A ruthenium-loaded black titanium dioxide composite material, its preparation method and application

Abstract

The invention belongs to the field of carbon neutralization technology, and discloses a black titanium dioxide composite material loaded with ruthenium nanoparticles, a preparation method thereof and an application thereof. The catalyst modulates the electronic structure of titanium dioxide through sodium borohydride modification to form a unique Ti-H···Ti-OH frustrated Lewis acid-base pair, realizing the photothermal catalytic reduction of carbon dioxide to carbon monoxide at a temperature above 200 °C, with a selectivity exceeding 99%, and reversing the methane selectivity of the unmodified ruthenium nanoparticle-loaded white titanium dioxide. The average particle size of the ruthenium nanoparticles loaded on the catalyst surface is 2-5 nanometers, and the loading amount is 0.5%-5%. The catalyst of the invention exhibits excellent synergistic effects in photothermal catalysis, providing an efficient solution for the high-value utilization of carbon dioxide.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide reduction, and in particular relates to a black titanium dioxide composite material loaded with ruthenium nanoparticles, a preparation method thereof, and an application thereof. Background Art

[0002] Carbon dioxide is an important greenhouse gas and also a potential chemical and energy material. As an important intermediate in the earth's carbon cycle, carbon dioxide is not only the bridge between inorganic-organic carbon cycles but also an essential raw material for plant photosynthesis. By reducing carbon dioxide, various high-value chemicals such as methane, methanol, and carbon monoxide can be prepared. Among them, carbon monoxide is not only an important component of syngas but also the basic raw material for the preparation of higher alkanes and other chemical products, and is widely used in industrial processes such as Fischer-Tropsch synthesis.

[0003] Currently, industrial technologies for reducing carbon dioxide to high-value products such as methane or carbon monoxide mainly rely on thermal catalytic reactions. By using Fe-based, Co-based, Pt-based, or Ru-based catalysts under high temperature and high pressure conditions, carbon dioxide can be effectively converted into target products. However, the thermal catalytic process requires a large amount of fossil energy for power supply, which is not only difficult to achieve full-process carbon neutrality but also brings additional carbon dioxide emissions due to the combustion of fossil energy. Therefore, developing carbon dioxide reduction technologies driven by clean energy is of great significance for alleviating climate change and energy crises.

[0004] Solar energy, as a clean and renewable energy source, has received extensive attention due to its abundance and sustainability. Although solar thermal power generation and water heater technologies are relatively mature, directly converting solar energy into chemical energy to drive reactions remains a technical challenge. As a comprehensive technology that combines the photoelectric effect and the thermal energy effect, the photothermal catalytic technology can utilize the full-spectrum sunlight, generate photoinduced carriers through high-frequency photons, and heat the catalyst surface with low-frequency photons to achieve a synergistic catalytic effect. However, in the prior art, how to achieve selective reduction of carbon dioxide molecules through photothermal catalysis, especially to regulate the selectivity between products such as methane and carbon monoxide, remains an unsolved core scientific problem.

[0005] Ruthenium-based catalysts are widely regarded as efficient catalysts for the carbon dioxide reduction reaction, but their regulation of product selectivity highly depends on the properties of the support. Ruthenium catalysts on traditional unmodified supports usually tend to produce methane. For the need to prepare carbon monoxide, precise regulation of the electronic structure and surface active sites of the support is required. If the product selectivity of ruthenium-based catalysts can be reversed through support modification, so as to efficiently reduce carbon dioxide to carbon monoxide under atmospheric pressure, it will greatly improve the application potential of photothermal catalytic technology in the field of carbon neutrality and provide a new solution for green chemical synthesis. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a black titanium dioxide composite material loaded with ruthenium nanoparticles, and its preparation method and application. The present invention provides a catalyst that can efficiently focus sunlight, efficiently activate carbon dioxide, and significantly improve the selectivity of carbon dioxide reduction products. The present invention uses sunlight as the only energy input, and uses a xenon lamp light source to simulate sunlight during the laboratory testing phase. The catalyst in the present invention can efficiently utilize full-band sunlight, including ultraviolet, visible light and infrared bands, and drive the reduction reaction of carbon dioxide through the photothermal synergistic effect.

