金离子掺杂对二氧化钛光催化性能的影响

Effect of Gold Ion Doping on the Photo-catalytic Properties and Photo- activity of TiO2

利用高压钠灯作光源,在Au3+-TiO2悬浮溶液中,通过紫外-可见吸光度与TOC测定证实亚甲基蓝能被快速脱色降解.金离子掺杂可大大提高TiO2的光催化活性,金离子的最佳掺杂摩尔分数为0.5%.通过表征催化剂的晶型,化学组成,荧光光谱,紫外-可见吸收光谱,电场诱导表面光电压谱,揭示金离子改性的机理.紫外-可见吸收光谱证实金离子掺杂可增强催化剂在可见光区域的吸收能力,由于产生金杂质能级,金离子改性TiO2能被可见光激发.适量的金杂质能降低催化剂的荧光发射强度与电场诱导表面光电压谱强度.根据不同金离子掺杂摩尔分数,荧光发射强度与电场诱导表面光电压谱强度从弱到强的排序与光催化活性从强到弱的排序是一致的.

Methylene Blue (MB) undergoes rapid mineralization in aqueous TiO2 dispersions with or without doping with gold ion upon radiation with visible light (high - pressure sodium lamp). UV - visible absorption and TOC measurement were employed to disclose details of decolorization and mineralization. The presence of gold ion in TiO2 greatly enhanced their photo - activity. The optimum molar content of gold ion doping was 0.5%. Investigation of crystal structure, chemical components, optical absorption properties, photoluminescence emission spectra and photo - voltage properties disclosed the mechanism of gold ion doping. UV - visible absorption spectra showed that the optical absorption increased in the visible region. Owing to gold impurity energy level, it is possible for gold ion doped TiO2 to be excited by visible light (E < 3.2 eV). Gold impurities also lead to decrease photoluminescence (PL) emission and electron - field - induced surface photo - voltage spectra (EFISPS) and hinder the recombination of electron/hole. The order of EFISPS intensity and PL intensity (from weak to strong) had a good agreement with that of photo - activity (from strong to weak).