Synthesis and characterization of PtRu/C catalysts from microemulsions and emulsions

Abstract

Nanosized PtRu catalysts supported on carbon have been synthesized from inverse microemulsions and emulsions using H₂PtCl₆ (0.025 M)/RuCl₃ (0.025 M)/NaOH (0.025 M) as the aqueous phase, cyclohexane as the oil phase, and NP5 (poly(oxyethylene)₅ nonyl phenol ether) or NP9 (poly(oxyethylene)₉ nonyl phenol) as the surfactant, in the presence of Carbon Black suspended in a mixture of cyclohexane and NP5 + NP9. The titration of 10% HCHO aqueous solution into the inverse microemulsions and emulsions resulted in PtRu/C catalysts, in which the PtRu particles were nanometers in size. The catalysts were characterized by TEM, XRD and XPS and the metal particles were found to inherit the Pt fcc structure with Pt and Ru mostly in the zero valence oxidation states, amidst some Pt(II), Pt(IV) and Ru(IV). The cyclic voltammograms for methanol oxidation on these PtRu/C catalysts showed higher electrocatalytic activities for the two microemulsion derived catalysts than the emulsion-derived electrocatalyst.