Enhanced Photocatalytic CO₂ Reduction by Amine Functionalization of Graphitic Carbon Nitride

Graphitic carbon nitride (g‐CN) is a promising photocatalyst for solar fuel generation, but its charge carrier mobility, charge recombination, and CO₂ reduction/H₂ evolution efficacy and selectivity are a strong function of the synthesis and postsynthesis techniques employed. Protonation and phosphorous doping of g‐CN yield promise visible light activities, promoting enhanced CO₂ reduction and hydrogen evolution. However, the amine‐functionalized surface chemistry of g‐CN gains little attention in open literature. Herein, g‐CN and phosphorus‐doped g‐CN are synthesized via facile one‐pot pyrolysis and subjected to protonation postsynthesis to quantify the influence of common strategies on surface amine content and photocatalyst activity for H₂ evolution and CO₂ reduction. Material characterization confirms the exfoliation of the photocatalyst and change in the amine functionalization of the surface. The amorphous phosphorus‐doped g‐CN material exhibits a high number of surface amine groups, increasing the adsorption prior to reduction and enhancing selectivity for CO₂ reduction.