Bioelectrocatalysis-based dihydrogen/dioxygen fuel cell operating at physiological pH

Abstract

A biochemical fuel cell was constructed using H₂ as fuel to produce H₂O in the reaction with O₂ at neutral pH and ambient temperature. The cell uses carbon felt as an electrode material for both the anode and the cathode and an anion exchange membrane as a separator. The anodic oxidation of H₂ was accelerated by methyl viologen-mediated electrocatalysis with bacterial cells Desulfoibrio ulgaris (Hildenborough) as catalysts, and the cathodic reduction of O₂ was accelerated by 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate)-mediated electrocatalysis with bilirubin oxidase as a catalyst. The bioelectrocatalytic systems allowed the cell to operate at 1.0 V with current 0.9 mA at an electrode of size 1.5 × 1.5 × 0.1 cm³. The cell voltage attained 1.17 V at open circuit, which is close to the standard electromotive force 1.23 V. The cell voltage–current behavior is interpretable by linear sweep voltammetry using the same electrode system. On this basis, the electrochemistry behind the performance of the biochemical fuel cell is discussed.