Sustainable Synthesis of Graphene Oxide from Waste Sources: A Comprehensive Review of Methods and Applications

Graphene-based materials have gained significant attention due to their unique mechanical, chemical, thermal, and optical properties. Among these, Graphene oxide (GO) is one of the promising materials extensively studied. Unlike other graphene derivatives, GO is chemically modified with diverse oxygenated functional groups, rendering it more hydrophilic. It serves as a precursor for graphene synthesis. Notably, recent researchers have focused on synthesising GO using alternative low-cost carbon-rich materials such as coconut shells, sugarcane bagasse, tea, pine leaves and scrap tyres instead of graphite. These non-conventional carbon sources decrease the demand for costly, non-renewable graphite, increase reliability, and offer an eco-friendly approach to waste management. This comprehensive review aims to explore accessible methods for synthesising graphene oxide and highlight various alternative feedstocks utilising agricultural, industrial, and plastic waste as precursors. Furthermore, a comparative assessment of various production methods and their performance in different applications is outlined to provide insights for the commercialisation of GO in future applications.