Metal-defect pairs for near-stoichiometric electrocatalytic C–N coupling

ABSTRACT Geminal-site catalysts (GSCs) are prospective candidates for fulfilling the goal of aqueous electrochemical reductive cross-coupling reactions (ERCR) at near-stoichiometric yields. Nevertheless, a problem lies in the lack of a synthetic route for GSCs with few single sites. Here we report a defect-accompanying strategy for synthesizing GSCs containing metal-defect catalytic pairs (M-D GSCs), meaning that Fe-D GSCs can realize the electrochemical synthesis of cyclohexanone oximes (CHOs) from high concentrations (0.5 M) of nitrites (NO2−) and cyclohexanone (CYC) at near-stoichiometric yields (the Faradic efficiency or yieldC/N: 91.3%). Multiple in-/ex-situ characterizations demonstrated that metal-citrate complexes were converted to metal-defect catalytic pairs via the liberation of gaseous carbon/nitrogen species during pyrolysis. Furthermore, we developed an innovative cathodic oxime-alkali process, where high concentration NaNO2 and CYC can be electrochemically converted to high-purity products including NaOH and CHO. This work showcases the enormous potential of M-D GSCs in achieving near-stoichiometric conversion for ERCR reactions.