Photocatalytic hydrogen production from aqueous methanol solutions under visible light over Na(BixTa1-x)O-3 solid-solution

A series of equivalent substitution solid-solution Na(BixTa1-x)O-3 (x = 0-0. 10) was prepared by a simple hydrothermal method using Ta2O5 and NaBiO3 as precursors. The Na (Bi0.08Ta0.92)O-3 photocatalyst exhibited the highest performance of H-2 evolution (59.48 mu mol h(-1) g(-1)) under visible-light irradiation (lambda > 400 nm) without co-catalyst, whereas no H-2 evolution is observed for NaTaO3 under the same conditions. The UV-Vis spectra indicate that the Na(Bi0.08Ta0.92)O-3 powders can absorb not only ultraviolet light like pure NaTaO3 powder but also the visible-light spectrum. The absorption edge corresponds to a band gap of 2.88 eV. The results of density functional theory calculation illuminate that the visible-light absorption bands in the Na(BixTa1-x)O-3 catalysts are attributed to the band transition from the O2p to the Bi2s + 2p + Ta5d hybrid orbital. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.