Graphene coupled TiO2 photocatalysts for environmental applications: A review

• Published in: Chemosphere (Oxford) 2021-05, Vol.271, p.129506, Article 129506
• Main Authors: Padmanabhan, Nisha T., Thomas, Nishanth, Louis, Jesna, Mathew, Dhanu Treasa, Ganguly, Priyanka, John, Honey, Pillai, Suresh C.
• Format: Article
• Language: English
• Subjects: 2D materials; Anti-microbial property; CO2 photoreduction; Synthesis; Titania/graphene hybrids; Water purification; Water splitting
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.129506

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 photogenerated 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 e¯CB 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, H2 production, and CO2 reduction to desired fuels, are addressed. [Display omitted] •Interfacial charge transfer mechanism in TiO2/graphene heterojunctions.•Specialized synthetic strategies for enhanced charge dynamics at the interface.•Facet and defect engineering in TiO2, functionalization in graphene, etc.•Photocatalytic degradation of pollutants and antimicrobial disinfection.•Solar fuel generation by photoreduction of H2O and CO2.