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, ΓB12=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. Nature‐for‐nature: A naturally occurring and eco‐friendly cobalt complex, cyanocobalamin (vitamin B12)‐modified graphene oxide has been identified for the first time as an efficient electrocatalyst for CO2‐to‐CO conversion in aqueous solution.