Ultra-thin nanosheet assemblies of graphitic carbon nitride for enhanced photocatalytic CO2 reduction

Abstract

A two-dimensional layered polymeric photocatalyst, graphitic carbon nitride (g-C₃N₄), is becoming the rising star in the field of solar-to-fuel conversion. However, the performance of commonly prepared g-C₃N₄ is usually very weak because of the high recombination rate of photogenerated charge carriers and a small amount of surface active sites. Here we demonstrate simultaneous texture modification and surface functionalization of g-C₃N₄via a stepwise NH₃-mediated thermal exfoliation approach. The resulting g-C₃N₄ photocatalyst possesses a hierarchical structure obtained by the assembly of amine-functionalized ultrathin nanosheets and thus exhibits remarkably enhanced light harvesting, a high redox ability of charge carriers, increased CO₂ adsorption and a larger amount of surface active sites, as well as improved charge carrier transfer and separation. Therefore the aforementioned hierarchical g-C₃N₄ consisting of amine-functionalized ultra-thin nanosheets shows much better performance for photocatalytic CO₂ reduction than unmodified conventional g-C₃N₄ photocatalysts.