Confining Asymmetrically Coordinated Cobalt Single-Atoms/Clusters on Holey MXene for Ultrafast Fenton-Like Catalysis

Abstract

Developing single-atom catalysts (SACs) with asymmetric coordination configurations is essential for enhancing peroxymonosulfate (PMS) activation in Fenton-like reactions. However, precisely regulating the electronic structure and coordination environment of metal centers to further improve activation kinetics remains a key challenge. Herein, we designed asymmetric CoN1O2 single atoms (SAs) sites and Co nanoclusters (NCs) that were spatially confined in highly graphitized carbon layers and supported on holey MXene nanosheet (CoSA-NC/H20MX) via a dual-coordination microenvironment strategy. The CoSA-NC/H20MX catalyst demonstrated exceptional performance on bisphenol A (BPA) removal, achieving a corrected rate constant (kvalue) of 2750 min−1 M−1 and a total organic carbon removal efficiency of 78.2%. Mechanistic studies revealed that BPA removal was dominated by a nonradical electron transfer process (ETP, ∼100%), which facilitated rapid polymerization of BPA. Density functional theory calculations demonstrated that Co NCs synergistically enhanced the ability of asymmetric CoN1O2 SAs sites to adsorb and activate PMS, significantly accelerating interfacial charge transfer. Furthermore, a catalytic membrane fabricated by crosslinking of CoSA-NC/H20MX and graphene achieved 100% BPA removal in single-pass mode with a hydraulic retention time of just 40 ms over 24 h of continuous operation. This work provides new insights into designing high-performance catalysts for pollutant removal via ETP-driven polymerization pathways.