Engineering oxygen vacancy on rutile TiO2 for efficient electron-hole separation and high solar-driven photocatalytic hydrogen evolution

Abstract

Oxygen vacancy (VO) plays a vital role in semiconductor photocatalysis. Rutile TiO2 nanomaterials with controllable contents of VO (0–2.18%) are fabricated via an in situ solid-state chemical reduction strategy, with color from white to black. The bandgap of the resultant rutile TiO2 is reduced from 3.0 to 2.56 eV, indicating the enhanced visible light absorption. The resultant rutile TiO2 with optimal contents of VO (∼2.07%) exhibits a high solar-driven photocatalytic hydrogen production rate of 734 μmol h−1, which is about four times as high as that of the pristine one (185 μmol h−1). The presence of VO elevates the apparent Fermi level of rutile TiO2 and promotes the efficient electronhole separation obviously, which favor the escape of photogenerated electrons and prolong the life-time (7.6×103 ns) of photogenerated charge carriers, confirmed by scanning Kelvin probe microscopy, surface photovoltage spectroscopy and transient-state fluorescence. VO-mediated efficient photogenerated electron-hole separation strategy may provide new insight for fabricating other high-performance semiconductor oxide photocatalysts.