Chiang Mai Journal of Science

In this work, bimetallic Au@Pt core shell catalysts were synthesized using electroless deposition (ED) of Pt on a Au/CeO₂-Al₂O₃ catalyst prepared by strong electrostatic adsorption (SEA). The CeO₂-Al₂O₃ support was prepared by co-precipitation. TEM characterization of Au/CeO₂-Al₂O₃ showed well dispersed particles with an average Au crystalline size of 5-6 nm. In ED preparation, ED bath containing PtCl₆^2- as a Pt precursor, ethylene diamine as a stabilizer and hydrazine as reducing agent successfully deposited Pt on Au particles with the loading of 0.5, 0.8 and 1.2 %wt. Physical adsorption of N₂ confirmed mesoporous materials. TEM-EDS mapping and XPS indicated the core-shell structure of Au@Pt catalysts. Catalytic activities of bimetallic Au@Pt core shell catalysts for CO oxidation reaction were conducted. Catalysts with Pt loading of 0.8 and 1.2%wt completely converted CO to CO₂ at 140^oC and 170^oC for 0.5%Pt loading. Comparison of catalytic activities of monometallic Pt, Au, and bimetallic Pt-Au alloy with Au@Pt core shell were also investigated. Complete CO conversions occurred at 240^oC for both monometallic catalysts and about 10% CO conversion at the same temperature for bimetallic Pt-Au alloy. These results indicated the improvement of catalytic activity of bimetallic core shell structure.  

Keywords: Bimetallic Au-Pt, Strong electrostatic adsorption, Electroless deposition, CO oxidation reaction, PEMFCs.