Dual-facet engineering of surface carboxyl functionalization and interlayer potassium ions regulation in carbon nitride for enhanced CO₂ photoreduction

Simultaneous optimization of surface and interlayer characteristics of graphite-phase carbon nitride (g-C₃N₄) is crucial for enhanced photogenerated-carrier separation efficiency. Integration of distinct strategies with specific merits for constructing efficacious charge carrier transport pathways from bulk to surface faces challenges. Herein, we proposed a novel carboxyl functional group and potassium (K) ions co-modified g-C₃N₄ for steering dynamic charge transfer processes. Specifically, carboxyl functional groups were grafted to the surface to substantially improve charge carrier dynamics through the driving force induced by its electron-withdrawing effects. Concurrently, K ions were inserted into the interlayers of g-C₃N₄ to facilitate interlayer carrier transport by bridging adjacent layers. Such a bi-functional photocatalyst achieves 8.68-fold increase in CO yield compared wtih the pristine g-C₃N₄ without any cocatalyst or sacrificial agent. This work provides a profound discernment into the directional transport of charge carriers within the surface and interlayers, and presents a promising approach for rational design of photocatalysts with remarkably efficient solar energy conversion.