Remote Modulation of Single-Atom Catalyst Boosts High-Valent Cobalt-Oxo Species Generation for Water Purification and...

With a high redox potential and long half-life, high-valent cobalt-oxo species (Co(IV)═O) hold promise for water purification by eliminating persistent contaminants. However, the inefficient and unsustainable generation of Co(IV)═O limits its practical application. In this work, a phosphorus (P)-doped cobalt single-atom catalyst (Co─N₆/C─P) is developed, where P-substituted nitrogen (N) atoms are coordinated to the cobalt site at meta-positions. This remote modulation reduces the charge density of the cobalt site and positively shifts the d-band center of the cobalt atom, thereby lowering the energy barrier for Co(IV)═O generation. The P-doping increases the turnover frequency of the cobalt center by 3.5 times and the steady-state concentration of Co(IV)═O by 2.7 times. The (Co─N₆/C─P)/peroxymonosulfate (PMS) system exhibits a pollutant degradation kinetic constant three times higher than that of Co─N₆/C, surpassing most reported single-atom catalytic PMS systems. A continuous-flow reactor based on Co─N₆/C─P achieves over 87% contaminant removal after 24 h of operation. The treated real wastewater exhibits exceptionally low cytotoxicity (2.96 mg-phenol L^-1) and genotoxicity (0.08 µg-4-NQO L^-1) to mammalian cells, enhancing water safety. This study presents a reliable approach for the removal of persistent contaminants and the reduction of toxicity through efficient Co(IV)═O generation enabled by a remote modulation strategy.