Recent progress on the development of g-C3N4 based composite material and their photocatalytic application of CO2 reductions

Photocatalytic CO2 reduction into valuable hydrocarbons like CH4, CH3OH, C2H5OH, HCOOH, and CO can tackle the problems of fossil fuel shortage and global warming immediately, however, semiconductor photocatalysts have been compensated with huge concentrations in the current years. Because of their small specific surface area and insufficient ability to adsorb CO2, several typical semiconductor samples do not perform as effectively as is required for realistic applications. Consequently, the measurement of catalysts with high CO2 uptake is important in the field of CO2 photoreduction. Graphite carbon nitride (g-C3N4) has materialized as a wunderkind in this area for its plentiful benefits. g-C3N4 with the characteristics of being non-hazardous, highly stable, and inexpensive, shows tremendous visible light absorption features (Eg= 2.7 eV) and for that reason mesmerized widespread concentration in the field of photocatalysis. The photocatalytic efficiency of pure g-C3N4 is low due to quick recombination of photogenerated electron/hole pairs, a low surface area, and insufficient visible light absorption. Its distinct band structure provides a promising approach to enhancing the charge separation, increasing the surface area, and enhancing light absorption when coupled with a large bandgap semiconductor to form a heterojunction composite. For this, g-C3N4 as a potent photocatalyst and a variety of synthesis techniques have been highlighted. Unlike other reviews that have been published, we discuss here the most recent developments in the design of heterostructures based on g-C3N4 for studying photoactivity for CO2 reduction. The g-C3N4 based heterostructures have been classified as semiconductor-supported g-C3N4 based heterostructures, graphene oxide (GO) supported g-C3N4 based heterostructures, non-metal or transition metal supported g-C3N4 based heterostructures, metal-organic frameworks supported g-C3N4-based heterostructures. Besides, the challenges and prospective views of the modified g-C3N4 based heterostructure for CO2 photoconversion were discussed. This review will encourage rigorous investigation into the coherent design and progress of more creative g-C3N4 based heterostructures, which are an environmentally friendly and sustainable method of consuming CO2.