Enhancing the visible light absorbance of Bi2Ti2O7 through Fe-substitution and its effects on photocatalytic hydrogen evolution

Abstract

The visible light-driven, photo-assisted hydrogen generation using a pyrochlore-type photocatalyst (A2B2O7), containing an earth-abundant element for boosting photoactivity, is presented. A wet chemical approach has been used for the synthesis of the pyrochlore photocatalyst. The characterization of the material using surface and optical techniques indicates that Fe can be successfully incorporated into Bi2Ti2O7 (BTO) with varying concentrations. The photocatalytic activity of the material was examined by performing hydrogen generation from a methanol–water mixture under UV–vis illumination in a slurry reactor. The wavelength range of visible light absorbed is improved by 100–200nm depending on Fe doping, and a corresponding increase in photocatalytic activity is noted. Replacing 1mol% of the Bi with Fe in the BTO (referred to below as 1% Fe doped or 1% Fe-BTO) is noted to be optimal in improving photocatalytic hydrogen generation, with more heavily doped samples showing progressively lower improvement.