phenol source and the aldehyde source are adopted, the synergistic effect of the phenol source and the aldehyde source is exerted, the high-dispersion nanoflower structure catalyst is prepared, the surface area is large, and active sites are increased. By utilizing the plasmon effect of noble metal, the electronic structure of titanium dioxide is regulated and controlled and the reduction of carbon dioxide is promoted by loading noble metal elements on high-dispersion titanium dioxide, so that the purpose of efficiently generating a carbon product substance is achieved.

Description

Technical Field

[0001] This invention belongs to the field of carbon dioxide recycling and renewable energy technology, and relates to a catalyst, its preparation method and application, particularly to a titanium dioxide supported noble metal nanoparticle catalyst, its preparation method and application. Background Technology

[0002] As one of the major greenhouse gases, the increased emissions of CO2 are a primary cause of global warming. Therefore, exploring ways to utilize CO2 and convert it into valuable chemicals can not only reduce carbon emissions but also alleviate environmental pressures and contribute to addressing climate change.

[0003] Currently, most technologies for CO2 reduction rely on hydrogen, but the high cost and difficulty in hydrogen production limit the large-scale application of this technology. Therefore, using water as a hydrogen source for CO2 reduction has enormous development potential. The reduction of carbon dioxide with water to produce one-carbon products is an innovative way to utilize carbon resources. Through this process, CO2 can be converted into industrially valuable one-carbon products, thereby achieving the recycling of carbon resources and conserving limited natural resources.

[0004] Methane can serve as a commercially viable alternative to natural gas without requiring significant modifications to existing systems. Therefore, carbon dioxide methanation offers a valuable decarbonization pathway that contributes to carbon neutrality and the carbon cycle, hydrogen utilization, chemical energy storage, and ultimately, achieving net-zero emissions.

[0005] Titanium dioxide (TiO2) is a commonly used material for photocatalytic CO2 reduction due to its abundant content, non-toxicity, low cost, stability, and resistance to photocorrosion. Because of its band gap structure, TiO2 semiconductors can be photoexcited to generate photogenerated electron-hole pairs, thus reducing CO2. By rationally designing the structure and composition of photocatalysts, such as nanostructures, metal doping, and surface modification, the activity and selectivity of photocatalytic CO2 reduction can be significantly improved. For example, thanks to the charge transfer effect generated during photoexcitation, Ag-Au-supported TiO2 catalysts exhibit high catalytic selectivity for the reduction of CO2 to methane under full-wavelength illumination. Currently, constructed TiO2 structures include core-shell structures, nanoparticle structures, and nanosheet structures. However, these structures cannot maximize the utilization of light and heat energy, limiting the activity of CO2 reduction.

[0006] Therefore, considering the absorption of light and the utilization of light energy and heat energy, constructing TiO2 into a highly dispersed nanoflower structure is an effective means. Meanwhile, due to the plasmonic effect of noble metals, the excited photo-generated charges are the key to CO2 reduction, and by loading noble metal elements (Pt, Pd, Ag, Ru, Rh, Au, Os, Ir, etc.) on highly dispersed TiO2, the TiO2 electronic structure is regulated, CO2 reduction is promoted, and the purpose of generating one-carbon products with high efficiency is ultimately achieved. SUMMARY

[0007] To solve the above technical problems, the present application provides a titanium dioxide loaded noble metal nanoparticle catalyst and its preparation method and application. The present application only needs hydrothermal and calcination treatment without secondary metal loading, and both high efficiency and low preparation cost are considered. The present application uses phenolic source and aldehyde source and plays the synergistic effect of the two, and the prepared highly dispersed nanoflower structure catalyst has a high surface area and increases the active sites. Due to the band gap structure of titanium dioxide semiconductor, titanium dioxide can be excited by light to generate photo-generated electron-hole pairs to realize the reduction of carbon dioxide. The noble metal loaded on the surface of titanium dioxide changes the energy band structure of titanium dioxide and provides active sites for carbon dioxide adsorption. At the same time, the plasmonic effect can excite photo-generated charges to improve the light recombination efficiency and further promote the reduction of carbon dioxide.

