Understanding and controlling nanoporosity evolution for improving the stability of bimetallic fuel cell catalysts
by Lin Gan, Marc Heggen, Peter Strasser and Rachel O'Malley
Nanoporosity is a frequently reported phenomenon in bimetallic particle ensembles used as electrocatalysts for the oxygen reduction reaction in fuel cells. It is generally considered a favorable characteristic, because it increases the catalytically active surface area.
Using aberration corrected scanning transmission electron microscopy and electron energy loss spectroscopy, we analyzed the composition, nanoporosity and atomic-scale fine structures before and after an electrochemical stability test on a PtNi nanoparticle catalyst. We uncovered that nanoporosity formation is intrinsically tied to a drastic dissolution of Ni and, as a result of this, a rapid drop in intrinsic catalytic activity during operation, translating into severe catalyst performance degradation.
Lin Gan, Marc Heggen, Peter Strasser and Rachel O'Malley: Understanding and controlling nanoporosity evolution for improving the stability of bimetallic fuel cell catalysts, Nano Letters 13 (2013) 1131-1138.