Evolution of the electrocatalytic activity of carbon-supported amorphous platinum-ruthenium-nickel-phosphorous nanoparticles for methanol oxidation

Amorphous metallic nanoparticles hold much promise for use as electrocatalysts, as their surface is rich in low-coordination sites and defects which could act as the electrocatalyt's active sites. In this study, we describe new findings on amorphous platinum-ruthenium-nickel-phosphorous nanoparticles supported on carbon (PtRuNiPa/C) and the comparison between their catalytic activity and the degree of disorder. The nanoscale amorphous structure with different degrees of disorder are probed as a function of surface composition, particle size, and thermal treatment conditions using X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, selected area electron diffraction and electrochemical characterization. The results provide experimental evidence in support of nanoscale long-range disorder, medium-range disorder, and medium-range order evolution dependence on the catalyst synthesis temperature. More importantly, the results of the electrochemical performance investigation show that the amorphous structures with medium-range disorder have not only better catalytic activity, but also better durability for methanol oxidation compared to the long-range disorder and medium-range order structure. These results provide an opportunity for establishing the correlation between the nanoscale amorphous structure and their electrocatalytic activity for methanol oxidation reaction, which could play an important role in developing new high active catalysts for direct methanol fuel cells. (C) 2014 Elsevier B.V. All rights reserved.