Breaking scaling relation of single-atom site via energy storage-release effect from adjacent carbon vacancy for low-temperature-resistant Fenton-like catalysis

To realize efficient antibiotics degradation in low-temperature water, single-atom FeN4 sites are engineered near carbon vacancies in a porous catalyst (PCvFe1-5) via thermal-etching and pyrolysis. The high-specific-surface-area (2202.80 m2 g−1) carbon support and dispersive Fe atoms co-enrich sulfamethoxazole and peroxymonosulfate to enhance the reactant collision frequency. Carbon vacancies allow the catalyst to deform for storing the peroxymonosulfate adsorption energies at FeN4 sites, which are subsequently released to facilitate -SO4H desorption for rapid site regeneration. This breaks the scaling relation suffered by single-atom sites, thereby reducing the thermodynamic energy barrier. Consequently, a low-temperature-resistant Fenton-like system with ultralow activation energy of 9.06 kJ mol−1 is constructed for sulfamethoxazole degradation. The normalized kinetic rate constant at 2 ℃ exceeds that of reported catalysts working at 25/30 ℃ by 1–2 orders of magnitude. Moreover, due to the special site configuration, PCvFe1-5 degrades sulfamethoxazole via both long-range catalyst-mediated electron transfer and short-range direct collision oxidation. [Display omitted] •Single-atom FeN4 sites are preferentially engineered near carbon vacancies (Cv).•The catalyst rapidly degrades sulfamethoxazole (SMZ) near 0 °C via PMS activation.•Both mediated electron transfer and direct collision oxidation control SMZ removal.•High reactant collision frequency is obtained by co-enrichment of SMZ and PMS.•Cv breaking scaling relation of single-atom site causes ultralow activation energy.