Electrodeposition of highly alloyed quaternary PtPdRuOs catalyst with highly ordered nanostructure

Introducing palladium to traditional platinum-based alloy electrocatalysts offers a novel approach to develop highly efficient anode electrocatalysts for direct methanol fuel cells. In this communication, we report the preparation of thin-wall mesoporous quaternary PtPdRuOs alloy catalyst via electrochemical co-reduction of their chloride precursors all dissolved in aqueous domains of the liquid crystalline phases of an oligoethylene oxide surfactant. Scanning electron micrographs (SEM) reveal that the deposit is composed of uniform nanospheres with an average diameter of around 120 nm and the average mole composition of the metal elements is Pt37Pd33Ru22Os10. Transmission electron micrographs (TEM) disclose that the nanospheres have an ordered nanostructure which is characterized by periodic pores of 3.6 ± 0.4 nm in diameter separated by walls of 2.4 ± 0.4 nm in thickness. X-ray diffraction studies signal a highly alloying degree for the four metal components in the deposit. The specific electrochemical surface area of the nanostructured powder assessed using underpotential deposited Cu stripping technique is as high as 105 m2 g–1, much higher than that of unsupported precious metal catalysts prepared using standard techniques. These characters suggest that the quaternary PtPdRuOs alloy materials with high surface area and thin-wall mesoporous structure would be a novel class of promising electrocatalysts for direct methanol fuel cells.