화학공학소재연구정보센터
International Journal of Hydrogen Energy, Vol.38, No.35, 15152-15159, 2013
Methanol oxidation on hybrid catalysts: PtRu/C nanostructures promoted with cerium and titanium oxides
Hybrid catalysts comprising of ceramic, metal, and carbon phase were synthesized by incorporating titanium and cerium oxides into PtRu/C commercial catalyst using an in-situ combustion followed by heat treatment at 600 degrees C. The structure dependent electrochemical behavior of as-synthesized and heat-treated materials towards methanol oxidation, carbon dioxide (CO) tolerance and chemical stability was studied by XRD, HRTEM, BET, EDS, cyclic voltammetry, chronoamperometry, and CO-stripping method. As a result of heat treatment, amorphous phase of metal oxides was transformed into a crystalline phase with particle size of about 3-7 nm. Improved methanol oxidation activity of the hybrid catalysts was compared to PtRu/C catalyst as a baseline and explained by the changes in Pt electronic behavior and excess adsorption of OH-ions. When heat-treated at 600 degrees C, CeO2-PtRu/C demonstrated the highest mass activity of 580 mA/mg (similar to 3x that of PtRu/C) compared to TiO2-PtRu/C (394 mA/mg). Heat-treated hybrid catalysts exhibited higher methanol oxidation activity at higher peak potentials than the corresponding as-synthesized materials. However, as-synthesized hybrid catalysts display higher CO-tolerance, lower CO-oxidation onset potentials, and better chemical stability in comparison to corresponding heat-treated catalysts. To explain the difference, a mechanism for ceramic oxide structure dependent electrochemical behavior of the hybrid catalysts is proposed and discussed. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.