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

Abstract

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 μ‐thick perfluorosulfonic acid‐type proton exchange membrane (i. e. Nafion® 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.

Development of Reasonably Stable Chitosan Based Proton Exchange Membranes for a Glucose Oxidase Based Enzymatic Biofuel Cell

“…In our previous studies, the immobilized GOx bio‐anode having relatively high current density underperformed when it was integrated with the popular perfluorosulfonic acid‐type membrane (i. e. Nafion® 115). A fast current density performance decay (from 2.13 mA cm −2 to 0.28 mA cm −2 within 2 hours) was observed and this behavior was explained by perfluorosulfonic acid‐type membranes proton transport mechanism that was inhibited by the other cations if they are in the reaction medium .…”

“…Therefore, many studies were performed for enzyme electrode development to increase performance [35][36][37][38][39][40][41][42][43]. One the other hand, one of the important challenges for the enzymatic biofuel cell applications is membrane development for proton transfer since popular fuel cell membranes (i. e. perfluorosulfonic acid type membranes like Nafion ® ) are found as not effective because of cation inhibition [6,[18][19]. It was observed clearly from Figure 9 that chitosan membranes could be an effective proton transfer membrane alternative for enzymatic biofuel cells.…”

“…However, unanticipated current density falloff was observed. Investigation with electro impedance spectroscopy (EIS) indicated that the Nafion membrane cation exchange behavior as explained above enabled such performance decay . In this study, reasonably stable proton exchange membranes were developed by using chitosan.…”

Assessment of Glucose Oxidase Based Enzymatic Fuel Cells Integrated With Newly Developed Chitosan Membranes by Electrochemical Impedance Spectroscopy

“…Proton transfer ability of a membrane and electron transport properties of electrodes are of the utmost important parameters for preparing enzymatic fuel cells. However, there were publications reporting difficulties for biofuel cells operation with such membranes due to interferences of other cations on proton transfer mechanism . Rapid current density decay of enzyme fuel cells with such membranes (i. e. Nafion TM ) in several hours of operation was linked to inhibition of proton transfer by sodium, lithium and ammonium cations of phosphate buffers .…”

“…In this study, considering the current enzymatic fuel cell literature, noticeably stable and comparatively high power biofuel cells were developed. Newly developed immobilized glucose oxidase anode and chitosan membranes were combined with a Pt−C catalyzed cathode and serpentine flow‐channel bearing graphite plates to produce state of the art performance . A stack of 5‐cells was successfully integrated to reach 1.5 V potential to run some portable devices (i. e. a calculator, step motor, LED).…”