Photocatalytic CO2 reduction over g-C3N4 based heterostructures: Recent progress and prospects

Photocatalytic reduction of carbon dioxide (CO2) to produce energy fuels is an attractive approach to address the two most sought problems i.e., the reliance on fossil fuels and environmental pollution. Among various available photocatalysts, graphitic carbon nitride (g-C3N4) has been extensively explored for its potential in CO2 reduction considering its intriguing properties, such as a moderate band gap (with high CB potential), excellent stability, unique layered structure, and cost-effectiveness. However, the pristine material exhibits limited photocatalytic reduction activity due to low CO2 adsorption efficacy and quick recombination of charge carriers. Heterostructure fabrication is by far the most efficient method to improve charge carrier separation efficiency. Moreover, heterostructure formation might impart unique characteristics that would enhance the CO2 adsorption and activation efficacy. In this review, the recent progress in the photocatalytic CO2 reduction over g-C3N4 based heterostructures has been summarized, and the design considerations (CO2 adsorption/activation and charge carrier separation) that impact the performance to a great extent, have been analysed critically. An overview of the most frequently implemented synthesis strategies of g-C3N4 based heterostructures has also been reported. In the end, a concise discussion on the challenges and the prospects of g-C3N4 based heterostructures in CO2 reduction is provided.