CoO<sub>x</sub> clusters-decorated IrO<sub>2</sub> electrocatalyst activates NO<sub>3</sub><sup>-</sup> mediator for benzylic C-H activation.

Mi, Ziyu; Li, Yuke; Wu, Chao; Zhang, Mingsheng; Cao, Xun; Xi, Shibo; Zhang, Jia; Leow, Wan Ru · Nat Commun · 2025

basic_science · Level V

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Abstract

Electrochemical conversion of petrochemical-derived hydrocarbons to high-value oxygenates can utilize renewable energy and reduce carbon emissions. However, this involves the challenging activation of inert C(sp<sup>3</sup>)-H bonds at room temperature. Here, we introduce an electrocatalyst:mediator assembly in which CoO<sub>x</sub> clusters-decorated IrO<sub>2</sub> electrocatalyst activates NO<sub>3</sub><sup>-</sup> mediator to a highly reactive radical capable of abstracting a hydrogen atom from benzylic C-H. The interface between CoO<sub>x</sub> and IrO<sub>2</sub> promotes NO<sub>3</sub><sup>-</sup> activation by facilitating the desorption of NO<sub>3</sub><sup>●</sup> radical for subsequent reaction. Our strategy is demonstrated through the selective oxidation of toluene to benzaldehyde with high Faradaic efficiency of 86( ±1)% at 25 mA/cm<sup>2</sup>, a factor of >3 times higher than the bare electrocatalyst. The electrocatalyst:mediator assembly is operated stably for 100 h, with minimal decline in performance. When translated into a flow system, a Faradaic efficiency of 60( ±4)% at 200 mA/cm<sup>2</sup> was achieved.