Engineering Ternary Atomic-Scale Catalytic Sites to Efficiently Remove Concentrated 4-Chlorophenol

The ability of single-atom catalysts (SSCs) to degrade refractory organic pollutants in peroxymonosulfate (PMS)-based heterogeneous catalysis can be compromised due to less diversity in reactive species and unfavorable affinity with PMS. Herein, the as-prepared ternary atomic-scale site catalyst comprising single-atomic Fe/Ce sites and Fe cluster sites (Fe-Ce-BC-900) could completely remove concentrated 4-chlorophenol (4-CP, 40 mg L^–1) in aqueous solution within 30 min, 1.20–1.35 times more efficient than Fe SSCs or Ce SSCs. The reactive oxygen species (ROSs) could be highly diversified on the ternary atomic-scale sites because of the Janus mechanisms: the production of nonradicals (¹O₂) through PMS oxidation and the generation of radicals (SO₄^•– and •OH) via PMS reduction on the ternary catalytic sites, which accounted for oxidative degradation of concentrated 4-CP. Density functional theory (DFT) calculations indicated that the ternary catalytic sites enhanced the uneven charge distribution and down-regulated the d-band center of Fe-Ce-BC-900 as compared to Fe-BC-900 and Ce-BC-900 catalysts, thereby optimizing the adsorption energy of PMS molecules and promoting electron transfer between metal sites and adjacent oxygen atoms. This study provides valuable insights into the configuration of multicatalytic sites for detoxification of organic-contaminants-polluted wastewater.