A Miniature glucose/O2 biofuel cell with single-walled carbon nanotubes-modified carbon fiber microelectrodes as the substrate

This study demonstrates a new kind of miniature glucose/O₂ biofuel cells (BFCs) based on carbon fiber microelectrodes (CFMEs) modified with single-walled carbon nanotubes (SWNTs). SWNTs are used as a support both for stably confining the electrocatalyst (i.e., methylene green, MG) for the oxidation of NADH and the anodic biocatalyst (i.e., NAD⁺-dependent glucose dehydrogenase, GDH) for the oxidation of glucose and for efficiently facilitating direct electrochemistry of the cathodic biocatalyst (i.e., laccase) for the O₂ reduction. The prepared micro-sized GDH-based bioanode and laccase-based biocathode exhibit good bioelectrocatalytic activity toward the oxidation of glucose and the reduction of oxygen, respectively. In 0.10 M phosphate buffer containing 10 mM NAD⁺ and 45 mM glucose under ambient air, the power density of the assembled miniature compartment-less glucose/O₂ BFC reaches 58 μW cm⁻² at 0.40 V. The stability of the miniature glucose/O₂ BFC is also evaluated.