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

Abstract

Oxygen vacancy (VO) is attracting extensive interest in heterogeneous peroxymonosulfate (PMS) activation, but its role remains elusive for water treatment. Herein, we constructed VO-tuned cobalt-based perovskite LaCoO3-VO, achieving superior activity (0.335 min−1) than LaCoO3 (0.124 min−1) for iohexol degradation. Nevertheless, VO 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 VO manipulation. DFT calculations suggest reactant HSO5− is prone to attach defect site for elongated O-O bond. Experimental and theoretical results reveal the contributions of VO 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.