Photocatalytic carbon dioxide reduction: Exploring the role of ultrathin 2D graphitic carbon nitride (g-C₃N₄)

Photocatalytic CO₂ reduction is the key strategic factor to mitigate the detrimental consequences arising from greenhouse gases (predominantly anthropogenic CO₂). Products (CH₄, C₂H₆, CH₃OH, C₂H₅OH, etc.,) that are derived from the reduction of CO₂ could be promising alternatives to petro-derived fuel/chemicals. Even though a great deal of efforts has been devoted to increase the conversion efficiency of CO₂, the technical readiness level (TRL) has not yet been fully matured. This review emphasizes on the emerging functional material ultrathin two-dimensional (2D) nanosheet graphitic carbon nitride (g-C₃N₄) for the reduction of CO₂ into value-added products. Physico-chemical properties of 2D-cabon nitride (sizeable surface-to-volume ratio, supplementary active sites onto the surface, shorter diffusion length, bandgap tuning, atomic thickness, and bulk to surface charge transportation) governing the photocatalytic activity are discussed. This review provides recent advances in 2D-carbon nitride photocatalysts to highlight the ongoing challenges and new strategies to optimize their functionality for improved selectivity for CO₂ conversion.