Abstract: Membrane electrolyte assembly (MEA) which is the key component for proton exchange membrane fuel cell (PEMFC) is prepared with 40% Pt/C by catalyst coated membrane (CCM) technique. The main aim of this study is to optimize the performance of fuel cell through change the ratio of Pt/C catalyst to Nafion for the MEA and ratio of PTFE to carbon powder for gas diffusion layer. Furthermore, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques are used to characterize the electrochemical properties of fuel cell. It is found that the optimum ratio of 40%Pt/C to Nafion is 3:1 and the corresponding active surface area of MEA is the highest and the ohmic resistance and charge resistance are the lowest compared to the one in other ratio of catalyst to Nafion. The optimal loading of carbon powder is 2 mg/cm2 and the optimal ratio of polytet rafluoroethylene (PTFE) to carbon powder in the gas diffusion layer is 3:7.

Key words: Cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS), Mass fraction of carbon powder, Membrane electrolyte assembly (MEA), Pt/C catalyst