Boron coordination engineering of single-atom Cu sites unveils the adsorption-activation trade-off in Fenton-like catalysis.

Balancing oxidant adsorption and activation at isolated metal sites remains challenging in Fenton-like catalysis, as strong binding limits turnover while weak interaction impedes oxidant conversion. Here, polyphthalocyanine-derived Cu single atoms serve as a structurally defined platform to systematically screen and optimize boron coordination (Cu-NxBy), revealing the adsorption-activation trade-off in peroxymonosulfate (PMS) activation on Cu single-sites. Among the examined structures, the first-shell Cu-N2B2 motif is identified as the optimal coordination, providing the most effective balance between PMS adsorption-activation. First-shell B substitution induces tensile strain in the Cu-N framework and upshifts the Cu d-band center, strengthening Cu-PMS coupling, placing HSO5- binding within a favorable adsorption-desorption window, and accelerating proton-electron transfer during activation. In this system, Cu serves as the redox-active center for PMS conversion, whereas B tunes charge distribution and stabilizes intermediates. The optimized Cu-N2B2 site drives coupled oxidation with SO4•- and high-valent Cu(III)-O species, enhancing reactivity toward diverse pollutants. Cu-N2B2-like boron-coordinated polyphthalocyanine copper (PPcCu-N2B2) achieves removing bisphenol A within 5 min with a turnover frequency of 1.16 min-1, and it sustains continuous operation with a purification capacity of 120 L g-1 catalyst. This work establishes boron coordination as an effective strategy to resolve the adsorption-activation trade-off in Fenton-like catalysis and guides the design of durable single-atom catalysts for water purification.