低温吸附制备Au-TiO_2复合薄膜及其光电化学性质

摘要

Au-TiO_2 nanocomposite films were prepared by adsorbing prefabricated Au colloids on TiO_2 films at low temperature. The Au-TiO_2 films were characterized with ultra-high resolution FESEM, XRD and XPS, and their photoelectrochemical properties were measured under UV illumination. Au nanoparticles with an average diameter of (4.3±1.2) nm were homogeneously dispersed on the TiO_2 films with high loading. The photoelectrochemical measurements showed that the photocurrent of TiO_2/Ti electrode was improved about 5 folds, and the photovoltage significantly increased to more negative values after depositing Au nanoparticles. It indicates that Au nanoparticles have the beneficial role in improving the photoinduced charge separation efficiency and promoting the charge transfer at the interface between the electrode and electrolyte. The electrochemical impendence spectroscopy (EIS) analyses revealed that the resistance of charge transfer(R_α) of Au-TiO_2/Ti electrode was reduced to half of that of TiO_2/Ti, indicating that the carrier density in the Au-TiO_2/Ti electrode is increased by suppressing the recombination of photogenerated hole-electron pairs.%在低温条件下将预先合成的Au溶胶吸附到TiO_2薄膜上以制备纳米Au-TiO_2复合薄膜,以超高分辨率场发射扫描电镜(FESEM)、X射线衍射(XRD)及X射线光电子能谱(XPS)表征Au-TiO_2膜,并在UV辐照下测定了Au-TiO_2薄膜电极的光电化学性质.纳米Au呈金属态,平均粒径为(4.3±1.2)nm,负载量高,均匀地沉积于TiO_2薄膜表面.光电化学测试表明,沉积纳米Au后,TiO_2电极的光生电流提高近5倍,光生电压明显向负值增大,说明纳米Au可增强光生载流子的分离效率,促进电荷在电极与溶液界面间的转移.Au-TiO_2电极的电荷传递法拉第阻抗(R_α)是TiO_2电极的一半,说明负载的纳米Au粒抑制了光生电子-空穴的复合,提高了电极中载流子浓度.