[0007] The first object of the present invention is to provide a black titanium dioxide composite material loaded with ruthenium nanoparticles, characterized in that black titanium dioxide is used as a carrier, and ruthenium nanoparticles are loaded on the surface of the carrier, and the surface of the carrier contains a Ti-HOV···Ti-OH hindered Lewis acid-base pair.

[0008] In some embodiments of the present invention, the loading amount of the ruthenium nanoparticles is 0.5 wt%-5 wt%;

[0009] The average particle size of the ruthenium nanoparticles is 2-5 nanometers.

[0010] A second object of the present invention is to provide a method for preparing a black titanium dioxide composite material loaded with ruthenium nanoparticles, comprising the following steps:

[0011] P25 titanium dioxide and a reducing agent are mixed, the resulting mixture is light-milled (for 20 to 40 minutes), and then heated and calcined to obtain a black powder;

[0012] The obtained black powder is mixed with water for reaction, the solid-liquid separation is performed to obtain the solid phase, and the obtained solid phase is dried under light in an inert atmosphere to obtain modified titanium dioxide BTO;

[0013] Dispersing modified titanium dioxide (BTO) in a ruthenium-containing precursor solution to obtain a suspension; removing the solvent from the suspension to obtain a precursor;

[0014] The precursor is photoreduced in a reducing atmosphere to obtain the black titanium dioxide composite material loaded with ruthenium nanoparticles.

[0015] In some embodiments of the present invention, the mass ratio of the p25 titanium dioxide to the reducing agent is 1:(2-4);

[0016] The reducing agent is selected from one or more of sodium borohydride, potassium borohydride, lithium aluminum hydride, sodium hydride and lithium hydride;

[0017] The heating and calcining temperature is 200-500° C. and the time is 10-120 minutes.

[0018] In some embodiments of the present invention, during the mixing and reaction of the black powder with water, the black powder reacts violently and releases heat, while a large amount of gas is released. After the gas release stops, the product is further centrifugally washed with distilled water at least three times, and finally washed with ethanol at least three times.

[0019] In some embodiments of the present invention, the ruthenium-containing precursor in the ruthenium-containing precursor solution is selected from one or more of ruthenium dodecacarbonyl, ruthenium chloride, ruthenium acetylacetonate, and ruthenium acetate;

[0020] The solvent of the ruthenium-containing precursor solution is selected from one or more of methanol, ethanol, tetrahydrofuran, acetone, and cyclohexane;

[0021] The ruthenium concentration in the ruthenium-containing precursor solution is 100 - 2000 ppm;

[0022] The non-reactive gas in the inert atmosphere is selected from one or more of nitrogen, argon, helium, and neon;

[0023] The light source in the light drying is infrared light, and the light irradiation time is 1 - 3 hours.

[0024] In some embodiments of the present invention, the mass ratio of ruthenium loaded in the modified titanium dioxide BTO is 0.1 - 5 wt%.

[0025] In some embodiments of the present invention, the reducing gas in the reducing atmosphere includes hydrogen and a non-reactive gas, and the non-reactive gas is selected from one or more of nitrogen, helium, argon, and neon;

[0026] The volume ratio of hydrogen to the non-reactive gas is (3:1) - (1:3);

[0027] The total gas flow rate in the reducing atmosphere is 50 - 100 mL / min;

[0028] The temperature of the light reduction is 200 - 280 °C, and the time is 4 - 8 h.

[0029] In the present invention, the method for removing the solvent from the suspension uses a rotary evaporator, and the solvent is removed by vacuum distillation in a water bath at 40 - 60 °C.

[0030] The third object of the present invention lies in the application of the ruthenium-loaded nanoparticle black titanium dioxide composite material in the photocatalytic reduction of carbon dioxide to carbon monoxide.

[0031] In some embodiments of the present invention, a mixed gas of carbon dioxide and hydrogen is introduced in the photocatalytic reaction;

[0032] Among them, the volume ratio of carbon dioxide to hydrogen is (4:1) - (1:4);

[0033] In the photothermal catalytic reaction, the reaction temperature is greater than or equal to 200 °C, and further preferably 200-400 °C. The temperature control is tested by a thermistor probe in direct contact with the catalyst surface. The gas flow rate is controlled by an electronic flowmeter. The reactor carrying the catalyst is made of quartz.

