Cu2O / CuSiO3 hollow nanosphere as well as preparation method and application thereof

Abstract

The invention discloses a Cu2O / CuSiO3 hollow nanosphere as well as a preparation method and application thereof, and the preparation method comprises the following steps: firstly synthesizing a copper silicate material through a precipitation method, then directly placing the copper silicate material in a photo-thermal catalytic reaction device, and carrying out photo-thermal catalytic CO2 hydrogenation reaction at the reaction temperature of 200-300 DEG C to synthesize the Cu2O / CuSiO3 hollow nanosphere in situ. The Cu2O / CuSiO3 hollow nanosphere can be used as a photo-thermal catalyst, has good stability and excellent catalytic performance, and has the characteristics of high CO generation rate and high selectivity in photo-thermal catalysis of CO2 hydrogenation reaction. The raw materials for preparing the Cu2O / CuSiO3 hollow nanospheres are cheap and easy to obtain, the synthesis process is simple and easy to operate, and no harsh experimental conditions exist.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials, and particularly relates to a Cu2O / CuSiO3 hollow nanosphere, a preparation method thereof, and an application thereof. Background Art

[0002] Under the severe situation of global climate change, the excessive emission of CO2 leads to the intensification of the greenhouse effect, and traditional energy sources are increasingly scarce. It is urgent to develop new green energy sources. Catalytically converting CO2 into high-value useful chemicals is an effective strategy for the current resource utilization of CO2. Industrially, thermal catalytic technology is often used to catalytically hydrogenate CO2 to synthesize products such as CH3OH and CO. However, this process needs to be realized under harsh conditions such as high pressure and high temperature. Photocatalytic CO2 reduction technology can directly utilize solar energy and can drive redox reactions under normal pressure and room temperature conditions. However, due to the limited quantum efficiency and solar energy utilization rate, the overall photocatalytic CO2 reduction performance is difficult to compare with thermal catalysis. The photo-thermal catalytic CO2 hydrogenation technology that combines thermal catalysis and photocatalytic technology can utilize solar energy to lower the reaction barrier and can also complete the reaction under milder (normal pressure, low temperature) conditions. In the photo-thermal catalytic CO2 hydrogenation reaction, developing a catalyst with high activity, high selectivity, and high stability is a key requirement. To make this process commercially feasible, it must also meet the following requirements: the photocatalyst has abundant reserves, low cost, non-toxicity, and can absorb solar photons in a wide spectral range.

[0003] In order to obtain chemical substances with higher utilization value, researchers have adopted different experimental schemes to prepare different catalysts according to the characteristics of materials or to achieve this goal by controlling the conditions of CO2 hydrogenation. For example, first synthesizing a substrate material and then introducing metals such as Au, Pd, Rh, and Pt in a loaded manner can effectively improve the CO2 hydrogenation activity or optimize the selectivity for high-value chemical products; or a series of In2O3 photocatalysts are prepared by hydrothermal method, and some semiconductor materials are compounded or loaded on the basis of In2O3 to achieve the improvement of activity and the transformation of products. In short, most photocatalytic materials usually require a cumbersome and harsh preparation process or are synthesized with the assistance of high-temperature and high-pressure experimental conditions, which greatly hinders their industrialization process and does not have the potential for large-scale industrialization. In addition, during the photo-thermal catalytic CO2 hydrogenation reaction process, the existing catalysts are usually affected by reaction conditions such as high temperature, H2 reduction atmosphere, and light, resulting in significant changes in the composition, structure, morphology, etc. of the catalyst, leading to a gradual decrease in the activity of the catalyst or even inactivation. Therefore, researchers intend to find a photocatalyst to provide preliminary tests and technical support for the industrial production of photo-thermal catalytic CO2 hydrogenation reaction.

[0004] Silicates are the most abundant resources in the earth's crust. They are composed of silicon and oxygen atoms as well as other metal elements. Metal-containing silicates are mainly composed of SiO4 tetrahedra and metal-oxygen polyhedra. Due to their special physical and chemical properties, silicates have been widely used in fields such as molecular sieves, catalyst carriers, and gas adsorption and separation. Moreover, silicate materials themselves have a rich pore structure and specific surface area, which is conducive to enhancing the adsorption capacity and reaction activity of catalysts. In recent years, there have also been a large number of reports on the applications of silicate nanomaterials in fields such as high-efficiency catalysts / catalyst precursors, luminescent matrix materials, biomedicine, energy storage, and wastewater treatment. Copper silicate (CuSiO3) is a typical silicate nanomaterial. In recent years, there have been endless reports on its composition optimization, structure regulation, and applications in multiple fields, but there has been no report on its research in the field of photocatalysis or photothermal catalysis. Summary of the Invention

