Performance Assessment of a Perfluorosulfonic Acid-type Membrane (i. e. Nafion (TM) 115) for an Enzymatic Fuel Cell

A high power enzymatic fuel-cell was anticipated by using a recently developed glucose oxidase (GOx) immobilized bio-anode, a conventional platinum-carbon based cathode and a popular high performance 125 mu-thick perfluorosulfonic acid-type proton exchange membrane (i. e. Nafion (R) 115). Unexpected current density decay from 2.13 mA cm(-2) to 0.28 mA cm(-2) was observed within 2 hours. Polarization measurements and AC impedance analysis indicated that loss of performance was linked to the membrane behavior. Ion exchange between buffer solution and membrane was perceived as the main cause for the fast performance loss. Saturation of the membrane with the cation in the buffer solution diminished proton transfer needed for cathode reaction. Charge transfer resistances, obtained from AC impedance data, increased with time substantially due to cation exchange within membrane. Replacement of membrane with the same enzyme electrode and cathode has resulted 100 % current density recovery on the fuel cell performance. It was concluded that a membrane, not affected by the buffer cations, was required for successful enzymatic fuel cell applications.