[0034] In some embodiments of the present invention, before the photocatalytic reaction, the black titanium dioxide composite material loaded with ruthenium nanoparticles needs to be activated. The activation conditions are: under the conditions of 180-300 °C, irradiated with light for 6-8 hours in a reducing atmosphere.

[0035] The core innovation of the present invention lies in modifying and regulating the electronic structure of the titanium dioxide (BTO) support by sodium borohydride to construct a unique frustrated Lewis pair (Ti-HOV···Ti-OH), which significantly reverses the selectivity of the ruthenium-loaded catalyst, switching the main product of carbon dioxide reduction from methane to carbon monoxide, with a selectivity exceeding 99%. The realization of this reversed selectivity not only overcomes the problem of traditional catalysts in controlling product distribution, but also greatly improves the performance stability and industrial applicability of the catalyst in photothermal carbon dioxide reduction.

[0036] The catalyst in the present invention can achieve efficient light absorption and photothermal conversion. When only using a xenon lamp as the energy input, the surface temperature of the catalyst can be freely adjusted to 200-550 °C to meet different reaction requirements. The photothermal synergistic catalytic characteristics of the catalyst in the present invention can efficiently and stably reduce carbon dioxide to carbon monoxide under normal pressure, while significantly reducing the problems of high energy consumption and high cost of traditional thermal catalytic technologies, and the deficiency of existing photocatalytic technologies in carbon dioxide activation ability.

[0037] In summary, through the catalyst design with reversed selectivity, the present invention significantly improves the controllability of the products in the carbon dioxide reduction reaction, provides a new idea for the carbon dioxide reduction technology driven by solar energy, and has important environmental and energy significance.

[0038] The above technical solutions of the present invention have the following advantages compared with the prior art:

[0039] 1. Environmentally friendly driving method. Using solar energy for photocatalytic reduction of carbon dioxide has the advantages of environmental friendliness and low cost. Since the catalyst in the present invention can fully utilize the light energy of each band of sunlight, and the light absorption ability of the carrier black titanium dioxide is improved by modification with sodium borohydride, compared with white titanium dioxide, black titanium dioxide has stronger absorption ability in the visible light and near-infrared light regions. This modification enables the catalyst of the present invention to control the reaction temperature on the catalyst surface to reach 200 - 400 °C by regulating the light intensity when only using focused sunlight, thereby achieving efficient solar energy utilization and photothermal conversion. Its performance of catalytic reduction of carbon dioxide at atmospheric pressure to carbon monoxide under concentrated solar energy can reach more than 10 mmol CO / (g catalyst·h), greatly improving the efficiency of photocatalytic reduction.

[0040] 2. Unique active site structure. The modification with sodium borohydride forms unique surface hydroxyl Ti-OH and hydrogen-carrying oxygen vacancies Ti-HOV in the substrate material BTO. Among them, the hydrogen in Ti-HOV carries partial negative charge and is a Lewis base; the hydrogen in Ti-OH carries partial positive charge and is a Lewis acid, Ti-HOV and Ti-OH. The two are not connected by chemical bonds and present a discrete posture in space, constituting a frustrated Lewis acid-base pair Ti-HOV···Ti-OH. This active site can directly activate an oxygen atom in gaseous carbon dioxide and generate water and carbon monoxide. Under a hydrogenation atmosphere, ruthenium nanoparticles loaded on the surface of BTO can efficiently activate hydrogen to generate hydrogen spillover, and the hydrogen spillover further hydrogenates the surface of BTO to supplement the consumed Ti-HOV···Ti-OH.

