Incorporation of benzene rings and nickel atoms into g-C3N4 framework with enhanced spatial charge transfer for efficient photocatalysis

Graphitic carbon nitride (g-C 3 N 4 , CN) has garnered significant attention in the field of photocatalytic hydrogen production due to its unique electronic structure and ease of functional modification. However, the photocatalytic performance of CN is substantially limited by sluggish charge carrier dynamics and a scarcity of active centers. Herein, a novel photocatalyst is designed by modifying CN with nickel atoms and introducing benzene rings (Ni-BCN) onto its structure. The optimized Ni-BCN photocatalyst demonstrates remarkable photocatalytic activity without Pt as a co-catalyst. The hydrogen evolution rate reaches 1844.3 μmol g -1 h −1 , which is nearly 49.7 times higher than that of pristine CN. This significant enhancement is primarily attributed to the fact that the introduction of benzene rings into the CN framework provides driving force for improving charge separation within the in-plane, optimizing the energy band through an extended π-conjugated structure to enhance light absorption, and forming van der Waals heterojunctions that facilitates interlayer electron flow. Additionally, nickel atoms as active sites accelerate proton adsorption and reduce the free energy barriers of hydrogen evolution. This work purposefully optimizes the properties of CN by regulating its molecular structure, thereby fully leveraging these advantages in photocatalytic hydrogen evolution.