Construction Of Three-phase Interface And Study On Photocatalytic Properties

Environment protection and energy crisis are the big concerns in the 21st and we human beings should take sensible measures to address these pressing issues as soon as possible.Photocatalytic technology based on semiconductor using solar energy which is a clean and sustainable resource is a good approach to degradate and mineralize a variety of organic pollutants and convert and store energy and etc.More efforts should be made in this field and we strongly believe that it is a far-reaching work for the sustainable development economy and ecosystem and our human society.Photocatalytic technology uses semiconductor light absorption to generate electrons and holes,and oxygen reduction reaction occurs with the corresponding capture agent respectively,to achieve organic degradation,energy conversion and storage applications.With the rapd development of nanotechnology,photocatalysis research has made a lot of progresses.Currently,photocatalytic reaction is facing a big challenge for the sake of charge recombination.Oxygen is a natural electron acceptor,it plays an important role in photocatalytic degradation of organic pollutants and photocatalytic synthesis.Its reaction with electrons not only affects photogenic charge recombination directly but also lead to the production of a variety of reactive oxygen species participating in organic degradation and energy conversion and other processes.However,the traditional photocatalytic reaction usually takes place at the solid-liquid interface where oxygen level is greatly limited by its low solubility and low transmission rate in the liquid.So this paper aims to change the photocatalytic reaction in traditional solid-liquid two-phase,introducing the gas phase to construct the solid-liquid-gas tri-phase reaction interface.The newly built gas channels on the catalyst surface improve the oxygen mass transfer rate and then the efficiency of electron acceptor,charge separation as well as the quantum efficiency are improved accordingly.The work is mainly divided into two parts:The first part is to construct the solid-liquid-gas tri-phase photocatalytic system for organic degradation.Oxygen can be quickly transferred from the gas phase to the reaction interface,so as to react with electrons in time,reduce the recombination,and generate reactive oxygen to promote degradation.Compared with the conventional solid-liquid bi-phase system,the photocatalytic reaction rate is about 10 times higher.What’s more high quantum efficiency can be maintained even at pretty high light intensity(photoelectron density).The second part is the efficient synthesis of hydrogen peroxide based on solid-liquid-gas tri-phase interface.The tri-phase system enables sufficient reactant oxygen to reach the photocatalyst/water interface directly from the ambient atmosphere,greatly enhancing the reaction kinetics of hydrogen peroxide formation.The gas phase transport of interfacial oxygen effectively inhibits the recombination and degradation of electron holes and further improves the quantum yield.Compared with the traditional reaction system,the tri-phase interface structure increased the synthesis concentration of hydrogen peroxide by 44 times.