Optimization of Enzyme-Reconstituted Electrodes in Enzymatic Biofuel Cell for Low Power Applications

An enzymatic biofuel cell (EFC) uses enzymes as a catalyst to oxidize its fuel, instead of precious metals like Platinum as in a conventional hydrogen fuel cell. Here to generate electricity chemical energy stored say in glucose is converted into electricity. Enzymatic oxidation from complex sugar is carried out by glucose selective enzymes such as gluco oxidase (Gox). In this cell the cathode was an air breathing catalysed structure. These reactions are highly enzyme specific and occur at relatively mild conditions (Neutral pH and ambient temperature). It is necessary to thus to fabricate enzyme reconstituted electrode for the Membrane Electrode Assemble (MEA). The cell features are a 3-D meso/micro porous carbon electrode, for high surface area, electrode structure immobilization of the enzyme and electron mediators, Perfluro sulphonic acid membrane to separate the potential developed between the enzymatic activity and the electron acceptor and to facilitate ion transfer, Perspex glass cell structure, Au coated SS 316 micro mesh, as current collectors. The electrochemical characteristics of EFC were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The achieved power density is still below theoretical value. A cell potential of around 0.5 V for 50 hours was achieved. The EFC was optimized for enzyme loading; conductive loss minimization, both electronic and ionic, direct charge transfer for improving charge transfer efficiency, and pore channel and size profile. Low powers of 2.5 micro watts were obtained in the 5 cm2 cell.