Enhanced visible-light-driven photocatalytic activity in yellow and black orthorhombic NaTaO3 nanocubes by surface modification and simultaneous N/Ta4+ co-doping

Perovskite-type NaTaO3 as a wide band semiconductor shows good catalytic activity under UV light irradiation. In this work, chemical manipulation methods including surface modification and elemental doping have been adopted to improve the catalytic activity of NaTaO3 nanocubes for visible-light-driven applications. Firstly, a facile hydrothermal route was established to fabricate uniform NaTaO3 nanocubes with orthorhombic structure, which exhibited narrower band gaps than that of cubic NaTaO3. During this syntheses process, glucose could be used as the local structure modifier to generate modified NaTaO3 nanocubes with increased surface defects. Subsequent annealing treatment in NH3 atmosphere yielded anion (N3-) and self- (Ta4+) simultaneously doped products with further enhanced photocatalytic response in the visible region. The dramatic red shifts of the band gap of NaTaO3 into the visible region were associated with both the local crystal structure variation and exotic molecular level of the doping elements. The optimized products, black-coloured NaTaO3-xNy, exhibit desirable band gap down to 2.2 eV and excellent photocatalytic activity for the degradation of organic pollutants under visible light irradiation. More importantly, our approach for preparing Ta4+/N co-doped NaTaO3 provides a good example for the combination of controllable syntheses routes and chemical doping methods to promote traditional wide-band catalysts for visible-light driven applications. (C) 2015 Elsevier Inc. All rights reserved.