Vitamin B on Graphene for Highly Efficient CO Electroreduction.

Combining the advantages of homogeneous and heterogeneous catalytic systems has emerged as a promising strategy for electrochemical CO reduction although developing robust, active, product-selective, and easily available, catalysts remains a major challenge. Herein, we report the electroreduction of CO catalyzed by cobalt and benzimidazole containing Vitamin B immobilized on the surface of reduced graphene oxide (rGO). This hybrid system with a naturally abundant molecular catalyst produces CO with high selectivity and a constant current density in an aqueous buffer solution (pH 7.2) for over 10 h. A Faradaic efficiency (FE) of 94.5% was obtained for converting CO to CO at an overpotential of 690 mV with a CO partial current density () of 6.24 mA cm and a turnover frequency (TOF) of up to 28.6 s. A higher (13.6 mA cm) and TOF (52.4 s) can be achieved with this system at a higher overpotential (790 mV) without affecting the product selectivity (∼94%) for CO formation. Our experimental findings are corroborated with density functional theory (DFT) studies to understand the influence of the covalently attached and redox-active benzimidazole unit. To the best of our knowledge, this is the first example of naturally abundant vitamin being immobilized on a conductive surface for highly efficient CO electroreduction.