Insight into the properties, morphologies and photocatalytic applications of S-scheme Bi2WO6

The excellent structural, electrical and optical properties of Bi2WO6 (BWO) retain its potential as photocatalytic material for productive environmental and energy conversion applications. The n-type semiconducting behaviour and bandgap of 2.6 – 2.8 eV enable BWO photoactivity operational under the visible range. The orthorhombic structure drafted by [Bi2O2]2+ layers joined with corner allocated [WO4]2- layers where W is a six-fold coordinated central atom surrounded by an oxygen octahedron. Such arrangement provides an eccentric sandwiched structure to BWO and assists in inducing a built-in electric field between the layers favourable for their high charge separation ability during photocatalysis. Further, non-toxicity, facile fabrication, and diverse morphological variation with the optimized surface area are certain perceptible features of BWO. However, lowering the recombination process and refining the quantum efficiency of BWO is still challenging. This review explores photo-efficiency enhancement via diverse morphological variations, surface engineering, surface defects, doping/co-doping, Z-scheme and S-scheme heterojunction formation. The photocatalytic efficiency is a prospect by BWO application in photodegradation, CO2 photoreduction, H2 production and photocatalytic N2 fixation. Moreover, the challenges, opinions, and opportunities are provided to further insight into developing new photocatalytic materials.