Direct Partial Oxidation of Methane to Methanol at Plasma-Catalyst-Liquid Interfaces

The direct and selective partial oxidation of methane to methanol remains a major challenge in chemistry. Here, we introduce engineered plasma-catalyst-liquid interfaces that enable a one-step, ambient pressure, and room temperature pathway for selective methane oxidation. By integrating a CuO-infused porous glass-frit with a nonthermal methane plasma at an aqueous interface, we demonstrate the importance of mass transfer of plasma-activated species to the catalyst surface in controlling this reaction. Through systematic studies of reaction mass transport and modifying the electron energy distribution function of the plasma environment, we show an optimized liquid-phase methanol selectivity of 96.8 ± 0.6% with a simultaneous production rate of 51.8 ± 1.5 mmol gCuO⁻¹ hr⁻¹. This work demonstrates the importance of leveraging catalytic interfaces to control oxygenate selectivity at plasma-catalyst-liquid interfaces for the selective activation of small molecules.