High-Temperature Electrochemical Characterization of Ru Core Pt Shell Fuel Cell Catalyst

The electrooxidation of methanol was studied at elevated temperature and pressure by cyclic voltammetry and constant potential experiments at real fuel cell electrocatalysts. Ruthenium core and platinum shell nanoparticles were synthesized by a sequential polyol route, and characterized electrochemically by CO stripping at room temperature to quickly confirm the structure of the synthesized coreshell structure as compared to pure commercial Pt/C and PtRu/C alloy catalysts. A significant promotional effect of Pt decorated Ru cores in the methanol oxidation was found at elevated temperatures and rather high-electrode potentials. A negative potential shift of the methanol oxidation peak is observed for the Ru@Pt/C coreshell catalyst at moderate temperatures, while a significant shift to positive potentials of the methanol oxidation peak occurs for Pt/C catalysts. The onset potential for methanol oxidation is lowered some 200 mV from room temperature and up to 120 degrees C for all electrocatalysts, indicating that it is the thermal activity of water adsorption that dictates the onset potential. Direct methanol fuel cell experiments showed only small performance differences between Ru@Pt/C and Pt/C anode electrocatalysts, suggesting the necessity of render possible the formation of surface oxygen species at lower electrode potentials.