Electron Delocalization Realizes Speedy Fenton-Like Catalysis over a High-Loading and Low-Valence Zinc Single-Atom Catalyst.

A zinc (Zn)-based single-atom catalyst (SAC) is recently reported as an active Fenton-like catalyst; however, the low Zn loading greatly restricts its catalytic activity. Herein, a molecule-confined pyrolysis method is demonstrated to evidently increase the Zn loading to 11.54 wt.% for a Zn SAC (Zn SA -N-C) containing a mixture of Zn-N 4 and Zn-N 3 coordination structures. The latter unsaturated Zn-N 3 sites promote electron delocalization to lower the average valence state of Zn in the mix-coordinated Zn-N x moiety conducive to interaction of Zn SA -N-C with peroxydisulfate (PDS). A speedy Fenton-like catalysis is thus realized by the high-loading and low-valence Zn SA -N-C for PDS activation with a specific activity up to 0.11 min L -1 m -2 , outstripping most Fenton-like SACs. Experimental results reveal that the formation of Zn SA -N-C-PDS* complex owing to the strong affinity of Zn SA -N-C to PDS empowers intense direct electron transfer from the electron-rich pollutant toward this complex, dominating the rapid bisphenol A (BPA) elimination. The electron transfer pathway benefits the desirable environmental robustness of the Zn SA -N-C/PDS system for actual water decontamination. This work represents a new class of efficient and durable Fenton-like SACs for potential practical environmental applications.