Modification of a Pt surface by spontaneous Sn deposition for electrocatalytic applications |
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Authors: | G?Stalnionis L?Tama?auskait?-Tama?iūnait? V?Pautienien? A?Sudavi?ius Email author" target="_blank">Z?JusysEmail author |
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Institution: | (1) Institute of Chemistry, A. Gotauto 9, 2600 Vilnius, Lithuania;(2) Present address: Department of Surface Chemistry and Catalysis, University of Ulm, Albert-Einstein-Allee 47, 89069 Ulm, Germany |
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Abstract: | In the present communication we explored a simple dip-coating method for spontaneous (without applying an external current or additional reducing agents) modification of Pt surface by both tin oxy-species and tin metal based on hydrolysis of tin chloride complex and autocatalytic (electroless) deposition of tin for fabrication of the fuel cell catalysts with improved CO tolerance. It consisted of (i) Pt immersion into SnCl2/HCl solution under open-circuit conditions; (ii) subsequent rinsing of the surface by pure water. The resulting Sn-modified Pt surfaces were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). Two types of tin species, namely, tin oxide/hydroxide species and metallic tin were identified at Pt surface. Tin oxide/hydroxide species were assumed to be derived as a result of Sn(II) chloride complex hydrolysis, while tin metal particles were most likely deposited spontaneously on Pt surface due to disproportionation of Sn(II) to Sn(IV) and metallic tin, competing with dissolution of the Sn deposit in strongly acidic medium. Modifying tin species show a satisfactory stability in 0.5-M H2SO4 solution at potentials relevant to low-temperature fuel cell operating conditions (below 0.6 V vs. a standard hydrogen electrode, SHE). |
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Keywords: | Spontaneous deposition Surface modification Tin Pt AFM XPS Electrocatalysis |
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