Enhanced activity of rare earth doped PtRu/C catalysts for methanol electro-oxidation

PtRuRE/C catalysts were prepared through doping the commercial JM PtRu/C catalyst with rare earth (RE = La, Eu, Gd, Y, Sm and Er). The doping was conducted by chemical reduction and sintering treatment methods. The catalysts were characterized by transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the rare earth doping did not significantly change the average size of the JM PtRu/C particles, and modified the PtRu surface with two element states of the metal and oxide. Studies of cyclic voltammetry and chronoamperometry indicated that the electrocatalytic activity of PtRuRE/C catalysts was higher than that of the JM PtRu/C for methanol oxidation (except for PtRuGd/C), generating a decreasing order of PtRuEu/C > PtRuEr/C > PtRuY/C > PtRuSm/C > PtRuLa/C > JM PtRu/C > PtRuGd/C. It has revealed that among the PtRuRE/C catalysts the PtRuEu/C exhibited the best performance. In addition, the reaction process of methanol electrocatalytic oxidation on several catalysts was investigated by in situ FTIR spectroscopy at molecule level. The results demonstrated that the adsorbates derived from methanol dissociative adsorption on the catalysts were the linear-bonded CO (CO(L)), and the CO-tolerance performance of PtRuRE/C catalysts was better than JM PtRu/C. It has revealed also that the electronic effect of rare earth plays an important role in the catalytic performance of PtRuRE/C catalysts for methanol electrooxidation. (C) 2011 Elsevier Ltd. All rights reserved.