Physical and morphological characteristics and electrochemical behaviour in PEM fuel cells of PtRu/C catalysts

Platinum-ruthenium catalysts supported on carbon (PtRu/C) have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area analysis (BET), X-ray photoelectron spectroscopy (XPS) and in proton exchange membrane (PEM) fuel cell tests. The results indicate the presence of strong metal-carbon interactions, which hinder the formation of a single-phase face-centered cubic (fcc) PtRu alloy. The particle size of the PtRu/C catalysts was smaller than both carbon-supported platinum (Pt/C) and ruthenium (Ru/C) catalysts. In the bimetallic electrocatalysts the intercrystallite distance decreased with respect to pure Pt and Ru metals. PEM fuel cell tests in H-2/air operation mode revealed a decrease of performance with increasing carbon content of the catalyst, at a fixed Pt loading. In H-2 + 100 ppm CO/air operation mode the maximum performance of the PEM fuel cell was attained at 0.63 atomic fraction Ru.