Direct electron transfer-type dual gas diffusion H2/O2 biofuel cells

H-2/O-2 biofuel cells utilizing hydrogenases and multicopper oxidases as bioelectrocatalysts are clean, sustainable, and environmentally friendly power devices. In this study, we constructed a novel gas diffusion bioelectrode with a sheet of waterproof carbon cloth as the electrode base and optimized the hydrophilicity/hydrophobicity of the electrode for both high gas permeability and high direct electron transfer bioelectrocatalytic activity. The electrode exhibited a large current density of about 10 mA cm(-2) in the steady-state for both H-2 oxidation and O-2 reduction. The biocathode and the bioanode were coupled to construct a gas diffusion H-2/O-2 biofuel cell. The dual gas diffusion system allowed the separate supply of gaseous substrates (H-2 and O-2) to the bioanode and biocathode, with consequent suppression of the oxidative inhibition of the hydrogenases. The cell exhibited a maximum power density of 8.4 mW cm(-2) at a cell voltage of 0.7 V under quiescent conditions.