Enhanced Photocatalytic Performance for the BiPO4–x Nanorod Induced by Surface Oxygen Vacancy

The BiPO4–x nanorod with surface oxygen vacancy was fabricated via vacuum deoxidation. The concentration and kind of oxygen vacancy could be controlled by tuning the deoxidation temperature and time in vacuum. The photocatalytic activity depended on the concentration and kind of surface oxygen vacancy, and the optimum photocatalytic activity and photocurrent of the BiPO4–x nanorod was about 1.5 and 2.5 times as high as that of pure BiPO4, respectively. Besides, the photocatalytic response wave range of the BiPO4–x nanorod has been expanded to more than 365 nm. The enhancement of photocatalytic activity is attributed to the high separation efficiency of photoinduced electron–hole pairs due to the broadening of the valence band (VB) induced by surface oxygen-vacancy states, and the extending of photoresponse is considered to be the narrowing of energy band gap resulting from the rise of the valence band maximum (VBM).