Synergy and primacy of crystal morphology and crystalline phase: Driving efficient peroxymonosulfate activation by...

To gain an in-depth understanding of structure-activity relationships (SARs) governing catalyst design and practical applications, we synthesized rod-like (or plate-like) CoSe₂ catalysts with cubic (or orthorhombic) crystalline phase for peroxymonosulfate (PMS) activation. Among these catalysts, the crystalline phase exerted a dominant regulatory effect on catalytic performance, while morphology played a secondary role. Notably, the rod-shaped CoSe₂ with cubic crystalline phase (R-C-CoSe₂) enabled complete degradation of ciprofloxacin (CIP) within 10 min with a first-order kinetic constant of 0.424 min^-1 - outperforming its orthorhombic and plate-like counterparts. Experimental characterizations combined with density functional theory (DFT) calculations confirmed that the crystal phase-dominated R-C-CoSe₂ possessed enhanced electron transfer kinetics and moderate PMS adsorption affinity, which are the key factors accounting for its superior catalytic activity. Moreover, R-C-CoSe₂ demonstrated excellent degradation performance for various pollutants and real water matrices. Furthermore, LC-MS and DFT calculations were employed to elucidate possible degradation pathways of CIP in the R-C-CoSe₂/PMS system and evaluate the toxicity evolution of degradation intermediates. This work emphasizes the critical role of crystal phase-morphology synergy in boosting catalytic performance, offering valuable insights for deciphering SARs and guiding the rational design of high-efficiency PMS activators for environmental remediation.