[0008] To achieve this purpose, the present application adopts the following technical solutions:

[0009] In a first aspect, the present application provides a preparation method of a titanium dioxide loaded noble metal nanoparticle catalyst, which comprises the following steps:

[0010] Mixing a titanium source, a noble metal source, a phenolic source and an aldehyde source, and sequentially performing hydrothermal and calcination to obtain the titanium dioxide loaded noble metal nanoparticle catalyst.

[0011] The present application only needs hydrothermal and calcination treatment without secondary metal loading, and both high efficiency and low preparation cost are considered. By adding phenolic source and aldehyde source during preparation and playing the synergistic effect of the two, the loading of noble metal elements is improved, and a highly dispersed nanoflower structure titanium dioxide loaded noble metal nanoparticle catalyst is prepared.

[0012] Preferably, the titanium source includes any one or a combination of at least two of titanium trichloride, titanium tetrachloride, titanyl sulfate, tetrabutyl titanate, isopropyl titanate or titanium isopropoxide. Typical but non-limiting combinations include a combination of titanium trichloride and titanium tetrachloride, a combination of titanyl sulfate and tetrabutyl titanate, or a combination of tetrabutyl titanate, isopropyl titanate and titanium isopropoxide.

[0013] Preferably, the noble metal source comprises any one or a combination of at least two of a nitrate salt, a chloride salt, or an acidic compound containing a noble metal element, typically but not limitedly a combination of a nitrate salt and a chloride salt, or a combination of a nitrate salt, a chloride salt, and an acidic compound.

[0014] Preferably, the acidic compound containing a noble metal element comprises a crystalline hydrate of an acidic compound.

[0015] Preferably, the noble metal element comprises any one or a combination of at least two of Pt, Pd, Ag, Ru, Rh, Au, Os, or Ir, typically but not limitedly a combination of Pt and Pd, a combination of Ag and Ru, or a combination of Au, Os, and Ir.

[0016] Preferably, the noble metal source comprises any one or a combination of at least two of palladium chloride, chloroauric acid, chloroplatinic acid, or chloroiridic acid, typically but not limitedly a combination of chloroauric acid and palladium chloride, or a combination of chloroauric acid, chloroplatinic acid, and chloroiridic acid.

[0017] Preferably, the phenol source comprises any one or a combination of at least two of cresol, phenol, resorcinol, phloroglucinol, hydroquinone, or catechol, typically but not limitedly a combination of cresol and phenol, a combination of resorcinol and phloroglucinol, or a combination of phloroglucinol, hydroquinone, and catechol.

[0018] Preferably, the aldehyde source comprises any one or a combination of at least two of formaldehyde, acetaldehyde, propionaldehyde, or benzaldehyde, typically but not limitedly a combination of formaldehyde and acetaldehyde, or a combination of acetaldehyde, propionaldehyde, and benzaldehyde.

[0019] Preferably, the mass ratio of the noble metal source and the titanium source is (0.1-1): 100, which can be 0.1: 100, 0.2: 100, 0.4: 100, 0.8: 100, 0.9: 100, or 1: 100, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0020] Preferably, the mass ratio of the titanium source and the phenol source is (1-5): 1, which can be 1: 1, 2: 1, 3: 1, 4: 1, or 5: 1, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0021] Preferably, the mass ratio of the phenol source and the aldehyde source is (0.25-3): 1, which can be 0.25: 1, 0.5: 1, 1: 1, 1.5: 1, 2: 1, 2.5: 1, or 3: 1, but is not limited to the listed values, and other values not listed in the range are also applicable.

