Emerging Cocatalysts on g-C3N4 for Photocatalytic Hydrogen Evolution

Over the past few decades, graphitic carbon nitride (g-C3N4) has arisen much attention as a promising candidate for photocatalytic hydrogen evolution reaction (HER) owing to its low cost and visible light response ability. However, the unsatisfied HER performance originated from the strong charge recombination of g-C3N4 severely inhibits the further large-scale application of g-C3N4. In this case, the utilization of cocatalysts is a novel frontline in the g-C3N4-based photocatalytic systems due to the positive effects of cocatalysts on supressing charge carrier recombination, reducing the HER overpotential, and improving photocatalytic activity. This review summarizes some recent advances about the high-performance cocatalysts based on g-C3N4 toward HER. Specifically, the functions, design principle, classification, modification strategies of cocatalysts, as well as their intrinsic mechanism for the enhanced photocatalytic HER activity are discussed here. Finally, the pivotal challenges and future developments of cocatalysts in the field of HER are further proposed.