A review on Cu single-atom-modified g-C3N4 for applications in photocatalytic energy conversion and environmental photocatalysis

Abstract

Graphitic carbon nitride (g-C3N4) is a graphene-like polymeric semiconductor formed by sp2 hybridization of carbon and nitrogen atoms. Its unique electronic structure (bandgap of approximately 2.7 eV) and visible-light response characteristics make it significant for photocatalytic applications. However, pristine g-C3N4 typically suffers from insufficient surface-active centers, rapid photogenerated charge recombination, and low interfacial reaction efficiency, severely limiting its photocatalytic performance. To overcome these limitations, anchoring metal single atoms on g-C3N4 has emerged as an effective strategy to enhance photogenerated charge transfer rates and provide additional surface-active sites. Among various metal single atoms, Cu single atoms demonstrate unique advantages due to their high catalytic activity, tunable electronic states (Cu0/Cu+/Cu2+), and economic viability. Here, this review systematically presents the preparation and characterization of Cu single-atom-modified g-C3N4 (Cu SAM-g-C3N4) photocatalysts, as well as their wide applications in energy conversion (H2 production, CO2 reduction, NH3 production, organic synthesis), environmental photocatalysis (degradation of organic pollutants, sterilization), and other reactions. This work provides valuable guidance for the application and development of Cu SAM-g-C3N4 photocatalysts in energy and environmental fields.