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. [ABSTRACT FROM AUTHOR]