Graphitic carbon nitride (g–C3N4)–Based Z-scheme photocatalysts: Innovations for energy and environmental applications

Abstract

Unique features of graphitic carbon nitride (g-C₃N₄, gCN) nanocomposites include exceptional chemical stability, ease of manufacturing and modification, spatially segregated photo-induced charge carriers, and feasible redox properties. As a result, they are attracting unusual attention. In particular, the direct Z-scheme heterojunctions (ZSHJ) constructed with gCN exhibit photocatalytic activity and selectivity with applications in the realms of energy and environment. Advances in the synthesis of gCN-based ZSHJ as well as their photocatalytic applications, with emphasis on the decomposition of contaminants in water, production of H₂ and O₂, and conversion of CO₂ to biofuels and biochemical, were highlighted. Insight was provided on the latest developments in gCN ZS photocatalytic materials with the accompanying challenges including the S-scheme photocatalysis. Thus, an in-depth analysis, the limited light absorption range of g-C₃N₄ and its high rate of charge carrier recombination hinder its efficiency. The structural limitations, including low surface area and insufficient porosity, reduce catalytic activity while ensuring the stability of Z-scheme interfaces and preventing back electron transfer remains complex. Moreover, scaling up production and achieving cost-effective synthesis are ongoing hurdles. Addressing these challenges requires innovations in bandgap engineering, composite formation, and morphology control, along with the development of green and scalable synthesis methods.