Methanol oxidation on Pt/CeO₂-C electrocatalyst prepared by microwave-assisted ethylene glycol process

Pt/C and Pt/CeO₂-C catalysts with different CeO₂ contents were prepared by microwave-assisted polyol process and characterized by energy dispersive analysis of X-ray (EDAX), X-ray diffraction (XRD), elemental mapping by X-ray energy dispersive spectroscopy (XEDS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) in this study. Their electrochemical activities and stabilities for methanol electrooxidation were evaluated by cyclic voltammetry, amperometric i-t, electrochemical impedance spectroscopy (EIS), and continued cyclic voltammograms cycles. The results show that the stability of the mixture support with Vulcan XC-72 carbon black and homemade CeO₂ nanomaterial is evidently enhanced in comparison with that of single carbon black, which results from anti-corrosion property of CeO₂ and the interaction between CeO₂ and XC-72 carbon black. And the appropriate content CeO₂ may significantly improve the dispersion of Pt nanoparticles on surface of the mixture support. Too much content CeO₂ may lead to the agglomeration of Pt nanoparticles. The optimal weight ratio of CeO₂ is 20wt.% in Pt/CeO₂-C catalyst with narrower particle size distribution and better dispersion on surface of the mixture support, which exhibits the best activity and stability for methanol electrooxidation among all the samples. The reason for the increased activity and stability is ascribed to the promotion of CO_ads electrooxidation reaction kinetics by CeO₂, the stability of the CeO₂-C mixture support in acidic media, as well as the improvement of CeO₂ for the dispersion of Pt nanoparticles. The addition of CeO₂ into carbon black as a mixture support also can improve the hydrophilicity and wettability of carbon, and this particularity was fully made use of to achieve the Pt deposition on the contact interface of CeO₂ and carbon black smoothly, avoiding the addition of other polymer conductive electrolyte or surfactant.