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

• Fe incorporated visible light active pyrochlore photocatalyst is synthesized.
• UV–vis driven H2 generation demonstrated using Fe-Bi2Ti2O7 in methanol–water.
• Fe concentration dependent red shift up to 200 nm in visible light absorbance.
• 1 wt% Fe shows 75% higher H2 yield compared to Fe-free Bi2Ti2O7.
• Activity increase with 1 wt% Fe is attributed to a 12.5% reduction in bandgap.

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 100–200 nm depending on Fe doping, and a corresponding increase in photocatalytic activity is noted. Replacing 1 mol% 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.

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