VOCs诱导TiO_2光生载流子的分离

Dffects of VOCs on the separation of photogenerated charge carriers on anatase TiO_2

气体分子直接影响光生载流子的分离行为,进而影响光催化降解挥发性有机物(volatile organic compounds,VOCs)的效率.本研究以甲苯、环己烷和甲基环己烷为VOCs代表,采用气氛表面光电压谱仪研究VOCs和氧气-VOCs气氛条件下锐钛矿TiO_2光生载流子的传输行为.实验结果表明:VOCs可增强锐钛矿TiO_2可见光区域光生载流子的分离,其中甲苯的增强作用显著强于环己烷和甲基环己烷.3种VOCs对带带跃迁光生载流子分离效率的影响均不显著,但与氧气共存则均能显著提高光生载流子的分离效率,提高的趋势为:甲苯>甲基环己烷>环己烷.

Gas molecules exert a direct influence on the separation of photogenerated charge carriers,which affects the photocatalytic degradation efficiency of volatile organic compounds. In this study,toluene,cyclohexane,and methylcyclohexane were selected as representative VOCs. The charge separation of anatase TiO2 in VOCs atmosphere or VOCs-oxygen atmosphere was measured via atmosphere-surface-photovoltage-spectroscopy. The results showed VOCs enhanced the separation of photogenerated charge carriers in the visible region. The enhancement of toluene was significantly greater than that of cyclohexane and methylcyclohexane. Further more,three VOCs had little effect on the photogenerated charge carriers from band-to-band transition. VOCs in the presence of oxygen obviously enhanced the separation of photogenerated charge carriers from band to band transition with the order of toluene〉 methylcyclohexane〉 cyclohexane.