Powerful Fenton-like reactions derived from montmorillonite modulated Co single atom: Key role of heterogeneous high-valent Co (IV)-oxo

Understanding and controlling the structure-activity relationship of single atom catalysts (SACs) is crucial for optimizing their catalytic performance. This study investigated the influence of montmorillonite (MT) as a support material on the microstructure of SACs, and how these influences modulate the catalytic performance and mechanism of peroxymonosulfate (PMS) activation. The enrichment effect within the MT interlayer space significantly enhanced the interaction between organic pollutant molecules, PMS, and active sites, thereby improving adsorption capacity and mass transfer efficiency. This enhancement increased the likelihood of subsequent peroxide bond cleavage, enabling the system to exhibit a greater capacity to generate high-valent Co (IV)-oxo and free radicals (SO 4 •− and • OH), leading to a higher removal efficiency of sulfamethoxazole (SMX). The introduction of MT altered the pathway of SMX removal, and the CoSAC@MT/PMS system predominantly degraded SMX into intermediate products with lower molecular weights and negligible fluorescence signals. Additionally, the incorporation of MT significantly boosted the yield of SACs synthesized via traditional pyrolysis methods, offering a novel strategy to reduce preparation costs and achieve large-scale synthesis.