[0005] Aiming at the problems existing in the above-mentioned background technology, the purpose of the present invention is to provide a Cu2O / CuSiO3 hollow nanosphere and its preparation method and application.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions: A preparation method of a Cu2O / CuSiO3 hollow nanosphere, comprising the following steps: S1. Dissolve sodium silicate (Na2SiO3), ammonium chloride (NH4Cl), and ammonia water (NH3·H2O) in deionized water to form solution A; S2. Dissolve copper chloride (CuCl2) in deionized water to form solution B; S3. Under room temperature conditions and strong stirring, slowly drop solution A into solution B, and continue to stir for a certain time, then centrifuge to collect the precipitate, wash and dry to obtain a copper silicate (CuSiO3) sample; S4. Load the obtained copper silicate (CuSiO3) sample into the quartz tube inside a micro-reaction device, and carry out a photothermal catalytic CO2 hydrogenation reaction at a reaction temperature of 200 - 300 °C to in-situ synthesize Cu2O / CuSiO3 hollow nanospheres.

[0007] Further, in step S3, the continuous stirring time is 12 hours.

[0008] Further, in step S4, the conditions of the photothermal catalytic CO2 hydrogenation reaction are: a continuous flowing CO2 / H2 mixed gas stream, 1 - 1.2 atmospheres, xenon lamp illumination with 5 - 20 sun energies, and the reaction is carried out for 0.5 - 6 hours. Preferably, 1 atmosphere, xenon lamp illumination with 5 sun energies, and the reaction for 1 hour.

[0009] Further, the flow rate ratio of the CO2 / H2 mixed gas stream is 1:3.

[0010] The present invention further provides Cu2O / CuSiO3 hollow nanospheres obtained by the above preparation method.

[0011] The present invention further provides the application of the Cu2O / CuSiO3 hollow nanospheres as a photothermal catalyst, and the Cu2O / CuSiO3 hollow nanospheres as a photothermal catalyst for the photothermal catalytic CO2 hydrogenation reaction.

[0012] Compared with the disadvantages and deficiencies of the prior art, the present invention has the following beneficial effects: (1) The raw materials are common, inexpensive and easily available silicates, chlorides, etc.; the synthesis process of the copper silicate material is simple, easy to operate, and there are no harsh experimental conditions; (2) In the present invention, the copper silicate material is first synthesized by the precipitation method, and then the copper silicate material is directly loaded into the photothermal catalytic reaction device. After a short-time in-situ pretreatment, a high-performance Cu2O / CuSiO3 hollow nanosphere catalyst can be obtained; (3) The photocatalytic material prepared by the present invention has good stability and excellent catalytic performance, and has the characteristics of high CO generation rate and high selectivity. Description of the Drawings

[0013] Figure 1 are the XRD spectra (a) and XPS spectra (b) of CuSiO3 and Cu2O / CuSiO3 hollow nanospheres provided in Example 1 of the present invention; Figure 2 are the SEM images (a), TEM images (b and c), HETEM image (d) and elemental mapping images (e) of CuSiO3 and Cu2O / CuSiO3 hollow nanospheres provided in Example 1 of the present invention; Figure 3 are the photothermal catalytic CO2 hydrogenation performances of Cu2O / CuSiO3 hollow nanospheres and reference samples provided in Example 2 of the present invention at different reaction temperatures. In the figure, a, b, and c represent the reaction temperatures of 200 °C, 250 °C, and 300 °C respectively; d is the Arrhenius plot of the CO formation rate of Cu2O / CuSiO3 at three temperature conditions; Figure 4 is the photothermal catalytic CO2 hydrogenation performance stability result of Cu2O / CuSiO3 hollow nanospheres provided in Example 2 of the present invention at 300 °C. Detailed Embodiments

[0014] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following specific embodiments are used to further describe the present invention in detail. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Embodiments

[0015] The preparation method of Cu2O / CuSiO3 hollow nanospheres is as follows: S1. Dissolve 1 mmol of Na2SiO3, 1 mmol of NH4Cl and 1 mL of NH3·H2O in 30 mL of deionized water to form solution A; S2. Dissolve 0.75 mmol of CuCl2 in 10 mL of deionized water to form solution B; S3. Slowly add solution A dropwise to solution B under room temperature conditions and strong stirring, and continue stirring for 12 hours. Then, centrifuge to collect the precipitate, wash it with deionized water multiple times, and then dry it at 60 °C for 12 hours to obtain the CuSiO3 sample; S4. Place the obtained CuSiO3 sample inside the quartz tube of a micro-reaction device, and react for 1 hour under the conditions of a reaction temperature of 200 - 300 °C, a flow rate ratio of CO2 / H2 mixed gas flow of 1:3 (the flow rates of CO2 and H2 are 2 mL / min and 6 mL / min respectively), 1 atmospheric pressure, and xenon lamp illumination with 5 sun energies, and the hollow nanospherical Cu2O / CuSiO3 sample can be in-situ synthesized.

