Carbon matrix with atomic dispersion of binary cobalt/iron-N sites as efficient peroxymonosulfate activator for organic pollutant oxidation

Monometallic single atom catalysts have exhibited excellent catalytic capacity due to their unique structural features. However, it remains challenging to promote the limited number of active sites and realize high-efficiency and stability during Fenton-like catalysis. Herein, a nitrogenized graphitic carbon matrix containing Fe-Co dual single atoms (FeCoNC) manifested enhanced catalytic capacity in persulfate activation for tetracycline hydrochloride (TC) oxidation. Nonradical singlet oxygen (1O2) was identified as dominant reactive species in both FeCoNC and CoNC systems, while the formation pathways of 1O2 and TC catalysis processes were distinct different. 57Fe Mössbauer spectroscopy and theoretical calculations revealed that the dynamic electronic structure and covalency of Fe-N/Co-N bond configuration after coordinating with a second neighboring metal atom induced promoted electron transfer and tuned reactive species transformation pathways. Benefiting from the optimized N3-Fe-Co-N3 structure and synergistic effect of dual metal sites, the FeCoNC catalyst was endowed with lowered reaction barriers, excellent adaptability and stability, demonstrating promising practical application potential. This work unveiled the intrinsically regulated mechanism of dual single metal sites towards refractory organic oxidation and delivered enhanced understanding of covalency and electronic configuration on PMS-AOPs based catalysis processes.