An Air‐breathing Carbon Cloth‐based Screen‐printed Electrode for Applications in Enzymatic Biofuel Cells

We report a prototype air‐breathing carbon cloth‐based electrode that was fabricated starting from a commercially available screen‐printed electrode equipped with a transparent ITO working electrode (DropSens, ref. ITO10). The fabrication of the air‐breathing electrodes is straightforward, shows satisfactory reproducibility and a good electrochemical response as evaluated by means of [Fe(CN) 6 ] 3−/4− voltammetry. The gas‐diffusion electrodes were successfully modified with the O 2 reducing enzyme bilirubin oxidase from Myrothecium verrucaria in a direct electron transfer regime. The enzyme modified electrodes showed a remarkable high current density for O 2 reduction in passive air‐breathing mode of up to 5 mA cm −2 . Moreover, the enzyme modified electrodes were applied as O 2 reducing biocathodes in a glucose/air enzymatic biofuel cell in combination with a high current density glucose oxidase/redox polymer bioanode. The biofuel cell provides a high maximum power density of (0.34±0.02) mW cm −2 at 0.25 V. The straightforward design, low cost and the high reproducibility of these electrodes are considered as basis for standardized measurements under gas‐breathing conditions and for high throughput screening of gas converting (bio‐)catalysts.