[0016] Product characterization test: 1. Perform XRD and XPS tests on the prepared Cu2O / CuSiO3 sample, and at the same time perform XRD and XPS tests on the CuSiO3 sample obtained in step S3 for comparison. The results are as Figure 1 shown. It can be seen that the finally synthesized material is a Cu2O / CuSiO3 composite material.

[0017] 2. Perform SEM, TEM and HRTEM tests on the prepared Cu2O / CuSiO3 sample. The SEM results are as Figure 2 shown in a, the TEM results are as Figure 2 shown in b and c, and the HRTEM results are as Figure 2 shown in d. Combining the test results of SEM and TEM, it can be known that the finally synthesized Cu2O / CuSiO3 sample is in the shape of hollow nanospheres; according to Figure 2 the elemental mapping diagram shown in e, it can be known that the finally synthesized sample is composed of three elements: O, Si, and Cu, further verifying the conclusion that the final product is a Cu2O / CuSiO3 composite material. Example

[0018] Use the Cu2O / CuSiO3 hollow nanospheres prepared in Example 1 as a photothermal catalyst, and at the same time use Cu2O / SiO2 and CuO / SiO2 as reference samples to carry out the photothermal catalytic CO2 hydrogenation reaction. The reaction temperatures are 200 °C, 250 °C, and 300 °C respectively. From Figure 3As shown in a-c, the rate of the photocatalytic hydrogenation of CO2 to CO over the Cu2O / CuSiO3 hollow nanospheres is much higher than that of the reference samples Cu2O / SiO2 and CuO / SiO2. The photocatalytic hydrogenation of CO2 over the Cu2O / CuSiO3 hollow nanospheres exhibits a remarkable CO production rate. From Figure 3 the Arrhenius plot of the CO production rate of Cu2O / CuSiO3 at the three temperature conditions shown in d, it can be seen that as the reaction temperature increases, the rate of CO production increases, and the rate of CO production is the highest when the reaction temperature is 300 °C.

[0019] The stability of the photocatalytic hydrogenation performance of the Cu2O / CuSiO3 hollow nanosphere sample at 300 °C was tested. The results of the reaction for 45 hours are as shown in Figure 4 shown. When the photocatalytic hydrogenation of CO2 was carried out at 300 °C for 45 hours, the rate of CO production did not show an obvious decrease. The photocatalytic hydrogenation performance of the Cu2O / CuSiO3 hollow nanospheres exhibits good stability.

[0020] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of Cu2O / CuSiO3 hollow nanospheres, characterized in that, It includes the following steps: S1. Dissolve Na2SiO3, NH4Cl and NH3·H2O in deionized water to form solution A; S2. Dissolve CuCl2 in deionized water to form solution B; S3. Under room temperature conditions and with strong stirring, slowly drip solution A into solution B, and after continuous stirring for a certain time, centrifuge to collect the precipitate, wash and dry to obtain the CuSiO3 sample; S4. Load the obtained CuSiO3 sample into the quartz tube inside the micro-reaction device, and carry out the photothermal catalytic CO2 hydrogenation reaction at a reaction temperature of 200 - 300 °C to in-situ synthesize Cu2O / CuSiO3 hollow nanospheres.

2. The preparation method of the Cu2O / CuSiO3 hollow nanospheres according to claim 1, wherein, In step S3, the continuous stirring time is 12 hours.

3. The preparation method of the Cu2O / CuSiO3 hollow nanospheres according to claim 1, wherein, In step S4, the conditions for the photothermal catalytic CO2 hydrogenation reaction are: a continuously flowing CO2 / H2 mixed gas stream, 1 - 1.2 atmospheres, xenon lamp illumination with 5 - 20 sun energies, and the reaction is carried out for 0.5 - 6 hours.

4. The preparation method of the Cu2O / CuSiO3 hollow nanospheres according to claim 3, characterized in that, The flow rate ratio of the CO2 / H2 mixed gas stream is 1:

3.

5. A Cu2O / CuSiO3 hollow nanosphere prepared by the preparation method according to any one of claims 1 - 4.

6. An application of the Cu2O / CuSiO3 hollow nanosphere according to claim 5 in the field of photothermal catalysis.

7. The application according to claim 6, wherein The Cu2O / CuSiO3 hollow nanosphere is used as a photothermal catalyst for the photothermal catalytic CO2 hydrogenation reaction.

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