Langmuir. 2018 Jun 19;34(24):7034-7041. doi: 10.1021/acs.langmuir.8b01011. Epub 2018 Jun 6.
Understanding the mechanism by which oxygen adsorption influences the separation behavior of charge carriers is important in photocatalytic removal of air pollutants. In this study, we performed steady-state surface photovoltage and surface photocurrent spectroscopy combined with an atmosphere control system to determine the effect of oxygen on the charge separation behavior at the surface of anatase TiO nanoparticles at ambient temperature. Results showed that photogenerated electrons were movable in N atmosphere but were localized in O atmosphere. O obviously enhanced the stabilization of the localized photogenerated electrons when the surface defects of TiO were fully occupied by adsorbed O. Moreover, O adsorption increased the energy demand for exciting electrons from the valence band to localized surface defect states and reduced the density of band tail states. These findings suggest us that the effect of gaseous species on the mobility and stability of charge carriers should be considered to understand the photocatalytic degradation of air pollutants.
了解氧吸附如何影响载流子的分离行为对于光催化去除空气污染物至关重要。在本研究中，我们采用稳态表面光电压和表面光电流光谱学结合气氛控制系统，在环境温度下研究了氧对锐钛矿 TiO 纳米粒子表面载流子分离行为的影响。结果表明，在 N 气氛中，光生电子是可移动的，但在 O 气氛中，光生电子是局域的。当 TiO 的表面缺陷被吸附的 O 完全占据时，O 明显增强了局域光生电子的稳定性。此外，O 吸附增加了从价带激发电子到局域表面缺陷态所需的能量，并降低了带尾态的密度。这些发现使我们认识到，在理解空气污染物的光催化降解时，应考虑气态物质对载流子迁移率和稳定性的影响。
