Glucose oxidase nanotube-based enzymatic biofuel cells with improved laccase biocathodes

Glucose/O₂ biofuel cells (BFCs) with an improved power density and stability were developed, using glucose oxidase (GOD) nanotubes with polypyrrole (PPy)-carbon nanotubes (CNTs)-GOD layers deposited on their surface as an anode and a PPy-laccase-2,2′-azinobis (3-ethylbenzothiazoline-6- sulfonate) diammonium salt (ABTS) film type cathode. The GOD nanotubes were fabricated within the nanopores of an anodized aluminum oxide membrane using a template-assisted layer-by-layer deposition method. These BFCs exhibited a higher volumetric power than the best performance reported previously; this was likely due to an increase in enzyme loading of GOD nanotubes and improved electrochemical properties of the PPy-CNTs-GOD layers. The stability of BFCs was closely related to the leakage of ABTS from the cathode. When the leakage of ABTS was suppressed, the power density of BFCs was nearly unchanged for at least 8 days under physiological conditions.