[0041] 3. Achieved selective reversal of ruthenium-based catalysts. The present invention reverses the selectivity of traditional ruthenium-based catalysts. Traditional ruthenium-based catalysts usually tend to selectively produce methane in the carbon dioxide reduction reaction, while the present invention shows extremely strong carbon monoxide selectivity during the reaction through the optimization of the catalyst structure. Specifically, the frustrated Lewis acid-base pair Ti-HOV···Ti-OH on the highly active carrier BTO quickly converts carbon dioxide into carbon monoxide, inhibits methanation on ruthenium particles, and instead converts ruthenium nanoparticles into hydrogen spillover centers to supplement the consumed Ti-HOV···Ti-OH. The synergistic effect of the loaded ruthenium nanoparticles and black titanium dioxide enables the catalyst to have excellent activity and carbon monoxide selectivity in the carbon dioxide reduction reaction.

[0042] 4. In-situ active site construction technology enhances the stability of the catalyst. Since the frustrated Lewis pair active sites in the above catalyst can be rapidly regenerated under reaction conditions, the catalyst of the present invention has high catalytic activity and stability. Hydrogen acts as a reactant and also as one of the raw materials for active site construction. The hydrogen spillover effect generated by the supported ruthenium nanoparticles further hydrogenates the surface of black titanium dioxide, which is the key to the construction of reaction sites. This process is sustainable at high temperatures. The continuous introduction of hydrogen enables these sites to be continuously regenerated and recycled under the reaction atmosphere, thereby stabilizing the activity of the catalyst.

[0043] In summary, the present invention provides a catalyst that can efficiently focus solar energy to activate and hydrogenate carbon dioxide to produce carbon monoxide. Through the modification of the black titanium dioxide support and the combined action of frustrated Lewis pairs, the catalyst of the present invention can effectively utilize the full-spectrum light energy in the wavelength range of 200 nm to 2500 nm in sunlight, showing extremely high photothermal conversion ability and carbon dioxide reduction catalytic activity. Compared with traditional ruthenium-based catalysts, the catalyst of the present invention successfully reverses the reaction selectivity, effectively improves the selectivity of carbon monoxide, and reduces the generation of by-products. The above processes are all powered by concentrated sunlight, solving the problem of additional carbon emissions brought by fossil energy and having high commercial prospects. Brief Description of the Drawings

[0044] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to specific embodiments of the present invention in combination with the drawings, wherein,

[0045] Figure 1 is the X-ray diffraction pattern of the Ru / BTO catalyst obtained in Example 1 of the present invention;

[0046] Figure 2 is the high-resolution transmission electron microscope image of the Ru / BTO catalyst obtained in Example 1 of the present invention;

[0047] Figure 3 is the scanning transmission electron microscope photograph and energy-dispersive X-ray spectroscopy of the Ru / BTO catalyst obtained in Example 1 of the present invention;

[0048] Figure 4 is the activity of the Ru / BTO catalyst obtained in Example 1 of the present invention;

[0049] Figure 5 is the activity and selectivity of the Ru / BTO catalyst and the Ru / TiO2 catalyst obtained in Example 1 of the present invention;

[0050] Figure 6 is the solid nuclear magnetic spectrum of the Ru / BTO catalyst obtained in Example 1 of the present invention;

[0051] Figure 7 This is the electron paramagnetic resonance spectrum of the Ru / BTO catalyst obtained in Example 1 of the present invention. Detailed implementation mode

[0052] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the exemplified embodiments are not intended to limit the present invention.

[0053] Example 1

[0054] This example provides the synthesis of the Ru / BTO catalyst:

[0055] 1. Modify p25 titanium dioxide by the sodium borohydride calcination method, and the specific steps are as follows:

[0056] (1) Uniformly mix 1 g of p25 titanium dioxide and 2 g of sodium borohydride in an agate mortar to obtain a mixture;

[0057] (2) Uniformly grind the mixture obtained in step (1) under the irradiation of an infrared lamp for 20 minutes, and then calcine it in a muffle furnace at a calcination temperature of 300 °C for 60 minutes to obtain a black powder;

[0058] (3) Place the black powder obtained in step (2) in a beaker, add 10 ml of distilled water to it. At this time, the black powder reacts violently and releases heat, and a large amount of gas is also released. After the gas release stops, the product is further centrifugally washed three times with distilled water and finally washed three times with ethanol. The obtained product is dried under the irradiation of an infrared lamp for 1 hour in an inert atmosphere of argon to obtain BTO; note here: the product must be completely cooled before being transferred out of the inert atmosphere, otherwise the highly active BTO may spontaneously combust when it encounters air.

