Breaking the activity-selectivity trade-off in Fenton-like catalysis by d-orbital modulation of single-atom sites within a nano-island-like structure

Direct electron transfer (ETP) during peroxymonosulfate (PMS) activation enables selective, matrix-resistant organic contaminants oxidation, yet its precise control over competing radical pathways remains elusive. Here we report a nano-island-like single-atom catalyst- carbon nitride islands immobilize cobalt single atoms on reduced graphene oxide (CoN₃C/rGO)- that leverages an island-sea architecture to direct PMS activation toward ETP. Experimental and density functional theory (DFT) analyses show an rGO induced elevation of the Co d-band center and a sharpened d_z2 orbital near the Fermi level, promoting directional hybridization with PMS p orbitals and suppressing antibonding occupation. Consequently, CoN₃C/rGO/PMS degrade bisphenol A (BPA) completely within 5 min, with ~94% contribution from ETP. Furthermore, catalytic membrane coatings enable stable 100 h continuous operation in diverse real water matrices with minimal Co leaching. Our results demonstrate a design principle-orbital-level modulation via island-sea architectures to reconcile activity and selectivity in Fenton-like systems and advance translating practical water treatment technologies based on single-atom electronic control.