[0022] The present application adopts a phenol source and an aldehyde source, and the synergistic effect of both is exerted to prepare a catalyst with a high-dispersed nanoflower structure. The change of the amount of the phenol source and the aldehyde source will cause the change of the sample morphology. When the amount of the aldehyde source is further increased, the morphology tends to form a fiber structure; when the amount of the phenol source is further increased, the morphology tends to form a nanoparticle structure. When the amount of the phenol source and the aldehyde source is controlled at a proper ratio, the prepared catalyst presents a high-dispersed nanoflower structure.

[0023] Preferably, the temperature of the hydrothermal treatment is 80-120℃, for example, can be 80℃, 90℃, 100℃, 110℃ or 120℃, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0024] Preferably, the time of the hydrothermal treatment is 24-72h, for example, can be 24h, 36h, 48h, 60h or 72h, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0025] The temperature and time of the hydrothermal treatment will affect the performance of the catalyst. There is a preferred range of the hydrothermal temperature. Outside the preferred range, the increase or decrease of the hydrothermal temperature will both cause the decrease of the yield of methane and carbon monoxide. There is also a preferred range of the hydrothermal time. Outside the preferred range, the shortening of the hydrothermal time will cause the decrease of the yield of methane and carbon monoxide, while the prolonging of the hydrothermal time will increase the complexity of the process preparation, which is not conducive to reducing the preparation cost.

[0026] Preferably, after the hydrothermal treatment, drying is also needed before calcination.

[0027] Preferably, the temperature of the drying is 60-120℃, for example, can be 60℃, 70℃, 80℃, 90℃, 100℃, 110℃ or 120℃, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0028] Preferably, the time of the drying is 6-48h, for example, can be 6h, 18h, 30h, 42h or 48h, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0029] Preferably, the temperature of the calcination is 600-1000℃, for example, can be 600℃, 700℃, 800℃, 900℃, 950℃ or 1000℃, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0030] Preferably, the time of the calcination is 1-6h, for example, can be 1h, 2h, 3h, 4h, 5h or 6h, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0031] Preferably, the heating rate of the calcination is 1-10℃ / min, for example, it can be 1℃ / min, 3℃ / min, 5℃ / min, 7℃ / min, 9℃ / min or 10℃ / min, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0032] The temperature and time of the calcination affect the performance of the catalyst, there is a preferred range of the calcination temperature, outside the preferred range, the decrease of the calcination temperature will result in the decrease of the yield of methane and carbon monoxide, the increase of the calcination temperature will increase the complexity of the process preparation and the cost of energy consumption; there is also a preferred range of the calcination time, outside the preferred range, the decrease of the calcination time will result in the decrease of the yield of methane and carbon monoxide, the increase of the calcination time will increase the complexity of the process preparation and the cost of energy consumption.

[0033] As a preferred technical solution of the present application, the preparation method comprises the following steps:

[0034] (1) dissolving the titanium source, noble metal source, phenol source and aldehyde source in a solvent, stirring and mixing for 10-30min, and then transferring into a high-pressure reaction kettle;

[0035] (2) placing the reaction kettle into an oven, hydrothermal treatment at 80-120℃ for 24-72h, and then washing with deionized water to obtain gel particles;

[0036] (3) drying the gel particles in an oven at 60-120℃ for 6-48h to obtain dry gel;

[0037] (4) calcining the dry gel at 600-1000℃ for 1-6h to obtain the titanium dioxide supported noble metal nanoparticle catalyst.

[0038] In the second aspect, the present application provides a catalyst prepared by the preparation method of the first aspect, the catalyst comprising a titanium dioxide carrier and a noble metal nanoparticle support.

[0039] Preferably, the noble metal nanoparticle support comprises any one or a combination of at least two of Pt, Pd, Ag, Ru, Rh, Au, Os or Ir, and a typical but non-limiting combination includes a combination of Pt and Pd, a combination of Ag and Ru, or a combination of Au, Os and Ir.

[0040] Preferably, the mass ratio of the noble metal nanoparticle support to the titanium dioxide carrier is (0.1-1):100, for example, it can be 0.1:100, 0.2:100, 0.4:100, 0.8:100, 0.9:100 or 1:100, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0041] Preferably, the structure of the catalyst is a highly dispersed nanoflower structure.