[0059] 2. Modify BTO by the impregnation-photoreduction method, and the specific steps are as follows:

[0060] (1) Disperse 1 g of the obtained BTO in a solution containing a ruthenium precursor, and use dodecacarbonylruthenium as the ruthenium precursor; the solvent is tetrahydrofuran. The actual ruthenium content in the solution is configured according to the required ruthenium mass ratio (1%). The suspension formed by BTO and the precursor solution is ultrasonically treated for 40 minutes and then uniformly mixed, and then transferred to a magnetic stirrer and stirred for 4 hours so that the ruthenium precursor is fully adsorbed on the carrier BTO;

[0061] (2) The suspension is then transferred to a rotary evaporator and the solvent is removed by vacuum distillation in a 60 °C water bath to obtain a catalyst precursor;

[0062] (3) The catalyst precursor was placed in a quartz reactor and subjected to light reduction in a reducing atmosphere. The reducing atmosphere was a hydrogen-argon mixture (the volume ratio of hydrogen to argon was 1:3, and the total flow rate was 100 mL / min). The reduction temperature was 200 degrees Celsius and the reduction time was 8 hours. After reduction, a Ru / BTO catalyst with a loading of 1 wt% was obtained. In the reduction process, a xenon lamp was the only light source. The temperature control was tested by directly contacting the catalyst surface with a thermistor probe. The gas flow was controlled by an electronic flow meter. The reactor supporting the catalyst was made of quartz. The obtained Ru / BTO catalyst was structurally characterized. The results are shown in Figure 2. Figure 1 、 Figure 2 and Figure 3 .

[0063] Example 2

[0064] This example provides the synthesis of Ru / BTO catalyst:

[0065] 1. Modify P25 titanium dioxide using lithium aluminum hydride calcination method. The specific steps are as follows:

[0066] (1) 1 g of p25 titanium dioxide and 4 g of lithium aluminum hydride were uniformly mixed in an agate mortar to obtain a mixture;

[0067] (2) the mixture obtained in step (1) was uniformly ground under irradiation of an infrared lamp for 30 minutes, and then calcined in a muffle furnace at a temperature of 240 degrees Celsius for 30 minutes to obtain a black powder;

[0068] (3) The black powder obtained in step (2) was placed in a beaker and 10 ml of distilled water was added. The black powder then reacted vigorously and released heat, while also releasing a large amount of gas. After the gas release ceased, the product was further washed three times by centrifugation with distilled water and finally washed three times with ethanol. The resulting product was then dried under an inert atmosphere of argon using an infrared lamp for 1 hour to obtain BTO. Note: The product must be completely cooled before being removed from the inert atmosphere; otherwise, the highly reactive BTO may spontaneously ignite upon contact with air.

[0069] 2. Use the impregnation-photoreduction method to load modify BTO. The specific steps are as follows:

[0070] (1) 1 gram of the obtained BTO was dispersed in a solution containing a ruthenium precursor, using ruthenium chloride as the ruthenium precursor; the solvent used was ethanol. The actual ruthenium content in the solution was configured according to the required ruthenium mass ratio (2%). The suspension formed by BTO and the precursor solution was uniformly mixed after ultrasonication for 40 minutes, and then transferred to a magnetic stirrer and stirred for 4 hours to allow the ruthenium precursor to be fully adsorbed on the carrier BTO;

[0071] (2) The suspension was then transferred to a rotary evaporator and the solvent was removed by vacuum distillation in a 70 °C water bath to obtain a catalyst precursor;

[0072] (3) The catalyst precursor was placed in a quartz reactor and subjected to photoreduction in a reducing atmosphere. The reducing atmosphere was a hydrogen-argon mixture (ratio 3:1, total flow rate 100 mL / min), the reduction temperature was 250 °C, the reduction time was 8 h, and a Ru / BTO catalyst with a loading of 2 wt% was obtained after reduction. Among them, during the reduction process, the xenon lamp was the only light source, the temperature was controlled by directly contacting the surface of the catalyst with a thermistor probe, the gas flow rate was controlled by an electronic flowmeter, and the reactor for carrying the catalyst was made of quartz.

