Graphene–Based Photocatalysts

Graphene is a single layer of graphite with a unique two-dimensional structure with high conductivity, superior electron mobility, absorptivity, and specific surface area. The extraordinary mechanical, thermal, and electrical properties of graphene are due to long-range π conjugation. Due to these properties, graphene can be used in nanosystems and nano- devices. The photocatalytic efficiency of composites (semiconductor-based metal oxides and graphene-based photocatalysts) can be improved under visible light. Graphene behaves as an electron acceptor in these types of composite photocatalysts. Different types of graphene-based composites (graphene (G)-semiconductor, graphene oxide (GO)-semiconductor, and reduced graphene oxide (RGO)-semiconductor, where the semiconductor is TiO2, ZnO, CdS, Zn2SnO4, etc.) can be prepared through simple mixing and/or sonication, sol-gel process, liquid-phase, hydrothermal, and solvothermal methods. This chapter includes the most recent advances in different applications of graphene-based semiconductor photocatalysts for degrading various contaminants (treatment of waste water) and producing hydrogen (fuel of future) by photosplitting water, and photo-catalytically reducing carbon dioxide to energy-rich synthetic fuels (combating against global warming and energy crisis), etc.