[0042] Due to the band gap structure of titanium dioxide semiconductor, titanium dioxide can be excited by light to generate photo-generated electron-hole pairs to realize the reduction of carbon dioxide. The noble metal loaded on the surface of titanium dioxide changes the energy band structure of titanium dioxide and provides active sites for carbon dioxide adsorption. At the same time, the plasmonic effect can excite photo-generated charges to improve the light recombination efficiency, thereby promoting the reduction of carbon dioxide.

[0043] In a third aspect, the application provides an application of the catalyst as described in the second aspect, which is applied to photocatalytic reduction of carbon dioxide and water to produce one-carbon products.

[0044] Preferably, the mass of the photocatalyst is 2-10 mg, for example, it can be 2 mg, 4 mg, 6 mg, 8 mg or 10 mg, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0045] Preferably, the volume of water for photocatalysis is 0.5-5 mL, for example, it can be 0.5 mL, 1 mL, 2 mL, 3 mL, 4 mL or 5 mL, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0046] Preferably, the visible light irradiation for photocatalysis is 200-1000 nm, for example, it can be 200 nm, 400 nm, 600 nm, 800 nm or 1000 nm, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0047] Preferably, the light intensity for photocatalysis is 500-700 mW / cm 2 , for example, it can be 500 mW / cm 2 , 550 mW / cm 2 , 600 mW / cm 2 , 650 mW / cm 2 or 700 mW / cm 2 , but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0048] Preferably, the light irradiation time for photocatalysis is 60-360 min, for example, it can be 60 min, 180 min, 240 min, 300 min or 360 min, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0049] Compared with the prior art, the application has at least the following beneficial effects:

[0050] (1) The preparation method of the titanium dioxide loaded noble metal nanoparticle catalyst is simple, only water hydrolysis and calcination treatment are needed, secondary metal loading is not needed, the efficient performance is considered, and the preparation cost is reduced; phenolic source and aldehyde source are used, and the synergistic effect of the two is played, high dispersion nanoflower structure is prepared, has high surface area, and the active site is increased; the plasmonic effect of the noble metal is used, the noble metal element is loaded on the high dispersion titanium dioxide, the electronic structure of the titanium dioxide is regulated, the carbon dioxide reduction is promoted, and the purpose of efficiently generating one-carbon product substances is achieved;

[0051] (2) Under the catalytic conversion of the catalyst in the application, carbon dioxide and water can be reacted in a simple and closed container under the action of light, carbon dioxide and water are injected before the reaction, and no other operation is needed during the reaction;

[0052] (3) Under the catalysis of the catalyst in the application, the yield of methane in the reaction product is 0.88 mol·g -1 ·h -1 Above, the yield of carbon monoxide is 9.52 μmol·g -1 ·h -1 Above. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1-1 and Figure 1-2 are scanning electron microscope images of the titanium dioxide loaded noble metal nanoparticle catalyst in Example 1;

[0054] Figure 2-1 and Figure 2-2 are scanning electron microscope images of the titanium dioxide loaded noble metal nanoparticle catalyst in Example 2;

[0055] Figure 3-1 and Figure 3-2 are scanning electron microscope images of the titanium dioxide loaded noble metal nanoparticle catalyst in Example 3;

[0056] Figure 4-1 and Figure 4-2 are scanning electron microscope images of the titanium dioxide loaded noble metal nanoparticle catalyst in Example 4;

[0057] Figure 5-1 and Figure 5-2 are scanning electron microscope images of the titanium dioxide loaded noble metal nanoparticle catalyst in Example 5;

[0058] Figure 6-1 and Figure 6-2 are scanning electron microscope images of the titanium dioxide loaded noble metal nanoparticle catalyst in Comparative Example 1;

[0059] Figure 7-1 and Figure 7-2is a scanning electron microscope image of the titanium dioxide supported noble metal nanoparticle catalyst in Comparative Example 2;

