Spin-State-Dependent Peroxymonosulfate Activation of Single-Atom M-N Moieties via a Radical-Free Pathway

Transition metal catalysts are known to activate persulfate, but the properties that govern the intrinsic activity of these catalysts are still unknown. Here, we developed a series of catalysts with transition metals anchored on carbon nanotubes (denoted M-N-CNTs, where M = Co, Fe, Mn, or Ni) containing single-atom M-N moieties, to activate peroxymonosulfate for the efficient nonradical oxidation of sulfamethoxazole. The spin state of M-N-CNTs strongly determined their catalytic activity. A large effective magnetic moment with a high spin state (e.g., Co-N) favored the overlap of d orbitals with oxygen-containing adsorbates (such as peroxo species) on metal active sites and promoted electron transfer, which facilitated peroxymonosulfate adsorption and enhanced the oxidation capacity of the reactive species. These findings advance the mechanistic understanding of transition metal-mediated persulfate activation and inform the development of efficient spintronic catalysts for environmental applications.