[0073] Example 3

[0074] This example provides the synthesis of a Ru / BTO catalyst:

[0075] 1. The p25 titanium dioxide was modified by the sodium hydride calcination method, and the specific steps were as follows:

[0076] (1) 1 g of p25 titanium dioxide and 1 g of sodium hydride were uniformly mixed in an agate mortar to obtain a mixture; note here: sodium hydride is more chemically active than sodium borohydride and lithium aluminum hydride in Examples 1 and 2, and operations should be carried out in a dry environment to ensure safety;

[0077] (2) The mixture obtained in step (1) was uniformly ground under the irradiation of an infrared lamp for 10 minutes, and then calcined in a muffle furnace at a calcination temperature of 200 °C for 10 minutes to obtain a black powder;

[0078] (3) The black powder obtained in step (2) was placed in a beaker, and 40 mL of an aqueous solution of 50% ethanol was added thereto. At this time, the black powder reacted violently and released heat, and a large amount of gas was also released. After the gas release stopped, the product was further centrifuged and washed three times with distilled water, and finally washed three times with ethanol. The obtained product was dried by irradiating with an infrared lamp for 1 hour under an inert atmosphere of argon to obtain BTO; note here: the product must be completely cooled before being transferred out of the inert atmosphere, otherwise the highly active BTO may spontaneously combust when encountering air.

[0079] 2. The BTO was subjected to loading modification by the impregnation-photoreduction method, and the specific steps were as follows:

[0080] (1) Disperse 1 g of the obtained BTO in a solution containing a ruthenium precursor. Use ruthenium acetylacetonate as the ruthenium precursor; use acetone as the solvent. The actual ruthenium content in the solution is configured according to the required ruthenium mass ratio (5%). The suspension formed by BTO and the precursor solution is uniformly mixed after 30 minutes of ultrasonic treatment, and then transferred to a magnetic stirrer and stirred for 4 hours so that the ruthenium precursor is fully adsorbed on the carrier BTO;

[0081] (2) Subsequently, transfer the suspension to a rotary evaporator and remove the solvent by vacuum distillation in a 40 °C water bath to obtain a catalyst precursor;

[0082] (3) Place the catalyst precursor in a quartz reactor and perform photoreduction in a reducing atmosphere. The reducing atmosphere is a hydrogen-argon mixture (ratio 1:1, total flow rate 100 mL / min), the reduction temperature is 350 °C, and the reduction time is 8 h. After reduction, a Ru / BTO catalyst with a loading of 5 wt% is obtained. Among them, during the reduction process, the xenon lamp is the only light source, the temperature control is tested by directly contacting the surface of the catalyst with a thermistor probe, the gas flow rate is controlled by an electronic flowmeter, and the reactor carrying the catalyst is made of quartz.

[0083] Comparative Example 1

[0084] This comparative example provides a specific preparation method of unmodified Ru / TiO2, and uses the impregnation-photoreduction method to modify the unmodified TiO2. The specific steps are as follows:

[0085] (1) Disperse 1 g of unmodified TiO2 in a solution containing a ruthenium precursor. Use dodecacarbonylruthenium as the ruthenium precursor; use tetrahydrofuran as the solvent. The actual ruthenium content in the solution is configured according to the required ruthenium mass ratio (1 wt%). The suspension formed by unmodified TiO2 and the ruthenium precursor solution is uniformly mixed after 40 minutes of ultrasonic treatment, and then transferred to a magnetic stirrer and stirred for 4 hours so that the ruthenium precursor is fully adsorbed on the unmodified TiO2.

[0086] (2) Subsequently, transfer the suspension to a rotary evaporator and remove the solvent by vacuum distillation in a 60 °C water bath to obtain a catalyst precursor.

