Comparison study of preferential oxidation of CO over nanocrystalline Cu/CeO₂ catalysts synthesized by different preparation methods

Preferential oxidation of carbon monoxide in presence of excess hydrogen is a promising alternative to restrict the CO deposition in the Pt-anode in the practical polymer electrolyte membrane fuel cell application. In the present work, nanocrystalline copper-ceria catalysts have been synthesized by hydrothermal method, wet impregnation method and urea nitrate combustion method. Their characterizations have been carried out by using X-ray diffraction, transmission electron microscopy, X . ray photoelectron spectroscopy- It has been found that Cu²⁺replaced Ce⁴⁺in cerium oxide, creating oxygen vacancy. The formation of more nano-sized CeO₂leads to more oxygen vacancies in CeO₂through the formation of interfacial Cu¹⁺ions, which also enhances the CO oxidation activity. Among the synthesized Cu-CeO₂catalysts, the catalyst prepared by hydrothermal method have shown both CO conversion andC O₂selectivity as 100% towards CO oxidation at 373 K in the presence of excess H₂making this catalyst viable for practical fuel cell application.