[0060] Figure 8-1 and Figure 8-2 is a scanning electron microscope image of the titanium dioxide supported noble metal nanoparticle catalyst in Comparative Example 3;

[0061] Figure 9 is an XRD pattern of the titanium dioxide supported noble metal nanoparticle catalyst in Examples 1-3 and Comparative Example 3;

[0062] Figure 10 is an XRD pattern of the titanium dioxide supported noble metal nanoparticle catalyst in Examples 4-5 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0063] The technical solutions of the present application are further illustrated below by specific embodiments in conjunction with the accompanying drawings. However, the following examples are only simple examples of the present application and do not represent or limit the protection scope of the present application, and the protection scope of the present application is subject to the claims.

[0064] Example 1

[0065] The present embodiment provides a preparation method of a titanium dioxide supported noble metal nanoparticle catalyst, which comprises the following steps:

[0066] (1) 3.1 g of TiCl3, 17.7 mg of PdCl2, and 2.6 g of resorcinol were added to a beaker containing 20 mL of deionized water, and then 3.6 g of formaldehyde was added. After stirring for 20 min, the precursor solution was transferred to a stainless steel high-pressure reaction kettle;

[0067] (2) The reaction kettle was placed in an oven and hydrothermally treated at 90°C for 72 h. After washing with deionized water for 3 times, gel particles were obtained;

[0068] (3) The gel particles were dried in an oven at 80°C for 12 h to obtain a dry gel;

[0069] (4) The dry gel was transferred to a tube furnace and heated to 700°C at a heating rate of 5°C / min. After calcination for 2 h, the titanium dioxide supported noble metal nanoparticle catalyst was obtained.

[0070] Figure 1-1 and Figure 1-2 is a scanning electron microscope image of the titanium dioxide supported noble metal nanoparticle catalyst in Example 1, from which it can be seen that the sample with TiCl3 as the titanium source is generally in the form of dispersed nanoparticles, and under a high magnification image, it presents a highly dispersed nanoflower structure.

[0071] Example 2

[0072] This embodiment provides a method for preparing a titanium dioxide-supported noble metal nanoparticle catalyst, the preparation method comprising the following steps:

[0073] (1) Add 3.4g tetrabutyl titanate, 3.4mg PdCl2 and 3.4g phloroglucinol to a beaker containing 100mL deionized water, then add 1.13g propionaldehyde, stir for 30min, and then transfer the precursor solution to a stainless steel high-pressure reactor.

[0074] (2) Place the reactor in an oven and heat it at 80°C for 72 hours. Then wash it twice with deionized water to obtain gel particles.

[0075] (3) Dry the gel particles in an oven at 120°C for 6 hours to obtain a dry gel;

[0076] (4) The dry gel was transferred to a tube furnace and heated to 1000°C at a heating rate of 10°C / min. After calcination for 1 hour, the titanium dioxide supported noble metal nanoparticle catalyst was obtained.

[0077] Figure 2-1 and Figure 2-2 This is a scanning electron microscope image of the titanium dioxide-supported noble metal nanoparticle catalyst in Example 2. As can be seen from the image, the sample with tetrabutyl titanate as the titanium source is in the form of dispersed nanoparticles.

[0078] Example 3

[0079] This embodiment provides a method for preparing a titanium dioxide-supported noble metal nanoparticle catalyst, the preparation method comprising the following steps:

[0080] (1) Add 6.2g TiCl3, 62mg HAuCl4·4H2O and 1.24g cresol to a beaker containing 150mL deionized water, then add 4.96g benzaldehyde, stir for 40min, and then transfer the precursor solution to a stainless steel high-pressure reactor.

[0081] (2) The reaction vessel was placed in an oven and heated at 120°C for 24 hours. After that, it was washed four times with deionized water to obtain gel particles.

