| Preparation And Characterization Of Carbon Supported Platinum And Platinum-Second Metal Nanoparticles From Ethylene Glycol Reduction
Polyol process is a versatile chemical sysnthesis technique, which uses the polyols (for example, ethylene glycol, diethylene glycol) to reduce metal salts to metal particles. This technique has successfully been used to prepare non-aggregated nanoparticles from a great variety of inorganic compounds. The polyols in this method often serve as high boiling solvent and reducing agent, as well as stabilizer to control the particles growth and prevent interparticle aggregation.
In this study, Carbon-supported Pt-Co, Pt-Sn, Pt-Cr and Pt catalysts were prepared by polyol and NaBH4 reduction of metal precursors both in single step and in four steps.
The electrochemical performance of the catalysts for methanol electrooxidation in acidic media at room temperature is evaluated and compared with that of a Pt/C catalyst. Electrochemical measurements were carried out by using cyclic voltammetry, lineer sweep voltammetry and chronoamperometry.
The structure and morphology of the as-prepared particles were analyzed using Rigaku D/max-2200 X-Ray diffractometer with CuKα radiation. From X-Ray patterns, crystallite sizes were estimated by using Scherrer equation. As indicated, all XRD patterns show the four main characteristic peaks of the face-centered cubic (fcc) crystalline structure of Pt, namely the planes (1 1 1), (2 0 0), (2 2 0), (3 1 1). No peaks for pure Co, Cr and its oxides were found, but their presence cannot be discarded because they may be present in a very small amount or even in an amorphous form. But XRD patterns of PtSn electrocatalysts have SnO2 peaks at around 34.2o and 52o. As a result, PtSnOx catalyst showed higher catalytic activity for methanol electro-oxidation than PtSn metallic form.
As a conclusion, we have found that catalysts reduced in single step showed much higher catalytic activity towards methanol electrooxidation in anodic reactions.
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