Electronic structure engineering of CoFe dual single-atom sites on carbon aerogel for enhanced visible-light-assisted peroxymonosulfate activation

Co Fe dual single-atom sites tailor electronic structure to boost PMS activation. • 97.7% ± 2.6% tetracycline removal in 15 min ( k  = 0.22 min −1 ), outperforming single-atom catalysts. • Fixed-bed reactor sustains ∼95% tetracycline removal for 120 h with lower ecotoxicity. Single-atom catalysts (SACs) for peroxymonosulfate (PMS) activation are often constrained by the limited electronic tunability of isolated mono-metal centers, which weakens oxidant adsorption and interfacial charge transfer. Herein, we overcome this limitation by constructing a Co Fe dual single-atom catalyst anchored on a nitrogen-doped carbon aerogel (Co–Fe/NCNA) for visible-light-assisted tetracycline degradation. Spectroscopic and synchrotron analyses confirm that atomically dispersed Co N 3 and Fe N 4 sites coexist within a hierarchically porous three-dimensional carbon framework, ensuring high active-site accessibility and rapid mass transport. The Co–Fe/NCNA system achieves 97.7% ± 2.6% tetracycline (TC) removal within 15 min ( k  = 0.22 min −1 ), dramatically outperforming single-metal and metal-free analogues. Density functional theory calculations indicate that the coupled Co Fe sites reconstruct the local electronic structure, elevate the d-band center, strengthen PMS adsorption, and reduce the activation barrier for PMS conversion to 0.30 eV. The TC degradation proceeds through a cooperative radical/nonradical oxidation network, in which h + -mediated oxidation acts as the primary apparent pathway, while 1 O 2 , ·O 2 − , ·OH, SO 4 · − , and possible high-valent metal-oxo-like species contribute synergistically or serve as auxiliary pathways. Notably, a fixed-bed continuous-flow reactor sustains ∼95% tetracycline removal over 120 h, and outstanding activity is retained under natural sunlight. This work establishes electronic structure engineering of dual single-atom sites as a powerful strategy to boost visible-light-driven PMS activation for sustainable water remediation. Under visible-light irradiation, the Co Fe dual single-atom sites regulate the local electronic structure, optimize the d-band center, and promote photogenerated charge separation and interfacial electron transfer, thereby enabling efficient peroxymonosulfate (PMS) activation. Through the synergistic cooperation of electron-mediated PMS reduction, hole-mediated PMS oxidation, and Co/Fe self-cycling, radical and non-radical reactive species are generated to construct an integrated oxidation network, which drives the efficient degradation and mineralization of tetracycline. Download: Download high-res image (401KB) Download: Download full-size image