A composite cathode of biofuel cell based on cross-linked Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate and platinum nanoparticles

Glucose oxidase based enzymatic biofuel cell is the promising technology for implantable medical devices' power supply. It can open up opportunities for the long-term implantation of the medical devices like pacemakers without the necessity for replacement of the batteries. Increasing of the cathode efficiency is one of the issues that should be solved before a practical application of biofuel cells. The high catalytic activity of the cathode provides a significant contribution to the efficiency of biofuel cells operation. The creation of cathodes of implantable biofuel cell with the increased power density could resolve the problem with a slow kinetics of the cathodic oxygen reduction reaction. It is especially urgent in the conditions of implantation in physiological fluids, where the oxygen concentration is relatively low. Enzymes application could be an optimal way to increase an efficiency of the cathodic reaction, but enzymes long-time stability is still in question. Thus, non-organic and synthetic organic catalysts are considered. In this study, a new type of a cathode for enzymatic biofuel cells is presented. This cathode combines two catalysts: inorganic with platinum nanoparticles (PtNPs) and organic in the form of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) cross-linked by poly(ethylene glycol) diglycidyl ether (PEGDE). The received electrodes were investigated by several electrochemical methods: cyclic voltammetry, chronopotentiometry and linear sweep voltammetry method on a rotating disk electrode. It was shown that the combination of PtNPs and PEDOT:PSS provides the maximum cathodic current, due to the fact that both catalysts contribute to the oxygen reduction reaction. The maximum cathodic current was 7.5 mu A for an electrode containing 5 % PEGDE with PtNPs, heat-treated for one hour at 120 degrees C. The electrodes without platinum nanoparticles were also investigated. This research showed that PEDOT:PSS provides a significant contribution to the overall catalytic effect demonstrated by the electrode proposed in the study. Scanning electron microscopy and X-ray fluorescence analysis studies showed that the electrodes with combination of PtNPs and PEDOT:PSS were almost fully covered by catalysts.