Construction of dual active sites on diatomic metal (FeCo−N/C-x) catalysts for enhanced Fenton-like catalysis

High metal loading of single-atom catalysts enables excellent catalytic activity, but possibly causes serious aggregation problem. Herein, a series of diatomic FeCo−N/C-x (x represents metal content) were skillfully designed and applied to improve the catalytic activity for peroxymonosulfate (PMS) activation toward degrading organic micropollutants. The unprecedented dual active sites, referring to Fe(N3)−Co(N3) moiety and FeCo alloy, are constructed on the obtained FeCo−N/C-x, thereby exhibiting significantly greater performance toward degrading aqueous phenol (e.g., 0.316 min−1 for FeCo−N/C-3) via PMS activation, compared with those of traditional single-atom Co−N/C (0.011 min−1) and Fe−N/C (0.018 min−1). Combined experimental and theoretical calculations demonstrate the independent functions of dual active sites, in which Fe(N3)−Co(N3) and FeCo alloy can decrease the energy barrier of O−O bond cleaving resulting in the formation of high-valent FeCoO reactive species and singlet oxygen, respectively. This study opens up a new platform toward constructing dual active sites for enhanced Fenton-like catalytic activity.