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A density functional theory approach to mushroom-like platinum clusters on palladium-shell over Au core nanoparticles for high electrocatalytic activity
KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).ORCID-id: 0000-0002-3282-0711
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2011 (Engelska)Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 13, nr 12, s. 5441-5449Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Recently, it was found that Pt clusters deposited on Pd shell over Au core nanoparticles (Au@Pd@Pt NPs) exhibit unusually high electrocatalytic activity for the electro-oxidation of formic acid (P. P. Fang, S. Duan, et al., Chem. Sci., 2011, 2, 531-539). In an attempt to offer an explanation, we used here carbon monoxide (CO) as probed molecules, and applied density functional theory (DFT) to simulate the surface Raman spectra of CO at this core-shell-cluster NPs with a two monolayer thickness of Pd shell and various Pt cluster coverage. Our DFT results show that the calculated Pt coverage dependent spectra fit the experimental ones well only if the Pt clusters adopt a mushroom-like structure, while currently the island-like structure is the widely accepted model, which follows the Volmer-Weber growth mode. This result infers that there should be a new growth mode, i.e., the mushroom growth mode as proposed in the present work, for Au@Pd@Pt NPs. We suggest that such a mushroom-like structure may offer novel active sites, which accounts for the observed high electrocatalytic activity of Au@Pd@Pt NPs.

Ort, förlag, år, upplaga, sidor
Cambridge: ROYAL SOC CHEMISTRY , 2011. Vol. 13, nr 12, s. 5441-5449
Nyckelord [en]
ADSORBATE-ADSORBATE INTERACTIONS; SINGLE-CRYSTAL SURFACES; AUGMENTED-WAVE METHOD; OXYGEN-REDUCTION; CARBON-MONOXIDE; FORMIC-ACID; PD(111) SURFACE; AB-INITIO; BIMETALLIC NANODENDRITES; METAL NANOCRYSTALS
Nationell ämneskategori
Fysikalisk kemi
Identifikatorer
URN: urn:nbn:se:kth:diva-32126DOI: 10.1039/c1cp20096hISI: 000288219700029PubMedID: 21350738Scopus ID: 2-s2.0-79952649242OAI: oai:DiVA.org:kth-32126DiVA, id: diva2:409323
Anmärkning
QC 20110407Tillgänglig från: 2011-04-07 Skapad: 2011-04-07 Senast uppdaterad: 2020-03-09Bibliografiskt granskad
Ingår i avhandling
1. Geometrical and Electronic Structures at Molecule-Metal Interfaces from Theoretical Modeling
Öppna denna publikation i ny flik eller fönster >>Geometrical and Electronic Structures at Molecule-Metal Interfaces from Theoretical Modeling
2012 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

In this thesis, we focus on theoretical investigations on metal interfaces where many heterogeneous chemical reactions take place. Surface-enhanced Raman scattering (SERS) spectroscopy and the modern electrochemical methods are important in-situ techniques that have been widely employed for a variety of applications. Theoretical simulations have become an indispensable tool to infer the molecular details of interfacial structures that are not directly accessible from experimental measurements. In this context, we have proposed several new theoretical models for both SERS and interfacial electrochemistry, which allow us to provide molecular-level understanding of the interfacial structures under the realistic experimental conditions.

 

The first part of the thesis has addressed the basic theory of SERS that offers the vibrational structure of the interfacial molecules. It is well known that the huge enhancement of Raman intensity in this technique can be attributed to two independent factors, namely the physical and chemical enhancements. The former is resulted from the enhanced electromagnetic field induced by the plasmonic excitations, while the latter comes from the changing of interaction between the molecule and the surface. The interplay between these two enhancement factors, which has long been an issue of debate, is revealed in this thesis. They are coupled through molecular polarizability. A practical computational approach is proposed and used to demonstrate the importance of the coupling on different molecular systems. It is found that for certain systems the coupling factor can be as large as 106. This finding is of great importance towards a comprehensive understanding of the SERS mechanisms and a quantitative prediction of the enhancement factor.

 

The other part of the thesis is devoted to the theory of interfacial electrochemistry, in particular the effects of water solution. A novel protocol that combines classical molecular dynamics (MD) and the first principles density functional theory (DFT) calculations is proposed to address the statistical behavior of interfacial properties. Special attention has been paid to the work function of Pt(111) surface and CO adsorption energy on Pt(111) surface in aqueous solution. It has been found that in this case the work function of Pt surface illustrates a surprisingly broad distribution under the room temperature, sheds new light on the understanding of reaction activity of the surface. The proposed protocol is able to provide results in very good agreement with experiments and should be applied routinely in future studies.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2012. s. xii, 67
Serie
Trita-BIO-Report, ISSN 1654-2312 ; 2012:14
Nyckelord
SERS, Electrochemistry, DFT, MD
Nationell ämneskategori
Fysikalisk kemi
Forskningsämne
SRA - Energi
Identifikatorer
urn:nbn:se:kth:diva-94120 (URN)978-91-7501-372-5 (ISBN)
Disputation
2012-06-07, FB54, Albanova University Center, Roslagstullsbacken 21, Stockholm, 10:00 (Engelska)
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QC 20120515

Tillgänglig från: 2012-05-15 Skapad: 2012-05-07 Senast uppdaterad: 2013-04-18Bibliografiskt granskad

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Duan, SaiLuo, Yi

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