Development of PtRu-CeO₂/C anode electrocatalyst for direct methanol fuel cells

Ceria (CeO₂)-modified PtRu/C catalysts with different compositions of Ru and CeO₂, viz. PtRu_0.9(CeO₂)_0.1/C, PtRu_0.7(CeO₂)_0.3/C and PtRu_0.5(CeO₂)_0.5/C and unmodified PtRu/C catalyst were synthesized by the sodium borohydride reduction method. Transmission electron microscopic results indicated that the lower concentrated CeO₂-modified PtRu/C catalysts had almost a similar morphological structure (well-dispersed particles with size around 2.3-2.5 nm) with that of the unmodified PtRu/C catalyst. X-ray diffraction and X-ray photoelectron spectroscopy analyses indicated the formation of PtRu alloy and presence of CeO₂ in an amorphous form with a mixed oxidation states (Ce³⁺-Ce⁴⁺). Electro-catalytic activity of these catalysts for methanol oxidation was investigated by linear sweep voltammetry and chronoamperometry and it was found that the PtRu_0.7(CeO₂)_0.3/C catalyst yielded the higher methanol oxidation current than did the unmodified PtRu/C catalysts.