Microemulsion method for the synthesis of Pt/CNTs and Pd/CNTs and their electrocatalytic activities for ethanol oxidation reactions

For diversifying Pt and Pd materials for electro-oxidation reactions of alcohols, carbon nanotube (CNT)-supported Pd and Pt nanoparticles were prepared by the microemulsion method. This microemulsion method is much milder than the previously reported high temperature reduction methods. Even at room temperature, Pd supported CNTs could be prepared, and crystalline Pt/CNTs were obtained at 75 °C. CTAB and chloroform were used for the phase transfer of CNTs, followed by the formation of metal NPs on the surface of CNTs. The zone axis of ⟨110⟩ was broadly observed in both CNT-supported Pt and Pd NPs, while twin structures were identified only in supported Pd NPs. In ethanol oxidation reactions in alkaline medium, CNT-supported Pd NPs, which were prepared at 75 °C, display the best catalytic activities. While unsupported Pt NPs show excellent CO tolerance with the ratio of the maximum current density of the forward and backward scans being 1.60, all the CNT-supported NPs show relatively good CO tolerance with the ratio ranging from 1.06 to 1.25, compared to 0.321 in unsupported Pd NPs.