Single-atom sites in metal–N4 configuration for efficient abatement of refractory organic pollutants via Fenton-like reaction

Abstract

Single-atom metal catalyzed peroxymonosulfate (PMS) activation shows great potential in water treatment; and the activity of various metal centers have been explored. The properties of the support contribute significantly to the catalytic performance of the metal centers. The knowledge on the intrinsic distinctions of the elements in single-atom catalyzed PMS activation is, however, relatively in lack. In this work, via a facile one-step method, three representative elements of Fe, Co, and Cu were configured in a metal − N4 structure and anchored on N-doped carbon matrix with similar composition and structure. The atomic dispersity of the metal centers was experimentally substantiated by electronic microscopic technique in atomic scale and X-ray absorption spectroscopy. All these single-atom metal centers exhibit high activity in PMS activation for selective degradation of the organic pollutants, while the durability of the single-atom metal centers is vastly distinct as examined in continuous flow-mode. The water treatment capacity is in an order of Co − N4 ≈ Fe − N4 ≫ Cu − N4 for the elimination of 0.1 mM 4-chlorophenol from water. Based on the analysis of the qunching effect by various probe molecules and electron spin resonance spectra at various reaction conditions, the high-valent Co(IV)O species is proposed to be the predominant active species for pollutant degradation in Co − N4 catalyzed PMS activation. The findings in this work sheds light on the desgin of efficent and durable single-atom catalyst for water treatment.