Bandgap engineering of SrTiO 3 /NaTaO 3 heterojunction for visible light photocatalysis

Hybrid density functional of HSE06 has been adopted to investigate the geometry and electronic properties of SrTiO 3 /NaTaO 3 heterostructures in contrast with the cubic SrTiO 3 and cubic NaTaO 3 . The SrTiO 3 /NaTaO 3 heterostructures with varied monolayers of SrTiO 3 and NaTaO 3 units are constructed, and all the heterojunction systems have the smaller bandgaps as compared with those of pure SrTiO 3 and NaTaO 3 . For the (SrTiO 3 ) m /(NaTaO 3 ) n ( m  +  n  = 10) systems, the bandgap decreases in the order of m  = 1, 2, 3, 4, 5, while the bandgap increases in the order of m  = 5, 6, 7, 8, 9. We also investigate the (SrTiO 3 ) m /(NaTaO 3 ) m systems ( m  = 1, 2, 3, 4, 5, 6, 7), and the calculated results suggest that the (SrTiO 3 ) 6 /(NaTaO 3 ) 6 system has the smallest bandgap of 2.58 eV in our considered systems. This study indicates the development of SrTiO 3 /NaTaO 3 heterojunction is a promising way to improve the photocatalytic activities of SrTiO 3 and NaTaO 3 .