Direct electron transfer-type dual gas diffusion H2/O2 biofuel cells†
H2/O2 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 H2 oxidation and O2 reduction. The biocathode and the bioanode were coupled to construct a gas diffusion H2/O2 biofuel cell. The dual gas diffusion system allowed the separate supply of gaseous substrates (H2 and O2) 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.