Band-engineered CaTiO3 nanowires for visible light photocatalysis

We have theoretically investigated the structural, electronic, and optical properties of the perovskite CaTiO3 nanowires for visible light photocatalytic applications using pseudopotential density-functional theory calculations. The electronic structure calculations show that the band gap is greatly modified in the CaTiO3 nanowires compared with that of the bulk. For the TiO2-terminated nanowires, the electronic states on the valence band maxima induced by combining oxygen and calcium atoms on the surface lead to a shift in the valence band toward the conduction band without interference from the edge of the conduction band, which reduces the band gap. On the contrary, the electronic states induced by combining oxygen and calcium atoms on the surface of the CaO-terminated nanowires lead to a shift in the conduction band toward the valence band. The calculated optical results indicate that the absorption edge of the nanowires shifts towards the red-light region. These theoretical results suggest that the perovskite CaTiO3 nanowires are promising candidates for visible light photocatalysis such as solar-assisted water splitting reactions. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4794196]