[0082] (3) The gel particles were dried in an oven at 60°C for 48 hours to obtain a dry gel;

[0083] (4) The dry gel was transferred to a tube furnace and heated to 600°C at a heating rate of 1°C / min. After calcination for 6 hours, the titanium dioxide supported noble metal nanoparticle catalyst was obtained.

[0084] Figure 3-1 and Figure 3-2This is a scanning electron microscope (SEM) image of the titanium dioxide-supported noble metal nanoparticle catalyst in Example 3. As can be seen from the image, the sample with TiCl3 as the titanium source generally exhibits a dispersed nanoparticle structure, and the high-magnification image shows a highly dispersed nanoflower structure.

[0085] Example 4

[0086] The only difference between this embodiment and Example 1 is that, except for step (1) which uses 0.72g of resorcinol and 3.6g of formaldehyde, i.e., the mass ratio of phenol source to aldehyde source is 0.2:1, everything else is the same as in Example 1.

[0087] Figure 4-1 and Figure 4-2 This is a scanning electron microscope image of the titanium dioxide-supported noble metal nanoparticle catalyst in Example 4. As can be seen from the image, when the aldehyde source is in excess, the sample exhibits a smooth nanofiber-nanoparticle state.

[0088] Example 5

[0089] The only difference between this embodiment and Example 1 is that, except for step (1) which uses 2.6g of resorcinol and 0.65g of formaldehyde, i.e., the mass ratio of phenol source to aldehyde source is 4:1, everything else is the same as in Example 1.

[0090] Figure 5-1 and Figure 5-2 This is a scanning electron microscope image of the titanium dioxide-supported noble metal nanoparticle catalyst in Example 5. As can be seen from the image, when the phenol source is in excess, the sample exhibits a fine nanoparticle aggregate state.

[0091] Example 6

[0092] The only difference between this embodiment and embodiment 1 is that, except that the temperature of the hydrothermal treatment in step (2) is 70°C, everything else is the same as in embodiment 1.

[0093] Example 7

[0094] The only difference between this embodiment and embodiment 1 is that, except that the temperature of the hydrothermal treatment in step (2) is 130°C, everything else is the same as in embodiment 1.

[0095] Example 8

[0096] The only difference between this embodiment and embodiment 1 is that, except that the hydrothermal time in step (2) is 22 hours, everything else is the same as in embodiment 1.

[0097] Example 9

[0098] The only difference between this embodiment and embodiment 1 is that, except for the hydrothermal time in step (2) which is 75 hours, everything else is the same as in embodiment 1.

[0099] Example 10

[0100] The only difference between this embodiment and embodiment 1 is that, except that the calcination temperature in step (4) is 550°C, everything else is the same as in embodiment 1.

[0101] Example 11

[0102] The only difference between this embodiment and embodiment 1 is that, except that the calcination temperature in step (4) is 1050°C, everything else is the same as in embodiment 1.

[0103] Example 12

[0104] The only difference between this embodiment and embodiment 1 is that, except that the calcination time in step (4) is 0.5 h, everything else is the same as in embodiment 1.

[0105] Example 13

[0106] The only difference between this embodiment and embodiment 1 is that, except that the calcination time in step (4) is 6.5 hours, everything else is the same as in embodiment 1.

[0107] Example 14

[0108] The only difference between this embodiment and embodiment 1 is that, except for step (3) not being performed, everything else is the same as in embodiment 1.

[0109] Comparative Example 1

[0110] The only difference between this comparative example and Example 1 is that, except that step (1) uses only 2.6g of resorcinol and no formaldehyde is added, everything else is the same as in Example 1.

[0111] Figure 6-1 and Figure 6-2 This is a scanning electron microscope image of the titanium dioxide-supported noble metal nanoparticle catalyst in Comparative Example 1. As can be seen from the image, the sample is highly aggregated when no aldehyde source is added.

[0112] Comparative Example 2

[0113] The only difference between this comparative example and Example 1 is that, except that step (1) uses only 3.6g of formaldehyde and does not add resorcinol, everything else is the same as in Example 1.

