Chloride-Promoted High-Rate Ambient Electrooxidation of Methane to Methanol on Patterned Cu–Ti Bimetallic Oxides

Abstract

The selective electrochemical methane oxidation reaction (MOR) has been challenging due to higher CH4 activation barriers and lower solubility at ambient conditions. Here, we synthesize a conductive gas-diffusion layer patterned with alternating squares of Cu and Ti oxides to achieve highly selective MOR at interfaces consisting of Cu–Ti bimetallic oxides. We observe high MOR faradaic efficiencies of ∼28% at ambient conditions and ∼72% at near-ambient conditions (40 °C) to value-added products such as CH3OH and HCOOH in a Cl–-mediated environment. Density function theory calculations suggest that despite TiO2 exhibiting barrierless thermochemical methane dissociation, an electrochemical oxidation pathway is likely competitive at high overpotentials. The unprecedented current densities of ∼10 mA/cm2 for HCOOH and ∼16 mA/cm2 for CH3OH, along with these insights on ambient MOR, will enable the development of highly efficient electrochemical systems for the utilization of CH4.