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Development of Sn@Pt Core-Shell Nanostructures Supported on Vulcan and N-Doped Graphene as Nanocatalysts for the Ethylene Glycol Oxidation Reaction

Monday, 1 October 2018
Universal Ballroom (Expo Center)
G. Hernández-Vázquez, S. Dessources (Cinvestav Unidad Saltillo), I. L. Alonso-Lemus (CONACYT. Cinvestav Saltillo), B. Escobar-Morales (Centro de Investigación Científica de Yucatán), E. Reguera (CICATA-Legaria), and F. J. Rodriguez-Varela (Cinvestav Unidad Saltillo)
Direct Ethylene Glycol Fuel Cells (DEGFCs) are an attractive alternative to methanol cells, since ethylene glycol fuel (C2H6O2) is less toxic, generates more electrons during its electro-oxidation reaction and has a higher boiling point, which allows an easier handling and storage. Pt/C nanocatalysts are widely used for the Ethylene Glycol Oxidation Reaction (EGOR). However, Pt is negatively affected by the presence of reaction intermediates produced from the reaction, which are strongly bonded to Pt active sites, poisoning the nanomaterial. In view of this issue, one efficient strategy to enhance the catalytic activity and tolerance of Pt-based anodes is the design of catalysts with the addition of a co-catalyst, either as an alloy or as a core-shell nanostructure. Among the co-catalysts with appropriate physicochemical properties, Sn has been widely used to enhance the performance of Pt. In a core-shell configuration, Sn is typically the core and Pt the shell. When used as core material, Sn atoms modify the electronic and structural properties of Pt. This synergetic effect changes the binding energy of EG and intermediate species on the active sites of Pt, increasing its catalytic activity. In this work, core-shell nanocatalysts based on Sn and Pt supported on Vulcan (Sn@Pt/C) and N-doped graphene (Sn@Pt/NG) have been synthesized by the polyol method. The core-shell nanocatalysts have been tested as anode materials for the EGOR and compared with monometallic Pt/C and Pt/NG in 0.5 mol L-1 H2SO4. Electrochemical characterization by cyclic voltammetry (CV) shows that Sn@Pt/C has a higher catalytic activity than Sn@Pt/NG, Pt/C and Pt/NG for the EGOR. For example, Sn@Pt/C generates mass and specific current densities 1.3 and 3.4 times higher than Pt/C. Sn@Pt/NG also shows higher mass and specific activity than Pt/C at low overpotentials. Moreover, Sn@Pt/C and Sn@Pt/NG oxidize COads at more negative potential than the monometallic nanocatalysts. Meanwhile, the NG support shows a positive metal-support effect, since Pt/NG is more tolerant to COads than Pt/C. In conclusion, Sn@Pt core-shell nanocatalysts are an attractive alternative for the EGOR, due to their higher catalytic activity and tolerance to COads than monometallic Pt.