[0114] Figure 7-1 and Figure 7-2 This is a scanning electron microscope image of the titanium dioxide-supported noble metal nanoparticle catalyst in Comparative Example 2. As can be seen from the image, when no phenol source is added, the sample is in the form of dispersed smooth nanoparticles.

[0115] Figure 10The figures show the XRD patterns of titanium dioxide-supported noble metal nanoparticle catalysts in Examples 4-5 and Comparative Examples 1-2. As can be seen from the figures, without the addition of formaldehyde or resorcinol, the XRD patterns of both failed to show the PdO peak shape, indicating that the lack of aldehyde or phenol will lead to poor loading of Pd element.

[0116] Comparative Example 3

[0117] The only difference between this comparative example and Example 1 is that, except that PdCl2 is not added in step (1), everything else is the same as in Example 1.

[0118] Figure 8-1 and Figure 8-2 The image shows a scanning electron microscope (SEM) image of the titanium dioxide-supported noble metal nanoparticle catalyst in Comparative Example 3. As can be seen from the image, when no noble metal source is added, the morphology of the catalyst is not significantly affected, and the prepared catalyst is in the form of dispersed nanoparticles.

[0119] Figure 9 The figures show the XRD patterns of the titanium dioxide-supported noble metal nanoparticle catalysts in Examples 1-3 and Comparative Example 3. As can be seen from the figures, the titanium dioxide prepared by this invention has a rutile structure, and the corresponding noble metals are successfully loaded.

[0120] Test methods

[0121] Weigh 2 mg of the catalysts prepared in Examples 1-14 and Comparative Examples 1-3 respectively, and irradiate them with 2.5 mL of water under 800 nm visible light with a light intensity of 580 mW / cm². 2 The photocatalytic reaction was carried out under a high-purity CO2 gas environment with an illumination time of 120 min, and the yields of methane and carbon monoxide were recorded in Table 1.

[0122] Table 1

[0123]

[0124]

[0125] The test results show that:

[0126] (1) As can be seen from Examples 1-14 and Comparative Examples 1-3, the present invention only requires hydrothermal and calcination treatment, without secondary metal loading, which reduces the preparation cost while maintaining high efficiency; by using phenol and aldehyde sources and leveraging their synergistic effect, a highly dispersed nano-flower-like structure is prepared, which has a high surface area and increases the number of active sites; by utilizing the plasmon effect of noble metals, noble metal elements are loaded on highly dispersed titanium dioxide to regulate the electronic structure of titanium dioxide, promote carbon dioxide reduction, and achieve the goal of generating one-carbon product-like substances with high efficiency.

[0127] (2) As can be seen from Examples 1, 4-5 and Comparative Examples 1-2, the present invention uses phenolic source and aldehyde source and gives full play to their synergistic effect to prepare a catalyst with highly dispersed nano-flower structure; and by further controlling the mass ratio of phenolic source and aldehyde source, the dispersibility and catalytic activity of the catalyst are further improved, and the yields of methane and carbon monoxide are further improved.

[0128] (3) As can be seen from Examples 1 and 6-9, by further controlling the temperature and time of the hydrothermal reaction, the catalyst prepared by the present invention has a further improved yield of methane and carbon monoxide.

[0129] (4) As can be seen from Examples 1 and 10-13, by further controlling the calcination temperature and time, the catalyst prepared by the present invention has a further improved yield of methane and carbon monoxide.

[0130] (5) As can be seen from Examples 1 and 14, the catalyst prepared by the present invention by introducing a drying step in the hydrothermal and calcination process further improves the yield of methane and carbon monoxide.

[0131] (6) As can be seen from Example 1 and Comparative Example 3, the present invention changes the band structure of titanium dioxide by loading noble metals on the surface of titanium dioxide, and also provides active sites for carbon dioxide adsorption. At the same time, the plasmon effect can excite photogenerated charges, improve photorecombination efficiency, and thus promote carbon dioxide reduction.

