The Study On Visible Light Driven Photocatalytic Synthesis Of Hydrogen Peroxide At Triphasic Interface

Hydrogen peroxide(H2O2),as a green oxidant,has been widely used in organic industrial synthesis,water pollution treatment and other industrial fields.Currently,the commonly used routes for H2O2 synthesis are anthraquinone oxidation and direct product by hydrogen and oxygen,but they generally require large amount of energy input and endanger the environment.Photocatalytic synthesis of H2O2 based on semiconductor which can utilize clean solar energy,water and oxygen(O2)as reactants,has attracted much attention and been widely studied.Under light illumination,photogenerated electrons reduce O2 on the catalyst surface and react with H+to form H2O2.The nobel metal with local surface plasmon resonance(LSPR)effect decorated semiconductor is a kind of ideal visible light active catalysts.Nobel metals can absorb visible light and act as a co-catalyst to promote the reduction of O2 to H2O2.However,in traditional photocatalytic system,photocatalytic reaction occurs at the solid-liquid interface,the reactant O2 can only be supplied through the liquid phase.Due to the limited solubility and diffusion coefficient of O2 in the liquid phase,O2 concentration at the reaction interface is usually very low,which limits the H2O2 production rate.In addition,the low interface oxygen level will result in high electron-hole pair recombination and low light energy utilization efficiency.In this work,in order to address the above problem,we construct an efficient photocatalytic reaction system with an air-liquid-solid triphasic reaction interface microenvironment.O2 can directly transport to the reaction interface from the air phase,which greatly improves the O2 concentration at the reaction zone,and increases the H2O2 yield.The results indicate that in addition to the photocatalyst materials,the rational design and construction of reaction interface microenvironment play a key role in the photocatalytic reaction performance.The research content of this paper includes the following two parts:Part I.Construction of triphasic interfacial photocatalytic system.In this chapter,Au decorated TiO2(Au-TiO2)photocatalyst with visible light activity was prepared by adsorption-reduction method,and a triphasic interfacial photocatalytic system was constructed by using surface wettability regulation.Part Ⅱ.Performance of visible-light-driven H2O2 synthesis based on the as-constructured triphase interfacial photocatalytic system.Based on the triphase interfacial photocatalytic system,the reaction kinetics of H2O2 synthesis by using Au-TiO2 photocatalyst under different light intensities was studied,and the effect of the triphase interface microenvironment on the reaction rate was discussed.The results reveal that the rational design and construction of interfacial microenvironment is of great improtance to the performance of photocatalytic synthesis H2O2.