Peroxymonosulfate activation by a bimetallic catalyst with Fe nanoclusters and Co single-atoms on C3N4 (FeNCCoSA-C3N4) for oxidation of organic pollutants via radical and nonradical pathways

Catalysts with metal nanocluster and single-atom sites have been used extensively to activate persulfate to remove recalcitrant pollutants while the bimetallic catalyst remains limited researches. Here, a bimetallic C3N4 catalyst with relatively high Fe nanocluster and single-atom Co loadings (7.6% and 3.7%, respectively) (FeNCCoSA-C3N4) was successfully synthesized. FeNCCoSA-C3N4 showed a synergistic coefficient of 7.8 relative to Fe-C3N4 and Co-C3N4 for degrading paracetamol, remarkedly outperforming the counterpart monometallic heterogeneous catalysts, metal ions homogeneous catalyst, or previously reported catalysts in terms of peroxymonosulfate (PMS) activation and paracetamol mitigation. The FeNCCoSA-C3N4/PMS complex contributed to > 60% of paracetamol degradation, whereas radical species and high-valent metal-oxo species contributed 13.3%–15.6% of paracetamol degradation. FeNCCoSA-C3N4/PMS preferentially oxidizes organic pollutants containing electron-donating moieties but may be negatively affected by inorganic carbon and chloride ions. Synthesizing the bimetallic cluster/atom catalyst offers a new way of achieving efficient PMS activation and pollutant oxidation via catalyst/PMS complex formation and electron-transfer reactions.