Nanosized amorphous tantalum oxide: a highly efficient photocatalyst for hydrogen evolution

Abstract

A facile synthetic route for the preparation of highly active tantalum oxide photocatalysts was developed without using any surfactants. The prepared products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectra, thermogravimetric analysis, and Raman, and their activity was evaluated by photocatalytic H2 evolution under UV–Vis light irradiation (320 < λ < 780 nm). To elucidate the photocatalytic activity, the nitrogen adsorption–desorption isotherms experiment, ultraviolet–visible diffuse reflectance spectra, photoluminescence and steady-state surface photo-voltage measurements were performed. The recyclable photocatalytic properties were also conducted to demonstrate its high stability. Notably, the obtained samples prepared by direct evaporation are amorphous and own a large specific surface area, and furthermore exhibit a far greater photocatalytic performance than commercial Ta2O5. On the basis of the above experiment results, the enhanced photocatalytic activity of a-Ta x O y could be ascribed to the efficient separation and migration of photo-generated carriers as well as the higher energy of the conduction band minimum. Therefore, the direct evaporation synthesis opens a door to the facile preparation of highly active amorphous photocatalysts.