[0087] (3) Place the catalyst precursor in a quartz reactor and perform photo-reduction in a reducing atmosphere. The reducing atmosphere is a hydrogen-argon mixture (the volume ratio of hydrogen to argon is 1:3, and the total flow rate is 100 mL / min). The reduction temperature is 200 °C, and the reduction time is 8 h. After reduction, a Ru / TiO2 catalyst with a ruthenium nanoparticle loading of 1 wt% is obtained. During the reduction process, the xenon lamp is the only light source. The temperature is controlled by directly contacting the catalyst surface with a thermistor probe. The gas flow rate is controlled by an electronic flow meter. The reactor carrying the catalyst must be made of quartz.

[0088] Structural characterization and performance testing

[0089] Structural characterization: (1) The X-ray diffraction patterns of the Ru / BTO with a ruthenium nanoparticle loading of 1 wt% obtained in Example 1 and Ru / TiO2 in Comparative Example 1 are shown in Figure 1 , it can be seen that the modified Ru / BTO is an amorphous structure, while the X-ray diffraction pattern of the unmodified Ru / TiO2 shows diffraction signals attributed to TiO2. No Ru-related signals are seen in the X-ray diffraction patterns of both, indicating that the size of the Ru nanoparticles is small.

[0090] (2) The high-resolution transmission electron microscopy image of Ru / BTO with a ruthenium nanoparticle loading of 1 wt% is shown in Figure 2 , it can be seen that its lattice structure completely disappears, presenting an amorphous state, which is consistent with the results of X-ray diffraction. The scanning transmission electron microscopy image and energy-dispersive X-ray elemental distribution map of Ru / BTO with a ruthenium nanoparticle loading of 1 wt% are shown in Figure 3 , which shows that the Ru nanoparticles are uniformly loaded on the surface of the support BTO.

[0091] (3) Identification of active sites on the catalyst surface

[0092] In order to identify the special active sites on the surface of the Ru / BTO catalyst, solid-state nuclear magnetic resonance and electron paramagnetic resonance characterizations were performed on the Ru / BTO catalyst. The results are shown in Figure 6 and Figure 7。Solid-state nuclear magnetic resonance results show that there are a large number of surface hydroxyl groups Ti-OH and titanium-hydrogen bonds Ti-HOV on the surface of Ru / BTO, which are novel active sites not present in conventional titanium dioxide-supported catalysts. Electron paramagnetic resonance results further show that the titanium-hydrogen bond exists in the form of hydrogen-carrying oxygen vacancies. In the electron paramagnetic resonance spectrum, fine structure splitting of the signal appears, attributed to oxygen vacancies doped with hydrogen, i.e., Ti-HOV, which is also a novel active site not present in conventional oxygen vacancy-type catalysts. The hydrogen in Ti-HOV on the catalyst surface carries partial negative charge and is a Lewis base; the hydrogen in Ti-OH carries partial positive charge and is a Lewis acid, Ti-HOV and Ti-OH. The two are not connected by chemical bonds but are in a discrete state in space, forming a frustrated Lewis acid-base pair Ti-HOV···Ti-OH. This active site can directly activate an oxygen atom in gaseous carbon dioxide to generate water and carbon monoxide. In a hydrogenation atmosphere, ruthenium nanoparticles supported on the BTO surface can efficiently activate hydrogen to produce hydrogen spillover, and the hydrogen spillover further hydrogenates the BTO surface to replenish the consumed Ti-HOV···Ti-OH. Based on this, the synergistic effect of supported ruthenium nanoparticles and black titanium dioxide reverses the methane selectivity of conventional ruthenium-based catalysts in the photothermal reduction of carbon dioxide, making the catalyst have excellent activity and carbon monoxide selectivity in the carbon dioxide reduction reaction.

[0093] Performance test <{

[0094] 1. Photothermal activity test of the catalyst: Place the catalyst in a quartz reactor, introduce carbon dioxide and hydrogen with a volume ratio of 1:1, and then measure the temperature on the catalyst surface under simulated sunlight irradiated by a xenon lamp as the light source. The results are shown in Figure 4 , and the results show that the temperature on the catalyst surface can rise above 200 °C under illumination. As the temperature increases, the activity of the catalyst for the photothermal catalytic reduction of carbon dioxide to produce carbon monoxide also increases, and the activity can reach more than 10 mmol CO / g catalyst / hour. From Figure 5 It can also be seen that the carbon monoxide selectivity of Ru / BTO obtained in Example 1 is much higher than that of Ru / TiO2 in Comparative Example 1, while Ru / TiO2 mainly produces methane.

