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

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 (Co_SA-NC/H₂₀MX) via a dual-coordination microenvironment strategy. The Co_SA-NC/H₂₀MX catalyst demonstrated exceptional performance on bisphenol A (BPA) removal, achieving a corrected rate constant (k_value) 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 Co_SA-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.