posted on 2020-09-04, 14:45authored byChen Jia, Karin Ching, Priyank V. Kumar, Chuan Zhao, Naresh Kumar, Xianjue Chen, Biswanath Das
Combining the advantages of homogeneous and heterogeneous catalytic
systems has emerged as a promising strategy for electrochemical CO2 reduction although developing robust, active, product-selective,
and easily available, catalysts remains a major challenge. Herein,
we report the electroreduction of CO2 catalyzed by cobalt
and benzimidazole containing Vitamin B12 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 CO2 to CO at an overpotential of 690 mV with
a CO partial current density (jCO) of
6.24 mA cm–2 and a turnover frequency (TOF) of up
to 28.6 s–1. A higher jCO (13.6 mA cm–2) and TOF (52.4 s–1) 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
CO2 electroreduction.