Photocatalytic applications of graphene based semiconductor composites: A review

Abstract

Photocatalysis has proven its virtue as an emerging area of research since its discovery. In the primary stages of research, semiconductors like TiO2, ZnO, PtO2 etc. have been used to carry out various photocatalytic processes such as hydrogen energy generation, water treatment, conversion of CO2 to energy fuels, microbial disinfection and organic transformations. Though these semiconductors had a great potential in them, high rate of recombination of charge carriers has allegedly been reported to minimize their expected photocatalytic yield. In the recent era graphene has attracted so many eyes owing to its magical properties like ultrafast electron transport, higher specific surface area, higher rate of adsorption, high mechanical strength, chemical and thermal stability. Introduction of graphene to couple with semiconductor photocatalysts helped in increasing the efficiency of pristine semiconductors to many folds. Being a two-dimensional nano material with a greater number of trapping site, it holds the semiconductors very strongly. The π-conjugated electronic structure makes it an ultimate electron acceptor. Graphene transfers the accepted electrons very quickly and easily because of its zero-bandgap structure. By virtue of such fascinating properties, it separates the photogenerated electrons from the semiconductor to reduce the recombination of charge carriers. In this work, we have focussed on synthesis strategies of grapheme based semiconductor photocatalysts and reviewed briefly their diversified photocatalytic applications.