Engineering of g-C3N4-based composites for photocatalytic and electrocatalytic water splitting: Recent progress, challenges and perspective

Photocatalytic and electrocatalytic water splitting are considered as fabulous approaches to produce hydrogen energy for promoting global energy transition. The g-C3N4 exhibits great potential for both photocatalysis and electrocatalysis owing to the unique physiochemical properties like its suitable bandgap, tunable energy band position, outstanding structure stability, high nitrogen concentration, diverse morphologies, etc. But pure g-C3N4 can only attain limited catalytic performance since it cannot satisfy the diversified requirements of the complex reactions, making it essential to develop and construct efficient g-C3N4 based composites. In this review, diversified synthetic strategies of g-C3N4 based composites are listed systematically and the characteristics of each strategy are discussed in detail. The design principles of g-C3N4 based composites towards photocatalytic water splitting are elaborately summarized from the perspective of both half reactions and overall water splitting, which also deeply probe the relationship between structures and performances. And the development of g-C3N4 based composites for electrocatalytic water splitting is comprehensively concluded with g-C3N4 serving as active component and sacrificial precursor. The current challenges and opportunities of g-C3N4 composites for photocatalytic/electrocatalytic water splitting are presented as well. This review will throw light on preparing outstanding g-C3N4 based composites for realizing competent water splitting and other energy-related applications.