Study On The Synergistic Reaction Of CO₂ Reduction And Selective Oxidation Of Aromatic Alcohols With Zn_XCd_1-XS Based Catalyst

Carbon dioxide is the most abundant and cheapest source of carbon and can be converted into valuable chemicals such as fuels(methane,methanol,ethanol,carbon monoxide),polymers(polycarbonate)and valuable industrial compounds(formic acid,carbonic acid).The market for these compounds is about 450 million tons per year.Therefore,the development of carbon dioxide has aroused the interest of the scientific community and industry,and a lot of efforts have been made to develop efficient conversion systems.Since the photocatalytic technology was first reported in the 1980s,it has achieved fruitful results and applications in the aspects of photocatalytic hydrogen production,nitrogen fixation,organic synthesis and pollutant degradation.Therefore,the conversion of CO₂ using photocatalytic technology has great application prospects.Based on this,the work of this paper mainly focuses on the construction of the synergistic reaction system of photocatalytic CO₂ reduction and selective oxidation of aromatic alcohols,the preparation of efficient catalysts and the reaction mechanism.The main research contents of this paper are as follows:1.Zn_xCd_1-xS nanoparticles with different compositions were successfully prepared by hydrothermal method,and the synergistic reaction system of photocatalytic CO₂reduction and selective oxidation of aromatic alcohols was successfully constructed.The results showed that Zn_0.3Cd_0.7S exhibited high reactivity in the synergistic reaction of catalytic CO₂ reduction and selective oxidation of 4-chlorobenzyl alcohol,with hydrogen production rate of 784?mol·g^-1·h^-1 and CO production rate of 67?mol·g^-1·h^-1,respectively.In addition,the formation rate of 4-chlorbenzaldehyde reached 908?mol·g^-1·h^-1.The results show that the Zn vacancy can increase the reaction rate of photocatalytic reaction.2.Different proportions of g-C₃N₄/Zn_0.3Cd_0.7S materials were successfully prepared by self-assembly method.The results showed that 3%g-C₃N₄/Zn_0.3Cd_0.7S had the best reactivity.The hydrogen production rate and CO production rate reach 35?mol g^-1·h^-1 and 150?mol·g^-1·h^-1,respectively.Further studies show that g-C₃N₄ and Zn_0.3Cd_0.7s have N and Zn vacancy structures,respectively.It can be seen that the construction of more vacancy structures can provide more active sites for the reaction,which is conducive to the occurrence of the synergistic reaction of photocatalytic CO₂reduction and selective oxidation of aromatic alcohols.3.Based on the above research results,we explored the influence of different vacancy structures on photocatalytic reaction,and successfully prepared In₂S₃/Zn_0.3Cd_0.7S materials with different proportions by self-assembly method.The results showed that 3%In₂S₃/Zn_0.3Cd_0.7S had the best reactivity.The hydrogen production rate and CO production rate reach 44?mol g^-1·h^-1and 133 umol·g^-1·h^-1,respectively.In addition,we also tried to use different raw materials to control the formation of S vacancy,so as to prove the role of vacancy in catalytic reaction.