Decomposition of Pt–Ru anode catalysts in direct methanol fuel cells

The durability behavior of Pt–Ru anode catalysts under virtual direct methanol fuel cell (DMFC) operating conditions was investigated in the atomic scale using both high-resolution transmission electron microscopy (HR-TEM) and time-of-flight secondary ion mass spectroscopy (TOF-SIMS). We find here the crossover of ruthenium and platinum from the anode to the cathode due to the decomposition of active Pt–Ru anode catalysts. The Ru crossover measured at the cathode increases linearly with performance drop. The Ru contents determined by X-ray photoelectron spectroscopy (XPS) are less than 0.3 atom%. The platinum, newly deposited at the cathode with high performance drop, is formed with the intermixture of defective nanocrystalline (~3 nm) and amorphous structure.