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Small: tailoring of visible light photocatalyst: from photocatalytic hydrogen production to photoreduction of CO2

wallpapers News 2020-10-02
In recent years with the transition development utilization of fossil energy

has led to the transition emission of CO2 which has seriously affected the balance of natural carbon cycle brought very serious environmental problems especially the climate change caused by greenhouse effect. CO2 reduction reaction (co2rr) is an effective way to synthesize high value-added chemicals from excessive CO2 emissions. This process can not only reduce the content of CO2 in the atmosphere but also store renewable energy in the reduction products for reuse maintain the carbon balance of nature. However CO2 molecule is very stable (804.4 kJ mol-1) the conversion of CO2 to hydrocarbon is a non spontaneous reaction (△ g > 0) which makes the reduction of CO2 very difficult. Photocatalytic CO2 reduction provides us with a new idea. "Photocatalytic CO2 reduction" refers to the use of solar energy to reduce CO2 into carbon compounds such as carbon monoxide methane ethylene etc. which are stable efficient clean energy for people's daily use. In this way we can not only alleviate the global energy crisis but also realize the "carbon cycle" really use the excessive CO2 in the atmosphere to industrial life.

the research team of Zhang Jiatao of Beijing University of technology aiming at the performance tailoring of plasma enhanced photocatalyst combined the original non epitaxial growth method with epitaxial growth method realized the performance leap from metal / semiconductor hetero nanocrystalline photocatalysis for hydrogen production (her) to CO2 RR. Firstly dumbbell structure Au / CdSe heterostructures were synthesized by reverse competitive cation exchange reaction. The results show that Au / CdSe heterostructures have single crystal CdSe semiconductor shell clear metal / semiconductor heterostructure interface plasma enhanced hot electron injection efficiency high her activity. The researchers further regulated the performance of the photocatalyst obtained Au / cdse-cu2o multilayer heterostructure nanocrystals with clear heterostructure interface by epitaxial growth method. Therefore the Au / cdse-cu2o multilayer heterostructures have high co2rr activity the selectivity of carbon containing products is as high as 100%. It is found that the product of photocatalytic reduction of CO2 is closely related to the photocatalytic reaction conditions. Under the condition of ensuring high selectivity of carbon containing products the ratio yield of 2-electron reduction product CO 8-electron reduction product CH4 can be effectively adjusted by adjusting the content of H2O in the photocatalytic reaction system. The results show that CdSe Cu2O form a Z-scheme heterostructure which promotes the separation of photogenerated charges improves the photocatalytic performance of CO2 reduction. The LSPR effect of Au nanorods improves the light absorption performance of the whole photocatalyst provides an electric field environment to accelerate the transfer of photogenerated charge; Cu2O around the heterostructure has rich oxygen vacancies hydroxyl groups which improves the adsorption performance of CO2 provides abundant active sites for photocatalytic reaction; CdSe semiconductor in the middle as a bridge of photogenerated charge transfer improves the efficiency of photocatalysis The transfer efficiency of photogenerated charge is studied. Under the optimal photocatalytic conditions the stable formation rates of CO CH4 in Au / cdse-cu2o multilayer heterostructures within 60 hours are 254 123 μ mol g-1 H-1 respectively.

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