Band gap tuning of Na1-x Lax Ta1-x Cox O3 solid solutions for visible light photocatalysis

Abstract

Monophase solid solutions Na1-x Lax Ta1-x Cox O3 (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 Na0.9 La0.1 Ta0.9 Co0.1 O3 photocatalyst exhibited the highest performance of H2 evolution (4.34 μmolh) under visible light irradiation (λ>420 nm), whereas no H2 evolution is observed for NaTa O3 under the same conditions. The first principles calculation using generalized gradient approximation revealed that the band gap alteration and the photocatalytic activities of Na1-x Lax Ta1-x Cox O3 are mainly due to the hybridization of Co 3d and O 2p orbitals. © 2007 American Institute of Physics.