Strong dipole-promoted N-O bond hydrogenolysis enables ampere-level electrosynthesis of methylamine

The electrochemical hydrogenolysis of nitromethane (CH₃NO₂) in water provides a sustainable route for accessing methylamine (CH₃NH₂), one of the simplest alkyl amines but the most commonly used bulk chemical. However, ineffective activation of the unactivated N−O σ-bond of the N-methylhydroxylamine (CH₃NHOH) intermediate results in a CH₃NH₂ selectivity below 10%. Here, low-coordinated copper (LC-Cu) is designed to enable the conversion of electrochemical CH₃NO₂-to-CH₃NH₂ with 99% selectivity and 97% Faradaic efficiency at a low potential. A strong dipole moment to CH₃NHOH over LC-Cu induces strong adsorption and an obvious Raman shift of the N‒O σ-bond in CH₃NHOH to the LC-Cu surface at lower potentials, thus promoting N‒O hydrogenolysis. The rate-determining step changes as the pH alters, resulting in a pH-relevant volcano trend of CH₃NO₂-to-CH₃NH₂. The ampere-level production of 1.5 mol of CH₃NH₂, easy purification, gram-scale synthesis of deuterated methylamine and drugs, and hydrogenolysis of other N‒O bonds demonstrate promising potential.