A Green and Efficient Electrocatalytic Route for the Highly‐Selective Oxidation of C−H Bonds in Aromatics over 1D Co$_3$O$_4$ ‐Based Nanoarrays

Electrocatalytic oxidation of C-H bonds in hydrocarbons represents an efficient and sustainable strategy for the synthesis of value-added chemicals. Herein, a highly selective and continuous-flow electrochemical oxidation process of toluene to various oxygenated products (benzyl alcohol, benzaldehyde, and benzyl acetate) is developed with theelectrocatalytic membrane electrodes (ECMEs). The selectivity of target products can be manipulated via surface and interface engineering of Co$_3$O$_4$-based electrocatalysts. We achieved a high benzaldehyde selectivity of 90% at a toluene conversion of 47.6% using 1D Co$_3$O$_4$ nanoneedles (NNs) loaded on a microfiltration (MF) titanium (Ti) membrane, i.e, Co$_3$O$_4$ NNs/Ti. In contrast, the main product shifted to benzyl alcohol with a selectivity of 90.1% at a conversion of 32.1% after modifying MnO$_2$ nanosheets (NSs) on Co$_3$O$_4$ NNs/Ti (Co$_3$O$_4$@MnO$_2$/Ti) catalyst. Moreover, benzyl acetate product can be obtained with a selectivity of 92% at a conversion of 58.5% at high current density (>1.5 mAcm$^{-2}$),demonstrating that the pathway of toluene oxidation is readily maneuvered. DFT results reveal that modifying MnO$_2$ on Co$_3$O$_4$ optimizes the electron structure of Co$_3$O$_4$@MnO$_2$/Ti and modulates the adsorption behavior of intermediate species. This work demonstrates a sustainable, efficient, and continuous-flow process for precise control over the production selectivity of value-added oxygenated derivatives in the electrochemical oxidation of aromatic hydrocarbons.