Molybdenum and tungsten promoted carbons for use as catalyst supports in methanol electro-oxidation.
Two types of the molybdenum and tungsten promoted carbons (MWCs) were prepared by the successive impregnation and co-impregnation of molybdenum and tungsten precursors on carbon black with a heat treatment. The resulting MWCs were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical techniques and evaluated as a catalyst support for a Pt catalyst in methanol electro-oxidation. MWC-S, prepared by successive impregnation, showed a well developed carbidic phase with a large portion of tungsten carbide phase. In contrast, MWC-C, prepared by co-impregnation, had a lower amount of carbidic carbon and larger fraction of molybdenum carbide phase. MWCs-supported Pt catalysts showed higher catalytic activities than the Pt catalyst on pure carbon black in both CO oxidation and methanol electro-oxidation. In particular, Pt/MWC-S exhibited the highest performance among the Pt catalysts employed in this work. The high activity of Pt/MWC-S can be attributed to the positive effect of molybdenum-tungsten carbide phase, which promotes the activation of water and the removal of intermediate CO species.
Joo
Ji Bong
JB
School of Chemical and Biological Engineering, Institute of Chemical Process, Seoul National University, Seoul 151-744, Republic of Korea.
Kim
Jongsik
J
Kim
Pil
P
Yi
Jongheop
J