Coordination restraint of Rh-Cu diatomic catalyst and C-H bond oxygen insertion for methanol synthesis

Direct oxidation of methane to methanol is valuable, but reactive oxygen species over oxidize methane and lower selectivity. Here we report a Rh-Cu heteronuclear dual atom catalyst on nitrogen doped graphite that separates sites and restrains oxygen intermediates, enabling methanol through oxygen insertion into C-H bonds. An encapsulated pyrolysis strategy yields an Rh-Cu-N6 motif with a Rh-Cu distance of 2.42 Å. Electronic coupling between Rh and Cu induces charge polarization and improves reactant activation. Cu captures active oxygen species, suppressing excessive oxygen insertion and deep oxidation. The catalyst achieves up to 81% methanol selectivity and about threefold higher activity than a single atom Rh catalyst. In situ Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) calculations reveal stable oxygen bridged intermediates, Rh-O-O-Cu and Rh-O-Cu. Rh stabilizes methyl intermediates, while Cu restrains nearby oxygen reactivity and directs oxygen insertion into C-H bonds to form methanol. Turning methane into methanol is valuable, but reactive oxygen often over-oxidizes methane and ruins selectivity. A Rh-Cu dual-atom catalyst separates tasks so oxygen is restrained, boosting methanol selectivity to 81% and tripling activity.