Fabrication of optimally configured layers of SWCNTs, gold nanoparticles, and glucose oxidase on ITO electrodes for high-power enzymatic biofuel cells

We designed an enzymatic biofuel cell (EFC) that utilizes indium tin oxide (ITO) electrodes, and sequential deposition of single-walled carbon nanotube (SWCNT) and gold nanoparticle (AuNP) layers on the electrodes to enhance their electron transfer. Cyclic voltammograms of the SWCNT-modified ITO electrodes showed higher peak currents compared to those of the bare ITO electrodes. Immobilization of glucose oxidase (GOD) on SWCNT-modi-fied ITO electrodes increased their electron transfer resistance by a factor of ten, which could be mitigated by incorporating an AuNP layer between the GOD and SWCNT layers. The single-layer GOD generated higher current than the doubled-layer GOD, with higher specific activity. The assembled EFC featured SWCNT-modified ITO electrodes with sequential layers of immobilized AuNPs and GOD (anode), and with a single layer of immobilized bilirubin oxidase (BOD) (cathode). The cathode performance was further improved by the presence of AuNPs between the BOD and SWCNTs on cathode. The enhanced electron transfer kinetics and enzymatic activity observed for SWCNT/AuNP-modified ITO electrodes resulted in a maximum power density of 38.2±2.0 µW/cm 2 at 0.57±0.03 V of a cell voltage.