Breaking the oxo-wall for Co(IV)-oxo species and their nanoconfined catalytic performance within Ce-Co lamellar membrane.

Abstract

Co(IV) = O-mediated Fenton-like processes show great potential for water remediation but are fundamentally limited by the "oxo-wall" effect, which imposes prohibitive activation energies for Co(IV) = O bond formation and stabilization. Herein, by unifying thermodynamic analysis with the "oxo-wall" constraint mechanism, we establish the comprehensive theoretical framework for Co(IV) = O-dominated non-radical Fenton-like oxidation pathways. We design a Ce-Co tetra-(4-carboxyphenyl) porphyrin framework (Ce-Co TCPP), where Ce(IV)-based oxide linkers induce long-range electronic modulation, enhancing electronic delocalization at Co-N₄ sites. This significantly reduces electron occupancy in Co-O antibonding orbitals, thereby effectively circumventing "oxo-wall" constraints. Combined experimental and computational analyses confirm that Co(IV) = O species dominate in the Ce-Co TCPP/peroxymonosulfate (PMS) system, where synergistic electron transfer and proton transfer processes significantly lower activation barriers. Practically, the lamellar Ce-Co TCPP membrane/PMS system achieves desirable water permeability (126.97 L·m^-2·h^-1·bar^-1 (LMHB)), high pollutant degradation efficiency (0.0717 ms^-1), robust anti-interference capability, and long-term operational stability (95 h), which can be attributed to the shortened mass transport pathways and the approximately 1000-fold enrichment of Co(IV) = O complexes within membrane nanoconfined channels. This work offers an innovative strategy for sustainable Co(IV) = O-mediated advanced oxidation processes in water treatment.