ZnO/Ag2CrO4复合物的光催化降解特性及其Z型电子传输光催化机理

Photocatalytic Characteristics of ZnO/Ag2CrO4 Composite and Its Photocatalytic Mechanism with Z-scheme of Electron Transport

采用水热法和光沉积法制备了Ag2CrO4纳米片复合的La掺杂ZnO纳米棒(ZnO/Ag2CrO4),并以甲基橙(MO)为降解物,考察了ZnO/Ag2CrO4复合物的光催化性能。结果表明,Ag2CrO4复合使ZnO晶体的本征吸收边产生了红移,并且增强了对可见光的吸收率,从而提高了ZnO对太阳光的利用率,有效地提升了其光催化效率。ZnO/Ag2CrO4复合物的光催化效率在一定范围内随着Ag2CrO4在复合物中含量的增多而增强。当Ag^+的光沉积浓度为Zn源浓度的6%时,复合物的光催化效率达到最佳,进一步提高Ag^+的光沉积浓度时,则形成Ag2CrO4过量的复合物,导致复合物的光催化效率开始下降。结合UV-Vis和PL测试,推导出复合物的光催化机理中,光生电子的传输机制为Z型传输机制,从而抑制了光生电子-空穴对的复合,延长了激子的寿命,提高了复合物的光催化效率。

The La-doped ZnO nanorods composited with Ag 2CrO 4 nanosheets(ZnO/Ag2CrO4)were prepared by a hydrothermal method followed by a photo-deposition process.And the photocatalytic properties of the ZnO/Ag2CrO4 composite were examined by a degradation of methyl orange(MO)solution at room temperature.In the investigation of absorption properties of the ZnO/Ag 2CrO 4 composite,an obvious red-shift of the intrinsic absorption edge of ZnO was observed,which was induced by the composited Ag2CrO4 nano-sheets.Therefore,compared with pure ZnO,the utilization rate of solar light was improved effectively by the composite,which was beneficial to the elevation of the photocatalytic efficiency.Furthermore,the photocatalytic efficiency of the composite increased with the increasing of the content of the Ag 2CrO 4 nano-sheets in the composite,and the optimum photocatalytic efficiency appeared in the sample prepared with the Ag^+concentration being 6%of Zn source concentration during photo-deposition process.When the Ag^+concentration was further increased,the excess Ag2CrO4 was produced,which led to degradation of photocatalytic efficiency.Based on the measurements of UV-Vis and PL spectra,a Z-type scheme electron transport mechanism was deduced in the ZnO/Ag2CrO4 composite during photocatalytic process,by which the recombination of electron-hole pairs was inhibited,thus the lifetime of excitons was prolonged.Therefore,the photocatalytic efficiency of the composite was dramatically improved.