Synthesis and Characterization of Pt-Sn Incorporated MCM-41 and Pt Incorporated Sn-SiOsub2/sub Type Mesoporous Catalysts for Direct Ethanol Fuel Cell

In this study, Pt-Sn incorporated mesoporous silicate materials were synthesized and characterized, and their activities in ethanol electro-oxidation reaction were tested by cyclic voltammetry. Two groups of catalysts were prepared. In the first group, PtCM-41 and Pt-SnCM-41 were prepared by impregnation of Pt and Sn onto MCM-41 support, which was synthesized by one-pot hydrothermal synthesis method. We adjusted the Pt/Sn molar ratio of 2 in the synthesis solution, and the Pt-Sn alloy formation was recognized beside large platinum particles for Pt-SnCM-41. In the second group of catalysts, Sn-SiO2 was prepared by one-pot hydrothermal synthesis procedure with a Sn/Si molar ratio of 0.014 and was used as support material for Pt. Tin oxide phase was well dispersed through silicate structure and only large Pt particles were found in the XRD analysis of Ptn-SiO2, in which the Pt/Sn ratio was 2. In order to see the effect of Pt/Sn molar ratio on the structural and catalytic activity of the catalyst, Ptn-SiO2(3:2) was prepared by changing the Pt/Sn ratio to 3/2 and obtaining smaller particles for the later one. After electrochemical activity tests in 0.5M H2SO4 and 0.5M H2SO4 + 0.5M C2H5OH electrolyte environments, it was seen that PtCM-41, Pt-SnCM-41, Pt-n-SiO2(3:2) and Ptn-SiO2, exhibit different ethanol electro-oxidation behavior, which is assumed to be due to different pore and crystalline size. Sn-SiO2 supported Pt showed the highest oxidation currents after 0.6V vs. RHE. An ethanol oxidation behavior of Ptn-SiO2(3:2) and polycrystalline Pt was very close at 0.6V vs. RHE.