Electrocatalytic C─C Bond Formation Via Cyanide Interception of CO₂ Reduction Intermediates

Electrochemical CO₂ reduction offers a sustainable route to convert greenhouse gas into high-value-added chemicals, yet product distributions remain largely limited to simple C₁-C₃ molecules. Here, we report a new reaction in which CO₂ reduction intermediates undergo direct C-C coupling with an external carbon nucleophile under electrochemical conditions. Using cobalt phthalocyanine supported on multi-walled carbon nanotubes (CoPc/MWCNT) as a catalyst, cyanide ions intercept deeply reduced C₁ intermediates to produce glycolonitrile at 4°C with a faradaic efficiency (FE) of up to 6.6%. Combined electrochemical analysis, control experiments, and density functional theory calculations identify *CH₂O as the key coupling intermediate, revealing a C-C coupling mechanism fundamentally different from conventional coupling pathways in CO₂ electroreduction to synthesize C₂₊ compounds. Extending this concept to a three-component reaction involving hydroxylamine (NH₂OH) enables electrocatalytic synthesis of glycine under ambient pressure with a FE of 2.8%. This work establishes a new strategy for constructing complex carbon skeletons directly from CO₂ and external nucleophiles, expanding the synthetic scope of electrochemical carbon conversion.