Oxygen defect rich Bi2S3/SnS2/Bi-self doped Bi2W2O9 multijunction photocatalyst for enhanced degradation of methyl parathion and H2 evolution

In this study, a facile in situ co-assembly technique is developed for one pot fabrication of Bi2S3/SnS2/Bi2W2O9 multijunction photocatalyst. Initially, Aurivillius phase Bi2W2O9 with nanoplate morphology is prepared by combustion synthesis route. The hydrothermal co-deposition of SnS2 and Bi2S3 phase led to the formation of the ternary composite photocatalyst. During hydrothermal treatment, substantial microstructural reorganization of the BWO phase occurred resulting in exfoliation of the nanoplates to high aspect ratio nanosheets followed by substitution of Bi5+ ions in the [W2O7]2- bilayer of the BWO structure. The Bi-self doping phenomena also resulted in creation of oxygen vacancy in the BWO lattice. Morphological investigations revealed intimate interfacial contact among hexagonal SnS2 nanoplates, Bi2S3 nanorods and Bi-doped Bi2W2O9 nanosheets. The oxygen vacancy (OV) and Bi self-doping endow improved photoelectrochemical properties and enhanced photocatalytic activity towards methyl parathion photodegradation (kapp = 0.013 min−1) and hydrogen evolution (0.92 mmolg-1h−1). The optimal BS15BWO photocatalyst exhibited nearly 13 and 32 times higher photocatalytic activity for methyl parathion photodegradation and H2 evolution reaction in comparison to the pure components. The robust generation of •OH and •O2− radicals and improved charge channelization through a type-I conjugated dual S-scheme electron migration mechanism accounted for the improved photocatalytic activity of the ternary composite.