Homogenously carbon-doped polymeric carbon nitride porous nanosheets with improved exciton dynamics for enhanced...

Polymeric carbon nitride (CN), a metal-free semiconductor responsive to visible light, has garnered considerable interest for photocatalytic hydrogen evolution (PHE). However, its practical efficiency is limited by poor exciton dissociation and low charge-carrier mobility. To overcome these challenges, we developed homogenously carbon-doped CN porous nanosheets (ACCN) using a deep eutectic solvent-induced in-situ doping strategy. Temperature-dependent photoluminescence spectroscopy and density functional theory (DFT) calculations revealed that the incorporation of additional sp²‑carbon atoms into heptazine units induces uneven electron distribution, thereby reducing exciton binding energy and enhancing exciton dissociation. The improved exciton dynamics were further validated by femtosecond transient absorption spectroscopy. Additionally, the porous nanosheet structure increases the density of surface-active sites and facilitates charge transport. As a result, ACCN achieves a tenfold enhancement in PHE activity under visible light compared with pristine CN. Remarkably, a high hydrogen evolution rate of 13.7 mmol g^-1 h^-1 was sustained over 24 h under simulated sunlight (AM 1.5G) at room temperature without significant degradation. This study presents a facile and effective strategy for engineering CN-based materials with enhanced excitonic properties to enable efficient photocatalytic applications.