Hydrogen-coverage-dependent Ni active sites govern activity and selectivity in large-current methanol oxidation reaction

The unclear decisive factors make it tricky to realize high activity and selectivity for the methanol oxidation reaction (MOR) at an industrial-level current. Using Ni-based hydroxides as model catalysts, we reveal that Ni sites undergo a progressive dehydrogenation from NiO₂H₂ to low-hydrogen-coverage NiO₂H_1−x species, which serve as the active centers under high current densities. This transformation shifts the rate-determining step from catalyst dehydrogenation (NOR mechanism) to *CH₃O dehydrogenation, while the adsorption behavior of *HCOO dictates product selectivity. Guided by these insights, a Fe-NiCo ternary hydroxide catalyst was rationally designed to modulate intermediate adsorption energetics. The optimized Fe-NiCo-TH catalyst delivers industrially relevant MOR performance, achieving >500 mA cm−2 at 1.47 V, >90% formate selectivity, and excellent long-term durability. This study establishes hydrogen-coverage-dependent active sites as a decisive factor in MOR and provides a mechanistic foundation for designing Ni-based electrocatalysts for coupled hydrogen production.