Vitamin B12-Immobilized Graphene Oxide for Efficient Electrocatalytic Carbon Dioxide Reduction Reaction

A naturally occurring water-soluble cobalt-complex cyanocobalamin (Vitamin B12) has been identified as a new and efficient electrocatalyst for the CO₂ -to-CO reduction reaction in aqueous solution. Heterogeneous B12-electrocatalysts prepared by a simple electrochemical immobilization technique on graphene-oxide (GO)-modified glassy carbon and carbon paper (CP) electrodes, without any non-degradable polymer-binders, showed a highly stable and well-defined surface-confined redox peak at E'=-0.138 V vs. RHE with a surface-excess value, Γ_B12 =4.28 nmol cm^-2 . This new electrocatalyst exhibits 93 % Faradaic efficiency for CO₂ -to-CO conversion at an electrolysis potential, -0.882 V vs. RHE (an optimal condition) with a high current density, 29.4 mA cm^-2 and turn-over-frequency value, 5.2 s^-1 , without any surface-fouling problem, in 0.5 m KHCO₃ . In further, it follows an eco-friendly, sustainable and water-based approach with the involvement of biodegradable and non-toxic chemicals/materials like B12, GO and CP.