锰离子控制掺杂二氧化钛薄膜光催化活性增强的机理探讨

Mechanism for Enhanced Photocatalytic Activity of Titanium Dioxide Film Doped by Mn Under Control

采用溶胶-凝胶法通过工艺控制制备了锰离子以不同形式掺杂TiO2的光催化剂薄膜,并通过XPS和SEM对薄膜的结构进行表征.通过UV-V is分光光度计及电化学工作站表征了薄膜的光吸收性能和光电化学性能,通过甲基橙溶液的光催化降解脱色率来表征催化剂薄膜的光催化活性.结果表明,以锰离子MT掺杂方式制备的TiO2薄膜可明显增强TiO2的光催化活性,而以MM掺杂方式制备的TiO2薄膜反而降低了TiO2的光催化活性;锰离子MT掺杂方式的最佳掺杂质量分数为0.8%.催化剂薄膜的电化学行为显示,薄膜具有p-n结的电容-电压特性,锰离子MT掺杂TiO2薄膜的开路电位和瞬时光电流信号较强,说明其光生载流子易于生成并且分离效果较好.依据半导体的p-n结原理探讨了锰离子控制掺杂TiO2的光催化活性机理.

The thin films of TiO2, doped by Mn with different doping modes, were prepared by sol-gel method under process control. The structure of the films was characterized by XPS and SEM. The thin films were evaluated by UV-Vis spectrophotometer and electrochemical workstation. And the activity of the photocatalyst was evaluated by photocatalytic degradation of aqueous methyl orange under UV radiation. The results show that the photocatalytic activity of TiO2 thin film can be evidently enhanced by MT doping mode with the optimal dopant mass fraction of 0.80%, on the contrary, decreased by MM doping mode. The characteristic of capacitance-tension characteristic of p-n junction in the film was proved by electrochemical characterization. A mechanism for enhanced photocatalytic activity of titanium dioxide film doped by MT mode was discussed in terms of semiconductor p-n junction theory.