[0095] Obviously, the above examples are only for clear illustration and not a limitation of the implementation mode. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation modes here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A ruthenium-loaded black titanium dioxide composite material, characterized in that, Using black titanium dioxide as a carrier and ruthenium nanoparticles supported on the surface of the carrier, the surface of the carrier contains Ti-HOV···Ti-OH frustrated Lewis acid-base pairs; wherein, Ti-HOV is a hydrogen-oxygen vacancy; the preparation method of the black titanium dioxide composite material loaded with ruthenium nanoparticles comprises the following steps: Mix p25 titanium dioxide and a reducing agent, subject the obtained mixture to light grinding, and then heat and calcine to obtain a black powder; Mix the obtained black powder with water for reaction, perform solid-liquid separation to take the solid phase, and irradiate and dry the obtained solid phase in an inert atmosphere to obtain modified titanium dioxide BTO; Disperse the modified titanium dioxide BTO in a ruthenium precursor solution to obtain a suspension; remove the solvent in the suspension to obtain a precursor; Perform light reduction on the precursor in a reducing atmosphere to obtain the black titanium dioxide composite material loaded with ruthenium nanoparticles; The reducing agent is selected from one or more of sodium borohydride, potassium borohydride, lithium aluminum hydride, sodium hydride, and lithium hydride; The temperature of heat calcination is 300-500 °C, and the time is 60-120 minutes.

2. The black titanium dioxide composite material loaded with ruthenium nanoparticles according to claim 1, wherein, The loading amount of the ruthenium nanoparticles is 0.5 wt% - 5 wt%; The average particle size of the ruthenium nanoparticles is 2-5 nanometers.

3. A ruthenium nanoparticle-loaded black titanium dioxide composite material according to claim 1, characterized in that, The mass ratio of the p25 titanium dioxide to the reducing agent is 1:(2-4).

4. A ruthenium nanoparticle-loaded black titanium dioxide composite material according to claim 1, characterized in that, The ruthenium precursor in the ruthenium precursor solution is selected from one or more of dodecacarbonylruthenium, ruthenium chloride, ruthenium acetylacetonate, and ruthenium acetate; The solvent of the ruthenium precursor solution is selected from one or more of methanol, ethanol, tetrahydrofuran, acetone, and cyclohexane; The ruthenium concentration in the ruthenium precursor solution is 100-2000 ppm; The non-reactive gas in the inert atmosphere is selected from one or more of nitrogen, argon, helium, and neon; The light source in the light drying is infrared light, and the light irradiation time is 1-3 hours.

5. A ruthenium nanoparticle-loaded black titanium dioxide composite material according to claim 1, wherein, The reducing gas in the reducing atmosphere includes hydrogen and a non-reactive gas, and the non-reactive gas is selected from one or more of nitrogen, argon, helium, and neon; The volume ratio of the hydrogen to the non-reactive gas is (3:1)-(1:3); The total gas flow rate in the reducing atmosphere is 50-100 mL / min; The temperature of light reduction is 200-280 °C, and the time is 4-8 h.

6. Application of the black titanium dioxide composite material loaded with ruthenium nanoparticles according to any one of claims 1-5 in the photocatalytic reduction of carbon dioxide to carbon monoxide, and a mixed gas of carbon dioxide and hydrogen is introduced in the photocatalytic reaction.

7. The application according to claim 6, wherein Wherein, The volume ratio of the carbon dioxide to the hydrogen is (4:1)-(1:4); The reaction temperature in the photocatalytic reaction is greater than or equal to 200 °C.

8. The application according to claim 6, characterized in that, Before the photocatalytic reaction, the black titanium dioxide composite material loaded with ruthenium nanoparticles needs to be activated, and the activation conditions are: under the condition of 180-300 °C, light irradiation in a reducing atmosphere for 6-8 hours.

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