Binder/surfactant-free biocathode with bilirubin oxidase for gas-diffusion-type system

• A gas-diffusion-type electrode without any binders or surfactants was constructed.
• Improvement in the interfacial electron transfer of BOD was realized.
• Improvement in the steady-state catalytic reduction current density was realized.
• We created highly efficient platforms for BOD in DET-type bioelectrocatalysis.

Direct electron transfer (DET)-type bioelectrocatalysis of dioxygen (O2) reduction is an essential process for constructing a biocathode for use in an enzymatic biofuel cell. In this study, a gas-diffusion-type electrode without any binders or surfactants, which are both known to interfere with DET-type bioelectrocatalysis, was constructed. Bilirubin oxidase (BOD), a promising catalyst for DET-type O2 reduction, and water-dispersed multiwalled carbon nanotubes compatible with BOD were used. The electrode displayed high kinetic performance in the DET reaction and large steady-state current density under quiescent conditions. In addition, the electrode provided a platform that was eight times more suitable for BOD than a traditional electrode.

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