Co1Ni single‐atom alloy an efficient heterogeneous catalyst for amines N‐methylation using methanol

Methanol serves as a versatile N‐methylation reagent, functioning as an accessible solvent, sustainable C1 source, and hydrogen donor. However, the conventional N‐methylation pathways utilizing methanol usually require excessive alkali additives to activate the C‐H bond. Here, we develop a TiO2‐supported Co1Ni single‐atom alloy (SAA) catalyst that enables the efficient N‐methylation of 23 types of amines in an additive‐free methanol system, achieving yields over 90% via a methyl formate pathway. Significantly, the SAA demonstrates remarkable proficiency in constructing the N‐CD3 motif using deuterated methanol for the N‐trideuteromethylation reaction of six different amines. Kinetic studies reveal that dehydrogenation of methanol to methyl formate is the rate‐determining step, and that methyl formate acts as the key active intermediate for N‐methylation. Theoretical calculations further demonstrate that the unique adsorption mode of CH3O* intermediate on top of atomically dispersed Co sites in the Co1Ni SAA catalyst endows a lower activation barrier of 0.26 eV toward CH3O* dehydrogenation.