Carbon nanotubes – PEI – Formate dehydrogenase nano-biointerface for the specific bioelectrochemical reduction of CO2 to formate

Reduction of extensive CO2 emissions is one of the key challenges that our society must overcome in order to minimize the effects of global warming and climate change. In this respect, electrochemical reduction of CO2 via redox enzymes is believed to be a promising route to minimize global CO2 concentrations, as they specifically catalyze the selective CO2 reduction in a reversible way at low potentials and mild conditions. In this work, we describe the effective anchoring of the enzyme Desulfovibrio vulgaris Hildenborough FdhAB formate dehydrogenase using electrostatic interactions favoring oriented immobilization, to the surface of MWCNTs-modified low density graphite electrodes with subsequent protection of the enzyme with polyethyleneimine (PEI) polymer. The synergistic effect of MWCNTs and PEI has been studied. High catalytic current densities, up to −230 μA cm−2, as well as a high operational stability of 11 h of continuous long-term measurements, were achieved.