Accelerated Fe³⁺/Fe²⁺ cycle in Mo2C-based Fe catalyst to promote peroxymonosulfate activation

The harmful impact of organic pollutants on aquatic ecosystems underscores the pressing need for effective remediation. While activating peroxymonosulfate (PMS) with Fe catalyst offers a promising approach for eliminating these pollutants, its widespread use is hindered by the sluggish regeneration of Fe²⁺ from Fe³⁺. Here, this study demonstrates for the first time that combining an Fe catalyst with Mo₂C (Fe-Mo₂C) enhances the Fe³⁺/Fe²⁺ cycle, thereby improving PMS activation. The Fe-Mo₂C/PMS system achieved near-complete degradation of carbamazepine (CBZ) within only 8 min, with an impressive observed rate constant (k_obs) of up to 0.624 min^-1, about 15 times greater than that of Fe-C catalyst. It also exhibits the capability to degrade a broad range of common antibiotics, phenols, and dye-like organic compounds. Through electron paramagnetic resonance (EPR) analysis and quenching experiments, it was verified that hydroxyl radicals (·OH), sulfate radicals (SO₄^·-), singlet oxygen (¹O₂), and superoxide radicals (·O₂^-) species during the reaction, with the former three serving as the primary active species. These findings offer a hopeful avenue for the systematic development and enhancement of catalysts specifically designed to efficiently remediate organic pollutants in wastewater.