Surface Al and Co coordination for peroxymonosulfate activation: Identification and mechanism

Deciphering the metal-support interaction-oriented catalysis on millimeter-scaled catalysts is highly desirable yet remains scarce in Fenton-like catalysis. Herein, we fine-tune the support-surface reconstruction of Co2AlO4 on γ-Al2O3 millispheres and reveal the origins of its activity in peroxymonosulfate activation by nuclear magnetic resonance and X-ray photoelectron/adsorption spectroscopy. Calcination of γ-Al2O3 supports rearranged their surface octahedral, tetrahedral and pentacoordinate Al3+. The reconstructed tetrahedral and pentacoordinate Al3+ as binding sites regulated the formation of Co2AlO4 with coordinated Co3+/Co2+ redox centers via strong metal-support interactions. The activities of tailored Co2AlO4 @Al2O3 millispheres in activating peroxymonosulfate follow different binomial models, highly relying on their Co3+/Co2+ ratio, contents of lattice O and pentacoordinate Al3+. The Co-O-Al bonds endow the millimeter-scaled Co2AlO4 @Al2O3 with robust catalytic activity, stability and reusability. The exposed Co2AlO4 (200) surface is responsible for the decomposition of PMS into produce SO4• and 1O2 as the dominant oxidants for water detoxification.