Preparation And Photocatalytic Activity Of AgMO₂（M=Al、Ga、In） Serial Composite Oxides

Abstract:In recent years, the traditional photocatalyst represented by TiO2can be used to degrade environmental pollutants with obvious effects. However, because of its wide bandgap (3.2eV for anatase), the weak visible light absorption ability and easy recombination of photogenerated electron-hole pairs, which largely limits its practical applications. Therefore, the research on developing the new photocatalysts with high activity under visible light to deal with environmental pollutants has become one of hotspots in the field of photocatalysis.In this paper, AgMO2(M=Al、Ga、In) serial composite oxides were taken as the research objects, which were modified using noble metal doping and semiconductor compositing, and AgAlO2/TiO2heterojunction photocatalyst, Ag/AgGaO2plasma catalyst and ZnO/Ag/AgInO2composite photocatalyst were prepared. The photocatalytic activity of the photocatalysts materials were investigated under visible light irradiations, and the possible potocatalytic mechanism of AgAlO2/TiO2heterojunction has been discussed. The main contents are summarized as follows:(1) The heterojunction photocatalysts AgAlO2/TiO2were synthesized by combining the sol-gel method with ion exchange method. The effects of doping amount and crystal type of TiO2on the photocatalysis of as-prepared samples were studied. The results demonstrated that the heterostructure was beneficial to the separation of photo-electrons and holes, which could enhance the photocatalytic activity and the as-synthesized AgAlO2/TiO2(anatase) in mass ratio of90/10exhibited the highest photocatalytic activity of97.8%under the visible light irradiation for90min.(2) The AgGaO2was prepared by hydrothermal method and ion exchange method, respectively. The effects of the reaction time and temperature on the synthesis of samples were investigated in the hydrothermal experiments. The results showed that a-AgGaO2was obtained when the reaction temperature is180℃and reaction time is60h. The effects of molar ratio of the raw material on the structure and property of samples were researched. The results indicated that the existence of Ag was conducive to improving the photocatalytic activity. When the molar ratio of AgNO3and NaGaO2was1.5, the as-synthesized Ag/AgGaO2exhibited the highest photocatalytic activity of95.0%under the visible light irradiation for180min.(3) The ZnO/Ag/AgInO2composite photocatalysts were synthesized by impregnation method. The XRD results indicated that doping of Zn can not change the crystal structures of Ag/AgInO2. The XPS illustrated that Zn2+existed as ZnO. The DRS showed that ZnO/Ag/AgInO2enhanced the intensity of visible-light absorption compared with Ag/AgInO2. The ZnO/Ag/AgInO2exhibited the higher photocatalytic activities for degradation of MB under visible-light irradiation. The highest effieieney was obtained When the sample calcined at400℃with10wt.%ZnO under visible-light irradiation for210min.