Fabrication of carbon nanotubes and charge transfer complex-based electrodes for a glucose/oxygen biofuel cell

Enzymatic electrodes for glucose biosensors and glucose/oxygen biofuel cells were prepared by the sequential coating of carbon nanotube (CNT), ZnO nano rods, charge transfer complex based on tetracyanoquinodimethane and tetrathiafulvalene (TCNQ-TTF), and glucose oxidase. Among the prepared electrodes (TCNQ-TTF/GOx/Nafion, ZnO/GOx/Nafion, CNT/GOx/Nafion, ZnO/TCNQ-TTF/GOx/Nafion, and CNT/TCNQ-TTF/GOx/Nafion), the CNT/TCNQ-TTF/GOx/Nafion electrode exhibited the best electrochemical performance. It was found that the TCNQ-TTF electron mediator played a critical role in the electron transfer for the active sites of GOx to the electrode and the peak current increased by 150% due to the presence of CNTs. The peak current of the CNT/TCNQ-TTF/GOx/Nafion electrode increased linearly with the increase of glucose concentration in the range of 0-15 mM. The CNT/TCNQ-TTF/GOx/Nafion electrode was integrated with a bilirubin oxidase-immobilized cathode for biofuel cell applications. The maximum power density at glucose concentrations of 20 and 200 mM were 8.1 and 17.8 microW/cm2, respectively. The result of this study indicates that the CNT/Fc/GOx/CHI electrode can be applied in the development of biofuel cells and biosensors.