Enhanced methane chlorination via RuO<sub>2</sub>-gas convection electrode with in-situ generated dynamical three-phase boundaries.

Abstract

Chloromethane (CH₃Cl) is a crucial chemical intermediate conventionally synthesized under harsh conditions. Electrocatalytic methane (CH₄) chlorination enables a sustainable alternative by utilizing abundant CH₄ and chlor-alkali feedstocks under ambient conditions. However, the high stability and low solubility of CH₄ limit CH₃Cl's production. To address these issues, we develop a hierarchical system integrating catalyst and electrode designs. RuO₂ catalyst is applied for surface adsorbed chlorine (*Cl) generation and CH₄ activation. We also design a gas convection electrode (GCE), achieving a CH₃Cl yield of 547.5 ± 33.4 mmol cm^-2 h^-1 and a 19-fold enhancement in faradaic efficiency compared to gas diffusion electrodes. This enhancement is attributed to efficient *Cl production by RuO₂, coupled with the convection-dominated mass transport and the GCE's in-situ generation of dynamic three-phase boundaries. Here, we demonstrate an efficient catalyst for electrocatalytic CH₄ chlorination and propose a broadly applicable strategy to enhance reaction efficiency involving less soluble gaseous reactants.