Catalytic conversion of CO2 to chemicals and fuels: the collective thermocatalytic/photocatalytic/electrocatalytic approach with graphitic carbon nitride

Abstract

Rapid industrial development and the excessive use of fossil fuels have produced a significantly large volume of CO₂ in the atmosphere. The efficient conversion of CO₂ to useful chemicals and fuels is an important step towards reducing the concentration of CO₂. To overcome the thermodynamic and kinetic barriers involved in CO₂ activation and conversion, an effective heterogeneous catalyst and a suitable form of energy, such as thermal, photochemical, and electrochemical, are necessary. Considering a wide variety of catalytic materials for CO₂ conversion using all forms of energy resources discussed above, earth-abundant carbon materials have exhibited the capability to catalyze the thermal, photo-assisted, and electrochemically mediated conversion of CO₂. Among carbon-based materials, graphitic carbon nitride (g-C₃N₄) is an inexpensive and sustainable catalyst that can be effectively used for CO₂ conversion. The chemical reactivity and optoelectronic properties of g-C₃N₄ can be finely tailored for its use as a conventional catalyst or photocatalyst or photoelectrocatalyst. This article aims to summarize the synthetic strategies to prepare various types of g-C₃N₄ materials as conventional catalysts/photocatalysts/electrocatalysts for the improved conversion of CO₂ to chemicals and fuels. This article reviews the utilization of CO₂ as a feedstock for chemical and fuel synthesis via insertion, carboxylation, and reduction reactions. Further, an in-depth understanding of the catalytic mechanism of various reactions discussed in this article will help in the design of a new generation of heterogeneous catalysts for CO₂ conversion. Special emphasis is placed on the various parameters influencing the photocatalytic and electrocatalytic CO₂ reduction. Finally, the underlying challenges and outlook for the future development of catalysts for CO₂ conversion to specialty chemicals and fuels are discussed.