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Pt Nanoparticles Supported on Reduced Graphene Oxide-Carbon Black Hybrids As Robust Electrocatalysts in Polymer Electrolyte Membrane Fuel Cells

Thursday, 5 October 2017: 11:20
National Harbor 2 (Gaylord National Resort and Convention Center)

ABSTRACT WITHDRAWN

Graphene has been utilized as an alternative catalyst support for new generation polymer electrolyte membrane fuel cell (PEMFC) with many outstanding properties which are associated with its 2 dimensional (D) structure [1]. However, restacking of individual graphene layers and the aggregation of platinum (Pt) nanoparticles result in low Pt utilization and low catalytic activity [2,3]. To overcome this problem, herein Pt nanoparticles supported on reduced garphene oxide-carbon black hybrids (rGO-CB) were synthesized by one-pot microwave-assisted synthesis (Figure 1.a). In this one step approach, not only restacking of graphene sheets was avoided by using CB but also Pt nanoparticles impregnated on both graphene and CB. By means of homogenous mixing of GO and CB, 3D CB was placed between the 2D graphene sheets. Therefore, the resultant hybrid possessed higher Pt utilization. In this study, hybrid catalysts were synthesized in varying ratios of GO:CB and optimum GO:CB ratio was selected. Structure of resultant catalysts were confirmed by Raman Spectroscopy, X-ray Diffraction (XRD), X-Ray photoelectron spectroscopy (XPS) and Transmission Electron Microscopy (TEM) techniques. The average diameter of the Pt nanoparticles was about 2-3 nm from TEM micrographs (Figure 1.b). Electrocatalytic activity of prepared catalysts towards fuel cell reactions (HOR and ORR) were investigated by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The hybrid electrocatalyst was exhibited a much higher HOR and ORR catalytic activities than a Pt/rGO and Pt/CB electrocatalyst by enhanced utilization of Pt. Moreover, gas diffusion electrodes and membrane electrode assemblies were fabricated by using synthesized electrocatalysts and tested in the PEMFC. Pt/rGO-CB hybrid delivered a superior PEMFC performance with a maximum power density of 1091 mW cm-2 in comparison to those of Pt/rGO and Pt/CB.

References:

1) A.K. Geim and K.S. Novoselov. Nat Mater, 6,183-91 (2007)

2) L.T. Soo, K.S. Loh, A.B. Abu Bakar Mohamad , W.R.W. Daud, and W.Y.Wong. Appl Catal A, 497, 198–210 (2015)

3) S.H. Cho, H.N. Yang, D.C. Lee, S.H. Park, and W.J. Kim. J Power Sources, 225, 200-6 (2013)