Electrocatalytic methane conversion via in-situ generated superoxide radicals in an aprotic ionic liquid.

Abstract

The electrochemical activation and partial oxidation of methane are highly attractive to enable the direct conversion in a sustainable and decentralized way. Herein, we report an electrochemical system in a non-diaphragm electrochemical bath to convert CH₄ to CH₃OH and CH₃CH₂OH at room temperature, in which V₃O₇·H₂O as the anodic catalyst to activate CH₄ and an aprotic ionic liquid [BMIM]BF₄ as supporting electrolyte to control superoxide radicals (O₂^-) as the main active oxygen species generated on cathode. As a result, methanol and ethanol were identified as the liquid products, and the superior methanol Faraday efficiency (FE) of 32.2 % and selectivity of 76.8 % can be reached. Molecular dynamics (MD) simulation indicates that interaction between CH₄ molecules and [BMIM]BF₄, which enhances the mass transfer in electrochemical reaction. Density function theory (DFT) calculation results suggest that the V sites in V₃O₇·H₂O enhanced the chemisorption and dissociation of CH₄ molecules on anode surface, then superoxide radicals (O₂^-) are supposed to be involved in the formation of methanol and ethanol.