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.