Enzymatic Anodes for Hydrogen Fuel Cells based on Covalent Attachment of Ni-Fe Hydrogenases and Direct Electron Transfer to SAM-Modified Gold Electrodes

Immobilization of hydrogenases onto electrodes is of great interest for developing biofuel cells that use H-2 as a fuel. In this way, hydrogenases replace Pt as electrocatalyst for oxidizing H-2 in the anode. We have developed a method of covalent bonding of Desulfovibrio gigas Ni-Fe hydrogenase and Desulfovibrio vulgaris Hildenborough Ni-Fe-Se hydrogenase to gold electrodes modified with a self assembled monolayer (SAM) of 4-aminothiophenol for measuring high electrocatalytic currents of H-2-oxidation in the absence of redox mediators. Electrochemical measurements and atomic force microscopy characterization show that direct electron transfer between enzyme and the Au support is due to formation of an organized monolayer of hydrogenase over the SAM-modified surface.