A high-efficient iron-based heterogeneous catalyst is desired to active peroxymonosulfate (PMS). Due to a large catalytic contribution of atomically dispersed Fe-N_x sites, single-atom iron-nitrogen-carbon catalysts exhibit superior performance in the catalytic activation of PMS. Herein, a sequence of Fe-N-C SACs with atomically dispersed Fe-N_x sites, Fe_SA-N-C and Fe_SA-N/C, were prepared from Fe-doped ZIF-8 and FePc@ZIF-8, respectively. Single-atom Fe-N_x sites were confirmed to be the main active sites for PMS activation. Fe_SA-N/C-20 with a higher density of Fe-N_x sites exhibited superior catalytic performance to N/C, Fe_SA-N-C, Fe_SA-N/C-15, and Fe_SA-N/C-25 for BPA degradation. Integrated with chemical quenching experiments, electron spin resonance (ESR), in-situ Raman spectra, and electrochemical analysis, a nonradical pathway was demonstrated to dominate the degradation of BPA in the PMS + Fe_SA-N/C-20 system. More importantly, the nature of this nonradical pathway was found to be an electron-transfer regime instead of a high-valent iron or singlet oxygenation process. The BPA was adsorbed onto the Fe-N_x site by a “donor-acceptor complex” mechanism to form a nonradical PMS* intermediate during the process. Benefiting from this mechanism, the PMS + Fe_SA-N/C-20 system showed wide pH adaptation and high resistance to inorganic anions.

需要高效率的铁基非均相催化剂来活化过氧单硫酸盐（PMS）。由于原子分散的Fe-N _x部位具有很大的催化作用，因此单原子铁-氮-碳催化剂在PMS的催化活化中表现出优异的性能。在此，分别从掺杂Fe的ZIF-8和FePc @ ZIF-8制备具有原子分散的Fe-N _x位点的Fe-NC SAC序列，即Fe _SA -NC和Fe _SA -N / C。证实单原子Fe-N _x位点是PMS激活的主要活性位点。Fe - _Nx位点密度较高的Fe _SA -N / C-20的催化性能优于N / C，Fe _SA -NC，Fe_SA -N / C-15和Fe _SA -N / C-25用于BPA降解。与化学猝灭实验，电子自旋共振（ESR），原位拉曼光谱和电化学分析相结合，在PMS + Fe _SA -N / C-20系统中，非自由基途径被证明是BPA降解的主要因素。更重要的是，发现这种非自由基途径的性质是电子转移机制，而不是高价铁或单线态氧合过程。在此过程中，BPA通过“供体-受体复合物”机制吸附在Fe-N _x位点上，形成非自由基PMS *中间体。得益于此机制，PMS + Fe _SA -N / C-20系统显示出广泛的pH适应性和对无机阴离子的高耐受性。