Plasma Electrocatalytic Oxidation of Methane to Methanol

Selective electrocatalytic conversion of methane (CH₄) to methanol (CH₃OH) using renewable electricity under ambient conditions offers an option of interest in providing methane-derived molecules that are readily transported. The high thermodynamic stability and chemical inertness of CH₄ today limit both the productivity and selectivity. Here, we report a hybrid plasma-electrocatalytic system that enables CH₄-to-CH₃OH conversion under ambient conditions. By using plasma to preactivate CH₄, the challenge transits from electrochemical CH₄ oxidation to methyl radical (^•CH₃) conversion. We document the coupling of short-lived CH₃ radicals and adsorbed hydroxyl groups (*OH) at the plasma-catalyst-electrolyte interface. We achieve >90% faradaic efficiency in the electrochemical stage of CH₃ radicals to CH₃OH conversion and a methanol yield on total electrical energy of 60 g_methanol kWh^-1, with plasma energy accounting for 90% of the total electricity. We operated the hybrid plasma-electrocatalytic system for 890 h with an average faradaic efficiency of 86%. This study presents a new radical-based pathway and contributes to activate-and-electrolyze conversion reactions.