Immobilized glucose oxidase biofuel cell anode by MWCNTs, ferrocene, and polyethylenimine: Electrochemical performance

Ferrocene-functionalized polyethylenimine and multiwalled carbon nanotubes were attached covalently by glutaraldehyde onto a carbon cloth to develop an immobilized enzyme (glucose oxidase) electrode for biofuel cell applications. Developed enzymatic anode was characterized by electrochemical methods to determine electrochemical performance. Anodic open-circuit potential was measured as within 0–20 mV range. Cyclic voltammetry showed anodic peak for glucose oxidation around 400–600 mV (vs. sat. Ag/AgCl) varying with scan rate. An enzyme fuel cell with 2.5 mg/cm² glucose oxidase-loaded bioanode and 0.70 mg/cm² Pt-loaded cathode attached to Nafion™ 115 membrane has provided around 2.5 mA/cm² current density at short-circuit conditions. Enzymatic kinetic parameters of prepared anode were determined by electrochemical methods that surprisingly indicated less K_M (i.e., better substrate affinity) than that of determined by conventional enzymatic methods. Enzymatic stability determined by electrochemical methods moreover indicated longer enzyme half-life.