FeSeS@C cage-in-cage superlattices for peroxymonosulfate activation: Surface acidity regulates Fe spin state

Two-dimensional cage-in-cage carbon-coated FeSeS superlattices with varying degrees of sulfidation (FeSeS@C) are developed for activating peroxymonosulfate (PMS) to effectively degrade diatrizoic acid (DTZ), and the intrinsic origin that govern the activity of FeSeS@C are deeply elucidated. Experimental and theoretical analyses manifested that proper sulfidation led to increased surface acidity of FeSeS@C. The high surface acidity can optimize the exposure and spin state of Fe sites for FeSeS@C-4, a high spin state of Fe (6.27 μ) not only regulating PMS adsorption for enhancing the charge density, but also expediting interfacial charge deliver to trigger the efficient PMS activation. Therefore, among FeSeS@C, FeSeS@C-4 exhibited the best degradation performance for DTZ, with first-order kinetic rate constants (k) of 0.232 min and degradation rate of 100 %. This study demonstrates a novel application of cage-in-cage superlattices in environmental remediation and offers new insights into the mechanism of PMS activation by sulfur modification Fe-based catalysts.