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Displacement reduction routed Au-Pt bimetallic nanoparticles: A highly durable electrocatalyst for methanol oxidation and oxygen reduction

Abstract

In this paper, a new galvanic displacement reduction (GDR) approach was demonstrated for Au-PtNPs synthesis with different Pt:Au compositions in an aqueous medium. The PtNPs were initially synthesized by the reduction of H2PtCl6 using trisodium citrate and sodium borohydride. Addition of various concentrations of HAuCl4 to PtNPs leads to the formation of Au-PtNPs, which follows the GDR between Pt(0) and AuCl4- ions. The formation of Au-PtNPs was monitored by UV-vis spectroscopy by tuning the mole ratio of Pt:Au. HR-TEM images showed that the Au-PtNPs were spherical with 11 nm diameter. HR-TEM, XRD and XPS analysis showed that the formed Au-PtNPs were in the form of core-shell structure. The colloidal Au-PtNPs were then attached on glassy carbon (GC) electrode via 1,6-hexadiamine linker for methanol oxidation (MOR) and oxygen reduction reaction (ORR). The attachment of Au-PtNPs was further confirmed by XRD, line scanning coupled with Energy-dispersive X-ray spectroscopy (EDS) and cyclic voltammetry (CV). The Au-PtNPs modified electrode exhibits higher heterogeneous electron transfer rate constant of 4.12×10-3 cm s-1 than bare (1.01×10-4 cm s-1) and PtNPs (1.77×10-4 cm s-1) modified GC electrodes. Further, the Au-PtNPs modified electrode exhibited the composition dependent activity towards MOR and ORR. It was found that the Pt:Au of 1:0.09 modified electrode shows 8-fold sensitive oxidation for MOR when compared to commercial Pt/C catalyst. The present Au-PtNPs catalyst exhibit a great enhanced catalytic activity in terms of mass activity (132 mA mg Pt-1) and excellent stability relative to the commercial Pt/C catalyst.

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Publication details

The article was received on 23 Nov 2017, accepted on 08 May 2018 and first published on 10 May 2018


Article type: Paper
DOI: 10.1039/C7SE00565B
Citation: Sustainable Energy Fuels, 2018, Accepted Manuscript
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    Displacement reduction routed Au-Pt bimetallic nanoparticles: A highly durable electrocatalyst for methanol oxidation and oxygen reduction

    N.S.K Gowthaman, S. Bharathi, S. Shankar and S. A. John, Sustainable Energy Fuels, 2018, Accepted Manuscript , DOI: 10.1039/C7SE00565B

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