Synergistic Iron-Molybdenum Effects for Selective Electrocatalytic Reduction of Nitrite to Nitric Oxide.

We report an efficient bimetallic Mo(IV)Fe(II) electrocatalyst that achieves highly selective nitrite-to-NO reduction. This catalyst demonstrates exceptional performance, with a record turnover frequency (TOF) of ∼10³ s^-1 and a Faradaic efficiency of 93.8%. Mechanistic studies integrating experimental and DFT analyses reveal that the Mo(IV) center preferentially binds NO over the Fe(II) site, preventing the catalytic cycle from terminating at a stable ferrous nitrosyl species. The synergistic interplay between the Fe and Mo centers enhances nitrite dynamic coordination and facilitates reductive N-O bond cleavage, highlighting the critical role of bimetallic synergism in lowering energy barriers and driving demanding exergonic reaction steps involving electron and proton transfer.