High-power lactate/O2 enzymatic biofuel cell based on carbon cloth electrodes modified with MgO-templated carbon

As lactate is a useful biomarker for evaluating conditions of the body and also has a high theoretical energy density as a fuel, enzymatic biofuel cells (BFCs) that utilize lactate as a fuel have received considerable attention. In this study, we have developed a high-power lactate/O2 BFC that comprises composite electrodes made from carbon cloth as a current collector and MgO-templated porous carbon as an electroenzymatic reaction field and enzyme support. The bioanode contains lactate oxidase as an enzyme and 1-methoxy-5-methylphenazinium methylsulfate as a redox mediator. The biocathode contains bilirubin oxidase as an oxygen reduction electrocatalyst and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) as a mediator. To obtain an efficient gas diffusion biocathode, the hydrophobicity of the carbon cloth is modulated by modification with PTFE. The lactate/O2 BFC shows a maximum power density of 4.3 mW cm−2 at a lactate concentration of 300 mM. This high performance is promising for the development of BFCs for wearable applications. [Display omitted] •A high-power lactate/O2 biofuel cell was developed.•The anodic current reached 57 mA cm−2 at 0.31 V in the presence of 300 mM lactate.•The carbon cloth in the biocathode was treated with PTFE to increase hydrophobicity.•The cathodic current density under O2 conditions was −24 mA cm−2.•The biofuel cell showed a maximum power density of 4.3 mW cm−2 under O2 conditions.