Graphene coupled TiO2 photocatalysts for environmental applications: A review

Nanostructured photocatalysts have always offered opportunities to solve issues concerned with the environmental challenges caused by rapid urbanization and industrialization. These materials, due to their tunable physicochemical characteristics, are capable of providing a clean and sustainable ecosystem to humanity. One of the current thriving research focuses of visible-light-driven photocatalysts is on the nanocomposites of titanium dioxide (TiO2) with carbon nanostructures, especially graphene. Coupling TiO2 with graphene has proven more active by photocatalysis than TiO2 alone. It is generally considered that graphene sheets act as an electron acceptor facilitating the transfer and separation of photo-generated electrons during TiO2 excitation, thereby reducing electron-hole recombination. This study briefly reviews the fundamental mechanism and interfacial charge-transfer dynamics in TiO2/graphene nanocomposites. Design strategies of various graphene-based hybrids are highlighted along with some specialized synthetic routes adopted to attain preferred properties. Importantly, the enhancing interfacial charge transfer of photogenerated eCB through the graphene layers by morphology orientation of TiO2, predominated exposure of their high energy crystal facets, defect engineering, enhancing catalytic sites in graphene, constructing dedicated architectures, tuning the nanomaterial dimensionality at the interface, and employing the synergism adopted through various modifications, are systematically compiled. Portraying the significance of these photocatalytic hybrids in environmental remediation, important applications including air and water purification, self-cleaning surfaces, H-2 production, and CO2 reduction to desired fuels, are addressed. (C) 2021 The Authors. Published by Elsevier Ltd.

Automated summary

Nanostructured photocatalysts, such as titanium dioxide (TiO2) composites with graphene, hold promise for addressing environmental challenges by providing a clean and sustainable ecosystem to humanity. The coupling of TiO2 with graphene has shown to be more active in photocatalysis, with graphene sheets facilitating the transfer and separation of photo-generated electrons during TiO2 excitation, ultimately reducing electron-hole recombination. Various design strategies and synthetic routes have been highlighted to enhance the interfacial charge transfer dynamics in TiO2/graphene nanocomposites for environmental remediation applications.