Production of visible activity and UV performance enhancement of ZnO photocatalyst via vacuum deoxidation

ZnO photocatalyst with surface oxygen vacancies was obtained via vacuum deoxidation method. The concentration of surface oxygen vacancies could be controlled by tuning the temperature and time in vacuum, which governs the production of visible activity and the enhanced level of photocatalytic activity. The optimum UV photocatalytic activity and photocurrent of vacuum ZnO are almost 1.7 and 2.4 times as high as that of pure ZnO, respectively. Interestingly, the dramatic visible photocatalytic activity and distinct photocurrent both are generated due to the introducing of oxygen vacancies on ZnO surface. The enhancement in performance is attributed to the high separation efficiency of photogeneration electron-hole pairs due to the broadening of the valance band (VB) induced by surface oxygen-vacancies states. The production of visible photoactivity is demonstrated to be the narrow of energy band gap resulting from the rising of VB. (C) 2013 Elsevier B.V. All rights reserved.