Preparation and characterization of PT nanocatalysts supported by thiourea-treated GO nanoparticles : the application to anodic process of DMFC

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2017

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Karaosmanoğlu, Toprak Seda

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In this thesis, Pt / graphene oxide (Pt / GO), Pt / reduced GO (Pt / 24 h thiourea-treated GO), Pt / 20 min thiourea-treated GO, Pt/ 2 h thiourea-treated GO, and Pt / 5 h thiourea-treated GO nanocatalysts were prepared for methanol oxidation reaction (MOR). The last three ones were synthesized for the first time. They were characterized by FTIR, UV-Vis spectroscopy, acid-base back titration, XRD, XPS, TEM and ICP-MS techniques. Their electrochemical properties and performances toward methanol oxidation reaction were defined by cyclic voltammetry (CV). FTIR studies indicated thiourea attachment on the surface of GO at the beginning of the treatment, and the reduction of GO in the longer treatment duration. Acid-base back titration exhibited the decrease in carboxyl and hydroxyl functional groups in consistence with FTIR results. XRD data demonstrated that all the prepared catalysts contain face-centered-cubic platinum nanoparticles in an average size of 3-4 nm. TEM images also confirmed this result. XPS analysis revealed that platinum exists in three different oxidation states, Pt(0), Pt(II), Pt(IV) in different ratios in each nanocatalysts. Electrochemical studies displayed that Pt / 20 min thiourea-treated GO has the highest performance toward methanol oxidation reaction (3.6 times higher than that of commercial E-TEK Pt / Vulcan XC-72 catalyst) due to its highest platinum utility (~94%), roughness factor (256), chemical (~80 m2 / g Pt) and electrochemical surface area ( ~ 75 m2 / g Pt).

Subject Keywords

Methanol., Platinum., Fuel cells., Nanoparticles., Pollution prevention.

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http://etd.lib.metu.edu.tr/upload/12621439/index.pdf
https://hdl.handle.net/11511/26808

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

T. S. Karaosmanoğlu, “Preparation and characterization of PT nanocatalysts supported by thiourea-treated GO nanoparticles : the application to anodic process of DMFC,” M.S. - Master of Science, Middle East Technical University, 2017.