Radical-Electrochemical Coupling Enables Amination of Methane

The selective functionalization of methane under ambient conditions is widely regarded as a holy grail in chemistry, yet remains fundamentally limited not only by the inertness of the C-H bond but also by the transient nature of highly reactive intermediates. Short-lived species are often difficult to preserve and utilize prior to productive coupling, constraining accessible reaction pathways and product selectivity. Here, we establish a reaction framework based on in situ interfacial interception of reactive radicals, enabling the temporal coordination between radical lifetime and subsequent reaction processes. Plasma generates short-lived methyl radicals in immediate proximity to a gas-electrode interface, allowing their direct delivery and capture at the catalytic surface, while the electrochemical interface independently converts ammonia into surface-bound amino intermediates. Their coupling enables selective C-N bond formation. This spatially and temporally coordinated process allows highly reactive radical species to be synchronized with interfacial reaction steps, facilitating their productive utilization. Guided by density functional theory, we identify a nickel-cobalt layered double hydroxide catalyst that promotes interfacial coupling between *CH3 and *NH2 intermediates. The optimized system achieves a Faradaic efficiency of 54% for methylamine at 10 mA cm-2, with a productivity of 201 μmol cm-2 h-1 under ambient conditions. Beyond methane amination, this work demonstrates that coordinating the lifetime and transformation of reactive intermediates provides a generalizable strategy for catalytic control, offering new opportunities for the activation and selective transformation of inert molecules.