Synthesis of New-Electrocatalyst as Pt3Sn by Chemical Reduction Method for Methanol Electro-oxidation

Low temperature direct alcohol fuel cells (DAFCS) are extremely attractive as power sources for transportation, mobile and portable applications because it is not necessary to convert the fuel in a reformer into hydrogen. However, alcohols are very difficult to electro_ oxidized completely and up to now methanol has been considered the most promising fuel, because it is more efficiently oxidized than other alcohols and thus direct methanol fuel cells (DMFCS) have been developed for the portable power market. The methanol oxidation reaction (MOR) by itself is rather slow and requires active catalytic sites for adsorption and oxidation of methanol. Pt or Pt_ based alloys, supported by carbon materials are commonly used catalysts in direct methanol fuel cells (DMFCS) in acidic solution. Polyaniline (PANI) with porous structure and high surface area is a particulary attractive material as catalyst support. In this work, platinum and platinum_ tin catalysts with an atomic ratio Pt/Sn (3:1) supported on Multiwall carbon nanotubes and Vulkan carbon are prepared by a deposition process using NaBH4 as the reducing agent and from this category of materials was used as the anodic electrocatalysts in direct methanol fuel cells. Specificinty structural, morphology and electrochemical behavior synthesized electrocatalysts by methods of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and cyclic voltammetry (CV) are investigated. From the XRD patterns, the Pt(220) peak of the PtSn/C, PtSn/MWCNT catalysts shift slightly to lower 2𝜃 values with increasing Sn compared with that of the Pt/C, Pt/MWCNT catalysts, suggesting the alloy formation. The cyclic voltammetry reveals that PtSn/MWCNT electrocatalyst in methanol oxidation shows a greater oxidation current and a lower onest potential, compared to other electrocatalysts. Then the effect of glassy carbon electrode (GC) surface modification by a thin layer of 13th Annual Electrochemistry Seminar of Iran Materials and Energy Research Center (MERC), 22- 23 Nov, 2017 197 polyaniline is investigated. The results show that in present a thin layer of polyaniline and platinum-tin electrocatalytic particles supported on multiwall carbon nanotube (GC/PANI/Pt-Sn/MWCNT) the oxidation of methanol in aqueous acid media is considerably enhanced. (b) (a) Fig.1. CVS of Pt/MWCNT (a), Pt-Sn/MWCNT in 0.5M CH3OH and 0.1 H2SO4. (b) (a) Fig.2. FESEM images of Pt-Sn/MWCNT (a), Pt/MWCNT(b).