Identifying the role of oxygen vacancy on cobalt-based perovskites towards peroxymonosulfate activation for efficient iohexol degradation

Oxygen vacancy (V O ) is attracting extensive interest in heterogeneous peroxymonosulfate (PMS) activation, but its role remains elusive for water treatment. Herein, we constructed V O -tuned cobalt-based perovskite LaCoO 3 -V O , achieving superior activity (0.335 min -1 ) than LaCoO 3 (0.124 min -1 ) for iohexol degradation. Nevertheless, V O did not directly serve as reactive sites, indicated by prohibited contaminant degradation via targeted poisoning of cobalt sites. Systemic electrochemical and spectroscopic measurements illustrate facile transformation of cobalt ions, increased charge density of depletion layer and low transfer resistance are attributed to V O manipulation. DFT calculations suggest reactant HSO 5 − is prone to attach defect site for elongated O-O bond. Experimental and theoretical results reveal the contributions of V O include adjusting PMS adsorption configuration, weakening lattice restraining of cobalt ions, reducing reaction barrier and optimizing electronic structures on perovskites. Our work attempts to understand energetic and kinetic factors of deficiency strategy for rational PMS-based degradation. • Targeted poisoning of cobalt ions identifies reactive sites. • V O is not the direct reactive centers activating PMS • Energetics of perovskite affect the height of reaction barrier. • V O increases interfacial charge density and accelerates kinetics. • DFT calculations illustrate V O enhances PMS adsorption and stretching.