Band gap tuning of Na1-xLaxTa1-xCoxO3 solid solutions for visible light photocatalysis

Monophase solid solutions Na1-xLaxTa1-xCoxO3 (x=0-0.25) were prepared with conventional solid state reactions method. The band gaps of the solid solutions can be tuned to effectively absorb visible light, with varying x value. The Na0.9La0.1Ta0.9Co0.1O3 photocatalyst exhibited the highest performance of H-2 evolution (4.34 mu mol/h) under visible light irradiation (lambda>420 nm), whereas no H-2 evolution is observed for NaTaO3 under the same conditions. The first principles calculation using generalized gradient approximation revealed that the band gap alteration and the photocatalytic activities of Na1-xLaxTa1-xCoxO3 are mainly due to the hybridization of Co 3d and O 2p orbitals. (C) 2007 American Institute of Physics.