Heterogeneous electrocatalysis is an advanced tactics to oxidize organic sulfides into value-added products, concurrently being accompanied with hydrogen production in the aqueous electrolyte. However, the insufficient oxidizing ability of redox mediators and competitive oxygen evolution reaction (OER) inhibited the late-stage oxygenation of thioethers to produce sulfones. Herein, a RuO₂-loaded Co₃O₄ electrocatalyst (Ru-Co₃O₄) was constructed to oxidize thioethers at the potential range of 0.7–0.8 V (vs. Ag/AgCl) at which the OER did not sharply occur, and various sulfoxides and sulfones were produced selectively with moderate to good yields. Mechanism studies revealed that the Ru-Co₃O₄ electrocatalyst afforded Ru⁴⁺ active species and hydroxyl radicals (·OH) at a low potential. The generated Ru^Ⅳ/Ru^Ⅲ redox couple was responsible for the oxidation of sulfides into sulfur-related cation radicals which then reacted with ·OH and deprotonated to form oxygenation products. This work provided a reasonable proposal for the design of heterogeneous electrocatalysts, which could effectively drive the organic oxygenation reactions.

中文翻译：

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对 RuIV./RuIII. 和 ·OH-co 参与在 Ru-Co3O4 电催化剂上将硫醚选择性氧化成亚砜和砜


非均相电催化是一种将有机硫化物氧化成增值产品的先进策略，同时伴随着水性电解质中的氢气产生。然而，氧化还原介质的氧化能力不足和竞争性析氧反应 （OER） 抑制了硫醚的后期氧化生成砜。在此，构建了负载 RuO₂ 的 Co₃O₄ 电催化剂 （Ru-Co₃O₄），以在 0.7–0.8 V（相对于 Ag/AgCl）的电位范围内氧化硫醚，在该范围内 OER 不会急剧出现，并且选择性地生产各种亚砜和砜，产率中等到良好。机理研究表明，Ru-Co₃O₄ 电催化剂提供了 Ru⁴⁺ 活性物质和羟基自由基 （·OH） 的生成的 Ru^IV./Ru^III. 氧化还原对负责将硫化物氧化成硫相关的阳离子自由基，然后与 ·OH 并去质子化形成氧合产物。这项工作为非均相电催化剂的设计提供了合理的建议，可以有效地驱动有机氧化反应。