Evaluation of the Nafion effect on the methanol oxidation activity in Pt-Ru electrocatalyst by combinatorial electrochemistry

Abstract

The influence of the Nafion ionomer as a proton conductor in the platinum-ruthenium alloy electrocatalyst on the methanol oxidation was investigated using combinatorial electrochemisty method. The most active spot composition of Pt-Ru alloy electrocatalysts on the methanol electro-oxidation was Pt(54.5)Ru(45.5), and the most active spot compositionof Pt-Ru-Nafion alloy electrocatalysts on the methanol electro-oxidation was obtained (Pt/Ru(1/1) : Nafion = 63.6 : 36.4, wt%). The electrochemical properties of the electrodes were compared using cyclic voltammetry, impedance spectrum and performance test of direct methanol fuel cell. When the Nafion was added to the Pt-Ru alloy electrocatalyst, the initial activation potential is decreased about 80mV vs. RHE, and the methanol oxidation activity was increased, co currently and the CO was desorbed at lowerpotential(lower thant 130mV vs. RHE). These results suggest the synergic effect of methanol electrooxidation on nafion-active metal catalysts.