Interfacial electronic structure engineering on nano-confined cobalt nanoparticles to enhance Fenton-like reaction

Rational design of nano-confined cobalt-based heterogeneous catalysts for peroxymonosulfate (PMS) activation remains challenging in Fenton-like systems, particularly in regulating interfacial electronic structures and establishing explicit electron transfer-activity correlations. To address this, we engineered a hierarchically structured Co@C-CNT composite featuring cobalt nanoparticles encapsulated in N-doped carbon polyhedrons interconnected by carbon nanotubes, forming a unique one-dimensional beads-on-string architecture. The strategic integration of CNTs significantly enhanced interfacial electron transfer kinetics, endowing the Co@C-CNT/PMS system with exceptional catalytic performance for carbamazepine degradation (k_obs = 0.2281 min⁻¹), demonstrating a twofold enhancement over the CNT-free Co@C counterpart (0.1053 min⁻¹). Mechanistic studies through DFT calculations unveiled that the CNT-induced electronic string effect synergistically modulates the d-band center of confined Co sites and facilitates electron donation to PMS, preferentially cleaving O-H bonds to generate metastable SO₅^•- intermediates. This electronic configuration promotes selective O1₂ generation through PMS self-decomposition while suppressing radical pathways. The optimized system exhibited high efficiency across electron-rich pollutants, maintained robust performance in real wastewater matrices, and demonstrated operational stability in continuous-flow reactors. This work elucidates the critical role of electronic structure engineering in manipulating PMS activation pathways and provides a paradigm for designing advanced oxidation catalysts through targeted electron transport optimization.