Tailored sunlight driven nano-photocatalyst: bismuth iron tungstate (BiFeWO6)

Abstract

The challenge in employing tungstates for photocatalytic water splitting is to position their conduction band offset with that of the redox potential. As envisaged in Bi₂WO₆, conduction band minimum (CBM) is shifted, but the bandgap energy value is around 3.1 eV. Thus, the strategy of shifting the CBM and reducing the bandgap energy is demonstrated to tailor a novel sunlight driven visible light photocatalyst. Accordingly, BiFeWO₆ nanoparticles (BFWO NPs) have been synthesized by a facile co-precipitation method. The X-ray diffraction results confirmed that the structure of BFWO is a defect pyrochlore. The FESEM images revealed spherical morphology, and the particle size range from 15 nm to 30 nm was observed from HRTEM images. The optical bandgap energy of the synthesized BFWO NPs was estimated to be 2.35 eV using the UV-DRS spectrum, and CBM is positioned with respect to its electronegativity. The photocatalytic activity of the synthesized BFWO NPs was investigated on the degradation of methylene blue under direct irradiation of sunlight, and the observed efficiency is explained with the crystal field theory.