An overview on recent developments in synthesis and molecular level structure of visible-light responsive g-C3N4 photocatalyst towards environmental remediation

Abstract

Semiconductor based photocatalysis was adopted by research community as a propitious way to tackle the energy and environmental issues. Among various semiconducting photocatalysts like BiVO4, TiO2, CeO2, BiPO4, g-C3N4, CdS etc., the visible light responsive g-C3N4 photocatalyst is being considered as a very fascinating research topic since the outstanding work carried out by Wang and his co-workers in 2009 on photocatalytic water splitting. This conjugated and metal free semiconductor has drawn extensive attention towards environmental issues since a decade or more due to its high chemical durability, electronic structure and a narrow band gap (2.7 eV). Its structures are based on two building blocks namely s-triazine and tri-s-triazine. The structure based on tri-s-triazine was considered as the most established structure. The investigation of basic structures of tri-s-triazine based g-C3N4 such as geometric, electronic and band structures provides significant information to determine its photoefficiency. In this review, we illustrate a comprehensive study of the recent progress regarding the synthesis protocol of g-C3N4. Its geometric structure, electronic structure and band structure were carefully overviewed. Photocatalytic decomposition of various pollutants over g-C3N4 under irradiation of visible light in aqueous medium and its plausible mechanism was also highlighted. The emerging challenges and future prospective at the prominence of this fascinating research topic have also been depicted in the conclusion.