In the search for efficient photocatalysts for water splitting under visible light, the effect of chromium doping in a (100) layered Aurivillius-phase perovskite material, PbBi$_2$Nb$_2$O$_9$, has been studied. The Cr-doped PbBi$_2$Nb$_2$O$_9$ showed three absorption edges: the main edge due to the oxide at 431 nm and shoulders due to the chromium ions at 470 nm and 600 nm, respectively. The Pt/Cr-doped PbBi$_2$Nb$_2$O$_9$ photocatalyst was more active than the undoped PbBi$_2$Nb$_2$O$_9$ for photocatalytic decomposition of water-methanol solution. This is attributed to Cr$^+$ ions having an important role in increasing QYs in the PbBi$_2$Nb$_2$O$_9$.
Keywords: Aurivillius-phase perovskite, Photocatalysts, Visible light, Quantum yield, Band-gap energy