Biological Production of Hydrogen

Abstract

Decrease of greenhouse gases like CO2 has become a key challenge for human kind and the study of the electrocatalytic properties of CO2-reducing enzymes such as formate dehydrogenases is of importance for this goal. In this work we study the covalent bonding of Desulfovibrio vulgaris Hildenborough FdhAB formate dehydrogenase to chemically modified gold and low-density graphite electrodes, using electrostatic interactions for favoring oriented immobilization of the enzyme.Electrochemical measurements show both bioelectrocatalytic oxidation of formate and reduction of CO2 by direct electron transfer. Atomic force microscopy and quartz crystal microbalance characterization, as well as comparison of direct and mediated electrocatalysis, suggest that a compact layer of formate dehydrogenase was anchored to the electrode surface with some crosslinked aggregates. Furthermore, operational stability for CO2 electroreduction to formate by direct electron transfer is shown with approximately 100% faradaic yield.