[0132] In summary, this invention utilizes only hydrothermal and calcination treatments, eliminating the need for secondary metal loading, thus achieving both high efficiency and reduced preparation costs. By employing phenol and aldehyde sources and leveraging their synergistic effect, a highly dispersed nanoflower-like structure with a large surface area is prepared, increasing the number of active sites. Utilizing the plasmon resonance effect of noble metals, by loading noble metal elements onto highly dispersed titanium dioxide, the electronic structure of titanium dioxide is modulated, promoting carbon dioxide reduction and achieving the goal of efficiently generating one-carbon products.

[0133] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a titanium dioxide-supported noble metal nanoparticle catalyst, characterized by, The preparation method comprises the following steps: Mixing a titanium source, a noble metal source, a phenol source and an aldehyde source, and sequentially performing hydrothermal treatment and calcination to obtain the titanium dioxide supported noble metal nanoparticle catalyst.

2. The production method according to claim 1, characterized by, The titanium source comprises any one or a combination of at least two of titanium trichloride, titanium tetrachloride, titanyl sulfate, tetrabutyl titanate, isopropyl titanate or titanium isopropoxide; Preferably, the noble metal source comprises any one or a combination of at least two of a nitrate, a chloride or an acidic compound containing a noble metal element; Preferably, the noble metal element comprises any one or a combination of at least two of Pt, Pd, Ag, Ru, Rh, Au, Os or Ir.

3. The production method according to claim 1 or 2, characterized by, The phenol source comprises any one or a combination of at least two of methylphenol, phenol, m-dihydroxybenzene, p-dihydroxybenzene or o-dihydroxybenzene; Preferably, the aldehyde source comprises any one or a combination of at least two of formaldehyde, acetaldehyde, propyl aldehyde or benzaldehyde.

4. The production method according to any one of claims 1 to 3, characterized by, The mass ratio of the noble metal source and the titanium source is (0.1-1):100; Preferably, the mass ratio of the titanium source and the phenol source is (1-5):1; Preferably, the mass ratio of the phenol source and the aldehyde source is (0.25-3):

1.

5. The method of any one of claims 1-4, wherein, The temperature of the hydrothermal treatment is 80-120℃; Preferably, the time of the hydrothermal treatment is 24-72h; Preferably, after the hydrothermal treatment and before the calcination, drying is further required; Preferably, the temperature of the drying is 60-120℃; Preferably, the time of the drying is 6-48h.

6. The method of any one of claims 1-5, wherein, The temperature of the calcination is 600-1000℃; Preferably, the time of the calcination is 1-6h; Preferably, the heating rate of the calcination is 1-10℃ / min.

7. The preparation method according to claim 1, characterized in that, The preparation method comprises the following steps: (1) Dissolving a titanium source, a noble metal source, a phenol source and an aldehyde source in a solvent, stirring and mixing for 10-30min, and then transferring into a high-pressure reaction kettle; (2) Placing the reaction kettle into an oven, performing hydrothermal treatment at 80-120℃ for 24-72h, and then washing with deionized water for 2-4 times to obtain gel particles; (3) Drying the gel particles at 60-120℃ for 6-48h to obtain dry gel; (4) Calcining the dry gel at 600-1000℃ for 1-6h to obtain the titanium dioxide supported noble metal nanoparticle catalyst.

8. A catalyst obtainable by the process according to any one of claims 1 to 7, characterized in that The catalyst comprises a titanium dioxide carrier and a noble metal nanoparticle support.

9. The catalyst of claim 8, wherein The noble metal nanoparticle support comprises any one or a combination of at least two of Pt, Pd, Ag, Ru, Rh, Au, Os or Ir; Preferably, the structure of the catalyst is a highly dispersed nanoflower structure.

10. Use of a catalyst as claimed in claim 8 or 9, characterised in that, The catalyst is applied to photocatalytic reduction of carbon dioxide and water to produce one-carbon products.

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