New-Generation Oxide Semiconductors for Solar Energy Conversion and Environmental Remediation

Two oxide semiconductors, namely, bismuth vanadate (BiVO4) and silver bismuth tungstate (AgBiW2O8) were prepared by solution combustion synthesis and their attributes as photocatalysts were comparatively evaluated. A key conclusion of this study is that the optical characteristics alone provide only a partial glimpse into the applicability of a given semiconductor for solar energy conversion and environmental remediation. Thus while the optical bandgap of BiVO4 is lower than AgBiW2O8 (and thus is able to harness a greater portion of the solar spectrum), its photocatalytic activity for the degradation of a dye is inferior. This finding underlines the fact that other characteristics of the semiconductor (band-edge alignment, surface quality etc) also play as critical a role as the optical properties.