Mathematical modeling and experimental validation of direct ethanol fuel cell

• Mathematical model predicts DEFC performance well for different anode catalysts.
• Faradaic efficiency decreases with increase in ethanol concentration and current.
• Ethanol crossover decreases with current at ethanol conc ≤1 M and increases ≥2 M.
• To minimize ethanol crossover, ethanol concentration and current should be optimized.

In the present work a one dimensional steady state, mathematical model is developed to analyse the performance of direct ethanol fuel cell (DEFC). The model considers species mass transfer relations for flow channel, gas diffusion layer at the electrodes and multistep bi-functional ethanol oxidation reactions at the anode catalyst layer and oxygen reduction reaction at the cathode catalysts layer. The model takes into account diffusion and convective effects for ethanol transport, hydraulic permeation and diffusion of gases between the electrodes through proton exchange membrane. The model predicted well the current–voltage data of DEFC for different anode catalysts e.g., Pt-Re-Sn/MCN (20:5:15), Pt–Ru/MCN (20:20), Pt-Re-Sn/t-MWCNTs (20:5:15) and Pt-Re-Sn/C (20:5:15). According to the model predictions the increase in ethanol fuel concentration equal and above 2 M leads to higher ethanol crossover rate, parasitic current and mixed potential resulting in decrease in current density and peak power density. However, ethanol crossover levels off or decreases with the increase in current density within ethanol feed concentration of 1 M or less. Thus to maximize DEFC performance or Faradaic efficiency an optimum range current density and ethanol concentration should be used.