The Research On The Photocatalytic Activity Of Ag/TiO₂ Composite Films By Plasma Irradiation

Photocatalytic technology is a newly arisen environment friendly technique,whose advatages are high efficiency,simple,mild operating condition,degradation organics pollution without selectivity and without second pollution.However,in practical application,photocatalytic materials have many limitations including low photo catalysis activity,low efficiency in using solar energy etc.In this paper,AgNPs/TiO₂ composite films were prepared,and the process and mechanism of the photocatalytic efficiency of the composite films were studied by oxygen plasma and air plasma irradiation.First,The TiO₂ films with different thickness were prepared by vacuum evaporation method and mix the same amount of AgNPs,The effect of TiO₂ thickness on photocatalytic efficiency was studied.Results show the photocatalytic efficiency of the composite films increases with the increase of Ti O₂ thickness.AgNPs/TiO₂ composite films were treated by air plasma irradiation,The photocatalytic efficiency before and after irradiation and the effect of irradiation time on the photocatalytic efficiency were studied.Results show the photocatalytic efficiency of the composite films increased in different degree after different air plasma irradiation time,and the photocatalytic efficiency was the best when the air plasma was irradiated with 20 s.Then,the AgNPs/TiO₂ composite films were treated by oxygen plasma irradiation.The photocatalytic efficiency before and after irradiation and the effect of irradiation time on the photocatalytic efficiency were studied.It was found that the photocatalytic efficiency was optimized after oxygen plasma irradiated 5s.SEM,TEM and XPS tests were performed on the part of the sample.According to the test results,the AgNPs on TiO₂ surface was partial oxidized by the oxygen plasma irradiation,and form a Ag₂O/AgNPs/TiO₂ structure.Because the plane spacing between Ag₂ O formed perfect oxygen plasma irradiation process strongly damped with AgNPs and Ag₂ O,under visible light irradiation,hot holes can be transferred from the AgNPs to the instantaneous Ag₂ O,so as to enhance the photocatalytic efficiency of AgNPs/TiO₂ composite films after partial oxidation.In this study,the research on the photocatalytic mechanism of AgNPs/TiO₂ composite films is of scientific significance,which promotes the practical process of photodegradation of pollutants.