Energy structure and photocatalytic activity for water splitting of Sr2(Ta1-xNbx)2O7 solid solution

Photophysical and photocatalytic properties of Sr-2(Ta1-XNTbX)(2)O-7 with layered perovskite structure were studied to explore the possibility of energy structure control by making a solid solution. The band gap of Sr-2(Ta1-XNbX)(2)O-7 was decreased as the ratio of niobium to tantalum was increased. The Sr-2(Ta1-XNbX)(2)O-7 solid solution photocatalysts loaded with NiO co-catalysts decomposed water into H, and O-2 in a stoichiometric ratio. A NiO/Sr(2)TA(2)O(7) photocatalyst showed the highest activity. The photocatalytic activity was drastically decreased by substitution of a small amount of niobium (X = 0.05) for tantalum. However, a Sri(Ta0.75Nb0.25)(2)O-7 photocatalyst showed a relatively high activity among the solid solutions of Sr-2(Ta1-XNbX)(2)O-7 (0 < X < 1). The activities Of Sr-2(Ta1-XNbX)(2)O-7 solid solution photocatalysts depended on the conduction band level and the efficiency of non-radiative recombination between photogenerated electron-hole pairs. (C) 2001 Elsevier Science B.V. All rights reserved.