The progress of g-C3N4 in photocatalytic H2 evolution: From fabrication to modification

Polymeric semiconductor, Graphitic Carbon Nitride (g-C3N4), has emerged as one of the desired materials in photocatalytic hydrogen evolution (PHE) due to its visible-light activity, facile accessibility, low-cost, chemical stability, as well as the unique layered structure. However, pure g-C3N4 photocatalyst suffers from limited photocatalytic performance due to the low efficiency of charge carrier separation and serious charge recombination. Researches over the past few decades have shown that the photocatalytic active of g-C3N4 can be easily affected by many factors including spatial morphology, electronic structure, as well as the interaction between g-C3N4 and other materials. This review gives a comprehensive introduction over the basic properties and the development of g-C3N4 in PHE. A brief history and the basic properties are firstly introduced. After then, this review introduces the fabrication and the limits of g-C3N4 in PHE, followed by the rational methods in improving the photocatalytic active of g-C3N4 including the self-modification strategies (e.g., molecular structure regulation, defect engineering and microstructure manipulation) and the exogenous modification strategies (e.g., the deposition of co-catalyst and the construction of g-C3N4 based heterostructure). Lastly, this review discusses the major challenges and opportunities of g-C3N4 in photocatalytic field. It is believed that this review is benefit for proposing more effective solutions in developing high active g-C3N4 photocatalysts based on a comprehensive understanding of g-C3N4 material.