A single-liquid miniature biofuel cell with boosting power density via gas diffusion bioelectrode
The low solubility of gas molecules in aqueous solution limited the power density output of the enzymatic biofuel cell. Herein, a single-liquid miniature glucose-O2 fuel cell was constructed by using gas diffusion electrode which were prepared by immobilizing of glucose oxidase (GOx) or laccase (Lac) modified porous structured carbon paper (CP). Due to the fast and direct O2 diffusion from air to active sites of the immobilized enzyme through the porous of CP anode/cathode with controlled wettability, the maximum power output density was dramatically increased to 9.64 μW cm-2 at 0.43 V and 53.0 μW cm-2 at 0.45 V for the cell in 5 mM glucose and exposing the cell in air or O2 atmosphere, respectively. Interestingly, the resulting single-liquid cell could harvest power from human serum operating a maximum power density of 49.0 μW cm-2 at 0.2 V. The biofuel cell fabricated by gas diffusion electrode displayed advantages such as high output power density, low cost and high ‘on-chip’ integrability miniaturization, which was great potential for implantable self-powered sensor and envision many future applications.