The overlooked role of high-valent cobalt-oxo species (Co(IV)) in the Co(II)/peroxymonosulfate (PMS) process was uncovered recently using methyl phenyl sulfoxide (PMSO) as the probe. Herein, we further interestingly found that Co(IV) could trigger hydroxyl radical (^•OH) formation, resulting in the oxidized products distribution of PMSO heavily relied on the relative concentration of PMSO. More significantly, the generation of a series of ¹⁸O-labeled hydroxylated products (i.e., hydroxylated methyl phenyl sulfone, nitrobenzene and 4-nitrobenzoic acid) in H₂¹⁸O conclusively verified that ^•OH was triggered by Co(IV) species. Density functional theory calculation demonstrated that Co(IV) initiated ^•OH formation via oxo ligand protonation-induced valence tautomerization. Moreover, the oxidative contribution of Co(IV) and ^•OH on organic degradation was specifically dependent on the type and concentration of the substrate. This study provided deeper insights into the evolution pathway of ^•OH mediated by Co(IV) species and enriched the understandings on the collaborative oxidation mechanism in Co(IV)-involved processes.

最近使用甲基苯基亚砜（PMSO）作为探针发现了高价钴氧物种（Co（IV））在 Co（II）/过硫酸盐（PMS）过程中被忽视的作用。在此，我们进一步有趣地发现，Co(IV) 可以触发羟基自由基 ( ^• OH) 的形成，导致 PMSO 的氧化产物分布严重依赖于 PMSO 的相对浓度。更重要的是，在 H ₂ ¹⁸ O 中生成的一系列¹⁸ O 标记的羟基化产物（即羟基化甲基苯砜、硝基苯和 4-硝基苯甲酸）最终证实了^• OH 是由 Co(IV) 物种触发的。密度泛函理论计算表明 Co(IV) 引发了^•通过氧代配体质子化诱导的价互变异构化形成 OH。此外，Co(IV) 和^• OH 对有机降解的氧化作用具体取决于底物的类型和浓度。该研究为Co(IV)物种介导的^• OH的演化途径提供了更深入的见解，并丰富了对Co(IV)相关过程中协同氧化机制的理解。