Improvement of Electrochemical Activity of Pt/MWCNT Catalyst for Proton Exchange Membrane Fuel Cell
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Improvement of Electrochemical Activity of Pt/MWCNT Catalyst for Proton Exchange Membrane Fuel Cell Battsengel Baatar, Bayardulam Jamiyansuren, Munkhshur Myakhlai and Baasandorj Myagmarsuren Center for Nanoscience and Nanotechnology and Department of Chemical Technology, School of Chemistry and Chemical Engineering, National University of Mongolia, University Street 1, 14704, Ulaanbaatar, Mongolia ABSTRACT In last years, the carbon nanotubes have been studied as an advanced metal catalyst support for proton exchange membrane fuel cell. This study focuses on the sonochemical treatment of multi walled carbon nanotubes (MWCNTs) as a platinum supporting material for proton exchange membrane fuel cell (PEMFC) by mixture of sulfuric acid and nitric acid and mixture of sulfuric acid and hydrogen peroxide. X-ray diffraction (XRD) and Infrared (IR) spectroscopy were used to characterize the surface of sonochemically treated MWCNT and nanostructured electrocatalyst Pt/MWCNT. According to the experimental results of this work, the surface of MWCNT can be more successfully functionalized with hydroxyl and carboxyl groups after sonochemical treatment by mixture of sulfuric acid and nitric acid. The particle size of prepared Pt -electrocatalyst on MWCNT was determined 3.4 nm by XRD. INTRODUCTION Carbon nanotubes (CNT) have attracted much attention due to their extraordinary electrical, mechanical and structural properties [1]. In recent years, there has been increasing interest in carbon nanotubes as heterogeneous catalyst support. Studies have shown that metal nanoparticles supported on carbon nanotubes may provide much improved catalytic activity [2]. Recently, carbon nanotubes have been proposed as promising support materials for fuel cell catalyst due to their unique characteristics, including high aspect ratio, high electron conductivity, and enhanced mass transport capability [3]. The catalytic activity of the Pt based catalysts is strongly dependent on the composition, structure, morphology, particle size, alloying degree [4,5] and catalyst supports [6,7]. In many of these applications, CNTs have to be surface functionalized [8]. Among various surface functionalization techniques, oxidation is probably the most widely studied. Oxidation of CNTs has been used to remove amorphous carbon for purification purposes [9] and to open CNT ends for metal nanoparticle insertion [10]. Early treatment techniques have involved gas-phase oxidation in air and oxidative plasmas but these techniques have led to an over-oxidation of CNTs, often severely damaging the CNTs and removing the amorphous carbon in addition. Liquid-phase oxidation involves acidic etching with nitric and/or sulfuric acids. Compared to gas-phase oxidation, this method is mild and slow, and can provide a high yield of oxidized CNTs. For an amorphous carbon removal and end opening, oxidation damage to the surface of the CNTs is not desired [11].
Noble metals, such as Pt, Ru or Pt-Ru alloys, supported on carbon materials with high surface area are important electrochem
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