Synthesis and Characterization of Au@Pt Nanoparticles with Ultrathin Platinum Overlayers

Banerjee, Ipshita and Kumaran, V and Santhanam, Venugopal (2015) Synthesis and Characterization of Au@Pt Nanoparticles with Ultrathin Platinum Overlayers. In: JOURNAL OF PHYSICAL CHEMISTRY C, 119 (11). pp. 5982-5987.

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Abstract

Gold-core platinum-shell (Au@Pt) nanoparticles with ultrathin platinum overlayers, ranging from submonolayer to two monolayers of platinum atoms, were prepared at room-temperature using a scalable, wet-chemical synthesis route. The synthesis involved the reduction of chloroauric acid with tannic acid to form 5 nm (nominal dia.) gold nanoparticles followed by addition of desired amount of chloroplatinic acid and hydrazine to form platinum overlayers with bulk Pt/Au atomic ratios (Pt surface coverages) corresponding to 0.19 (half monolayer), 0.39 (monolayer), 0.58 (1.5 monolayer) and 0.88 (2 monolayers). The colloidal particles were coated with octadecanethiol and phase-transferred into chlroform-hexane mixture to facilitate sample preparation for structural characterization. The structure of the resultant nanoparticles were determined to be Au@Pt using HRTEM, SAED, XPS, UV-vis and confirmed by cyclic voltammetry (CV) studies. Monolayers of octadecanethiol coated Au@Pt nanoparticles were self-assembled at an air-water interface and transfer printed twice onto a gold substrate to form bilayer films for electrochemical characterization. Electrochemical activity on such films was observed only after the removal of the octadecanethiol ligand coating the nanoparticles, using a RF plasma etching process. The electrochemical activity (HOR, MOR studies) of Au@Pt nanoparticles was found to be highest for particles having a two atom thick platinum overlayer. These nanoparticles can significantly enhance platinum utilization in electrocatalytic applications as their platinum content based activity was three times higher than pure platinum nanoparticles.

Item Type:	Journal Article
Publication:	JOURNAL OF PHYSICAL CHEMISTRY C
Publisher:	AMER CHEMICAL SOC
Additional Information:	Copy right for this article belongs to the AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA
Keywords:	ENHANCED ELECTROCATALYTIC ACTIVITY; CORE-SHELL NANOPARTICLES; FUEL-CELL REACTIONS; METHANOL ELECTROOXIDATION; GOLD NANOPARTICLES; O-2 REDUCTION; BIMETALLIC NANOPARTICLES; SURFACE; MONOLAYER; OXIDATION
Department/Centre:	Division of Mechanical Sciences > Chemical Engineering
Date Deposited:	29 Apr 2015 04:43
Last Modified:	29 Apr 2015 04:43
URI:	http://eprints.iisc.ac.in/id/eprint/51437

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