Mn0.6Ce0.4O2/CNT electrocatalyst boosts the efficient electrocatalytic oxidation of toluene to benzoic acid

Abstract

Electrocatalytic toluene (TL) oxidation to produce benzoic acid (BAC) process is largely hindered due to sluggish kinetics associated with the transformation of the rate-determining step, because of weak TL adsorption and high rate-determining step energy barrier for difficult to dehydrogenate. Herein, we report Mn_xCe_1-xO₂/CNT catalyst for accelerated reaction kinetics. Theoretical and experimental studies indicate that Ce sites promote TL adsorption and polyvalent Mn modulates the electronic structure of Ce sites reducing the rate-determining step energy barrier. This results in increasing *C₆H₅CH₂ coverage and effectively accelerating TL oxidation reaction (TOR) kinetics. Excitingly, the Faraday efficiency (FE) and BAC yield of optimized Mn_0.6Ce_0.4O₂/CNT at 2.6 V vs. RHE could reach 85.9% and 653.9 mg h⁻¹ cm⁻², respectively. In addition, the Mn_0.6Ce_0.4O₂/CNT displays a high selectivity of 96.3% for BAC. Combining the TL oxidation reaction with hydrogen evolution reaction, the anion exchange membrane electrolyzer of Mn_0.6Ce_0.4O₂/CNT (+) ||Pt/C (−) can reach 100 mA cm⁻² at the voltage of 3.0 V, in which the BAC yield is 579.4 mg h⁻¹ cm⁻² and the FE is 83.6%. This work achieved high selectivity of TOR at industrial-relevant current densities of 100 mA cm⁻² at the low voltage for the first time.