Advances in photoactive g-C3N5 derived Z-and S-scheme heterojunctions for energy and environmental catalysis
Vatika Soni, Tarannum Tarannum, Pardeep Singh, Quyet Van Le, Van‐Huy Nguyen, Aftab Aslam Parwaz Khan, Chaudhery Mustansar Hussain, Pankaj Raizada
Abstract
Graphitic carbon nitride derivatives have received wide attention as sustainable, metal-free photoactive catalyst. Among other derivatives, N-rich-g-C 3 N 4 i.e. g-C 3 N 5 has newly emerged as a next-generation catalytic semiconductor with improved electronic and structural characteristics than g-C 3 N 4 . The higher N-content as well as exclusive motifs like: triazole, triazine, and heptazine units, give g-C 3 N 5 with a lower bandgap, extended π-conjugation, boosted charge transfer, and stronger absorption of visible-light. Numerous N-rich precursors and synthesis methods allow the formation of frameworks containing triazole linkages, triazine combinations, and azo bridges, providing flexible routes for the modifying its structure. A thorough discussion on fabrication and characterization is highlighted, focussing on their influence on optical and electronic efficacy. Special emphasis is given to Z- and S-scheme heterojunctions, which create internal electric fields and promising band bending, thereby helping directional charge migration while conserving high oxidation and reduction potential. These heterostructures enhance visible-light utilization and catalytic stability in both energy and environmental applications. Furthermore, functionalization, porosity engineering, and defect regulation have extended the reactivity of g-C 3 N 5 , representing its versatility in complex catalytic systems. This review highlights the fundamental properties, structural engineering approaches, and emerging applications of g-C 3 N 5 , while also addressing the challenges that remain for advancing its role in sustainable photocatalysis. • g-C 3 N 5 outperforms g-C 3 N 4 with higher N-content and improved properties. • Exclusive triazole, triazine, and heptazine units’ changes bandgap and absorption. • Various synthesis routes allow structure alteration and defects regulation. • g-C 3 N 5 -based Z/S-scheme heterojunctions improve charge transfer and stability. • Mechanistic insights into energy and environmental applications are widely discussed.