Recent advances in graphitic carbon nitride-supported single-atom catalysts for H₂O₂production

Graphitic carbon nitride (g-C₃N₄) has emerged as a promising support for single-atom catalysts (SACs) in the photocatalytic synthesis of hydrogen peroxide (H₂O₂) due to its visible-light-responsive properties and periodic nitrogen coordination sites to offer distinct advantages for stabilizing metal single atoms. In this paper, the latest progress in the photocatalytic synthesis of H₂O₂ using g-C₃N₄-supported SACs is systematically summarized. Firstly, based on the introduction of g-C₃N₄-supported SACs, the catalytic mechanism of single-atom active site selectivity is clarified, and the two-electron oxygen reduction reaction path is revealed by regulating the adsorption configuration of oxygen molecules and optimizing the formation path of key intermediate OOH*. Furthermore, different single-atom synthesis methods, such as calcination and deposition, are summarized, and the selection and optimization of reaction conditions are analyzed for the commonly used calcination process. Meanwhile, the application of advanced characterization techniques such as high-resolution transmission electron microscopy (HRTEM) and X-ray absorption spectroscopy (XAS) in the detection of single-atom dispersion and local coordination environment are comprehensively reviewed. In addition, from the two dimensions of single-atom type selection and carrier regulation, the design optimization strategy of SACs based on g-C₃N₄ in H₂O₂ photocatalytic synthesis is discussed. Finally, based on the latest research progress, the key challenges are analyzed from four aspects: g-C₃N₄, SACs, reaction mechanism and industrialization, and the future perspectives is given, which provided a reference for the follow-up research.