Preparation Of Composite Photocatalysts Based On Lamellar Structure And Their Photocatalytic Performance For Reduction CO₂

With the advancing industrialization,we now face two pressing but unresolved issues:one is the energy shortage and the other is the deterioration of the environment.The increase of population and the continuous expansion of energy consumption have caused the supply of energy reserves.At the same time,the CO₂ emission has increased remarkably in the atmospheric.CO₂ is the main gas that causes the greenhouse effect,however,which also contains abundant carbon resources.Solar energy as a sustainable and clean energy source has attracted the interest of many experts and scholars.Therefore,it is important to convert solar energy to other energy sources.Photocatalytic reduction of CO₂ comes into being:on the one hand can ease the energy problem,on the other hand can reduce the concentration of CO₂ in the atmosphere,achieving sustainable development.This paper explores the preparation of several photocatalysts and the activity of photocatalytic reduction of CO₂,the main contents are as follows:Firstly,the graphene oxide was prepared by Hummers'method and reduced to graphene?Gr?by different reducing agents.Then the ZnO/Gr composite photocatalyst was successfully prepared.In this process,the effects of graphene on morphology and reduction degree were explored under different reaction conditions.And ZnO/30%Gr photocatalyst showed the highest photocatalytic activity and the rate of methanol can reach 2772.9?mol/h·g_cat.Secondly,the samples of ZnSe with different morphologies were synthesized by solvothermal method.The effects of different structure directing agents and different selenium sources were investigated.The photocatalytic activity was also evaluated and the results showed that ZnSe samples with sodium selenite as selenium source and hydrazine hydrate as structure-directing agent exhibited the highest photocatalytic activity and the rate of methanol can reach 667.8?mol/h·g_cat.Thirdly,ZnO/ZnSe composite photocatalyst was synthesized by solvothermal method.These two semiconductors formed type II heterojunction photocatalysts,which effectively transported photogenerated carriers and inhibited the photogenerated electron-hole recombination,increasing its photocatalytic reduction of CO₂ efficiency.Finally,combining the Mott-Schottky junction and electrochemical impedance spectroscopy?EIS?,the mechanism of photocatalytic reduction of CO₂ by ZnO/ZnSe photocatalyst in isopropanol was explored.