Photocatalytic hydrogen production from aqueous methanol solutions under visible light over Na(Bi xTa 1− x)O 3 solid-solution

Abstract

A series of equivalent substitution solid-solution Na(Bi x Ta 1− x )O 3 ( x = 0–0.10) was prepared by a simple hydrothermal method using Ta 2O 5 and NaBiO 3 as precursors. The Na(Bi 0.08Ta 0.92)O 3 photocatalyst exhibited the highest performance of H 2 evolution (59.48 μmol h −1 g −1) under visible-light irradiation ( λ > 400 nm) without co-catalyst, whereas no H 2 evolution is observed for NaTaO 3 under the same conditions. The UV-Vis spectra indicate that the Na(Bi 0.08Ta 0.92)O 3 powders can absorb not only ultraviolet light like pure NaTaO 3 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(Bi x Ta 1− x )O 3 catalysts are attributed to the band transition from the O2p to the Bi2s + 2p + Ta5d hybrid orbital.