Unlocking catalytic potential of single-atom Zn on N-doped MXene through intensive metal-support interaction for high-efficiency Fenton-like catalysis

Abstract

Constructing high-efficiency metal single-atom Fenton-like catalyst remains challenging due to unsatisfactory carrier development and insufficient understanding of metal-support interaction (MSI). In this work, N-doped MXene supported single-atom Zn (Zn-N-MXene) catalyst was designed and constructed, which produced strong MSI effect for dramatically modulating the inert electronic structure of Zn and transformed it into a green and efficient peroxymonosulfate (PMS) activator. The Zn-N-MXene-3 with optimal Zn loading demonstrated an ultrahigh turnover frequency (TOF) of 3.16 min-1 for sulfamethoxazole (SMX) degradation, which was approximately 4.0 and 1.2×103 times higher than that of single-atom Zn anchored on N-doped carbon nanotube (common catalyst support) and homogeneous Zn2+ (no support), respectively, and greatly outperformed those of the state-of-the-art metal single-atom catalysts. Moreover, the Zn-N-MXene-3 exhibited long-term effectiveness and stability in continuous-flow actual water decontamination. Theoretical calculations and experimental results collectively revealed the N-doped MXene played dual roles in improving the catalytic activity of Zn center: For one thing, it optimized bonding states distribution in Zn 3d orbitals and upshifted the d-band center of Zn, resulting in enhanced PMS adsorption and reduction into radicals (mainly •OH); for another, it enabled distinct electron enrichment on Zn center, leading to the formation of more active Zn2+ species for participating in PMS activation.