Single atoms in environmental catalysis: Breakthroughs in synthesis and application

Due to their outstanding catalytic properties of high stability, high selectivity, and high activity, single-atom catalysts (SACs) have attracted the attention of research teams worldwide. The synthesis and application breakthroughs of single atom in environmental catalysis have been systematically reviewed in this study. With nearly 100 % atomic utilization and easy separation, single-atom catalysts take into account the advantages of homogeneous and heterogeneous catalysts. The results show that the common preparation methods of monatomic catalysts include arc discharge, strong electrostatic adsorption (SEA), flame spray pyrolysis (FSP) and atomic layer deposition (ALD). Common single-atom catalyst supports include graphene, zeolites, and oxides. Common anchoring sites for single-atom catalysts include surface atomic sites, doped heteroatom sites, hole sites, defect sites, metal sites, and curvature sites. In addition, this study also reviewed the application of single-atom catalysts in the field of environmental catalysis, focusing on the breakthroughs of single-atom catalysis in solving volatile organic compounds (VOCs) emission control, activating peroxymonosulfate (PMS) to degrade pollutants, and green energy conversion (GNC). The results show that coordination number and orbital interactions play an important role in the catalytic mechanism of single-atom catalysts. This review indicates that single-atom catalysts have broad application prospects in areas such as air pollution, water pollution, and energy conversion. In addition, the cost, lifespan, loading rate, and secondary pollution of single-atom catalysts will still be issues that require special attention in the future.