Advances of carbon nitride based atomically dispersed catalysts from single-atom to dual-atom in advanced oxidation process applications

Single-atom catalysts are an essential research object in environmental catalysis because of their unique coordination environment, high utilization rate, high activity and selectivity. The dual-atom catalysts have two sets of atomic centers. The atomically dispersed catalysts (ADCs) from single-atom to dual-atom can bridge the gap between heterogeneous and homogeneous catalysts. The key to the ADCs is forming a stable metal single-atomic site between the catalyst and the support. Graphite carbon nitride has the advantages of chemical stability, structural regulation and visible light absorption. It is one of the most promising two-dimensional materials for stabilizing isolated metal atoms. As an advanced heterogeneous catalyst, graphitic carbon nitride (g-C3N4) based ADCs have great potential in applying advanced oxidation processes (AOPs) to solve environmental problems. However, the research progress of g-C3N4 based ADCs in AOPs needs to be summarized more comprehensively. In this paper, the preparation, catalytic mechanism, stability analysis and environmental application of these materials are reviewed systematically. Finally, the research progress of g-C3N4 based ADCs and the prospects and challenges of this new field prospect are summarized.