Physico–chemical Modelling of Adlayer Phase Formation via Surface–limited Reactions of Copper in Relation to Sequential Electrodeposition of Multilayered Platinum on Crystalline Gold

Mkwizu, Tumaini S.; Cukrowski, Ignacy

doi:10.1016/j.electacta.2014.09.086

Cited by 14 publications

(20 citation statements)

References 35 publications

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“…According to the authors of this work the SLRR reaction investigated here was determined as second-order with respect to Cu UPD on bare Au substrate and somewhere in the range around 1.3 on subsequent cycles whereby the surface was increasingly covered by Pt. The magnitude of the overall SLRR rate constant was found to decrease gradually with increase of the Pt layer thickness, confirming earlier experimental results obtained in this system where faster reaction kinetics on bare Au film substrate were seen in comparison to that on thickening Pt deposits [115] (Fig. 20).…”

Section: Modelling Of a Multi-cycle Slrr Reactionsupporting

confidence: 91%

“…Work has been done since the very beginning of the development of SLRR based protocols in order to understand best the kinetics of a single-cycle replacement reaction [113,114] and lately also the deposition process as sequence of multiple replacement reactions [115]. Activities along these lines focus mostly on modelling of the potential time dependence at open circuit potential when the redox replacement takes place.…”

Section: Modelling and Mechanistic Aspects Of The Slrr Deposition Promentioning

confidence: 99%

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Recent Advances in the Growth of Metals, Alloys, and Multilayers by Surface Limited Redox Replacement (SLRR) Based Approaches

Dimitrov

2016

Electrochimica Acta

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A B S T R A C TIn the realm of ever increasing importance of nanotechnology, the deposition of ultrathin metal/alloy layers with perfect structure and unique functionality becomes an objective of paramount importance. In the last decade many research groups have been working on the development and application of a new method for epitaxial thin film growth that employs a surface limited redox replacement (SLRR) as a building block reaction. The multiple repetition of this reaction enables the controlled deposition of a monolayer of metal or alloy per cycle. Work in the field has been done on the development of SLRR deposition protocols along with understanding and modelling of the SLRR reaction kinetics, on comparative studies of SLRR based routines, and on other deposition approaches. Most recently, the development of SLRR was extended to the application of all-electroless approaches for carrying out the SLRR (ESLRR). In this paper an overview of all SLRR, ESLRR and related approaches is presented. The description of the background and reaction formalism introduces the method with emphasis on its general applicability and limitations. The discussion then continues with the description of experimental approaches for carrying out a deposition process by SLRR. In this section specific consideration is given to the deposition by shuttling of the working electrode, the flow-cell configuration, the one-cell configuration, and the all-electroless approaches for realizing the repetitive application of a single-cycle SLRR reaction. Next, the ability of these approaches to produce epitaxial, flat and uniform deposits will be discussed through results of electrochemical, in-situ scanning tunneling microscopy, X-ray Photoelectron Spectroscopy and other characterization experiments showing advantages and limitations of SLRR growth in a variety of systems classified into three categories. In the first of these categories Cu, Ag, and Au are used as model systems to introduce the deposition by SLRR. In the second category Pd and Ru deposition by SLRR has been discussed. In the third category all studies concerning a variety of scenarios for Pt deposition by SLRR are presented and in the last part of that section deposition of alloys and multilayers is critically discussed. The paper then continues with a section presenting and discussing modelling approaches of studying the kinetics of a single-cycle SLRR reaction and concludes with the presentation of the extension of modelling to a system where multi-cycle SLRR deposition processes have been investigated. The analysis in this part focuses on the kinetic parameters of the replacement reaction like rate constant, order of the reaction, type of adsorption behavior of the sacrificial metal etc. Finally, this section concludes with a discussion of the mechanistic aspects of the SLRR reaction and more specifically on the factors impacting the deposition process and in turn the resulting structure, morphology, uniformity and continuity of the accordingly grown thin films. The paper a...

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Section: Modelling Of a Multi-cycle Slrr Reactionsupporting

confidence: 91%

Section: Modelling and Mechanistic Aspects Of The Slrr Deposition Promentioning

confidence: 99%

Recent Advances in the Growth of Metals, Alloys, and Multilayers by Surface Limited Redox Replacement (SLRR) Based Approaches

Dimitrov

2016

Electrochimica Acta

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“…This phenomenon could assist us to explain the different kinetics of the displacement reactions. 37 We found a new structure of Pt species, [PtCl 4 ] 2¹ , which was the main species in Pt/Au(111), using in situ PTRF-XAFS. This result provides new insight into the mechanism of SLRR and a different understanding of the behavior of the SLRRderived Pt monolayer of its electrocatalytic properties.…”

mentioning

confidence: 91%

Polarization-dependent Total Reflection Fluorescence X-ray Absorption Fine Structure (PTRF-XAFS) Studies on the Structure of a Pt Monolayer on Au(111) Prepared by the Surface-limited Redox Replacement Reaction

et al. 2017

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We studied the initial stage of a Pt monolayer produced by surface-limited redox replacement (SLRR) using polarizationdependent total reflection fluorescence X-ray absorption fine structure (PTRF-XAFS). Different from the widely accepted understanding that metallic monolayer islands are formed, our XAFS showed that the Pt monolayer, initially present on the Au(111) substrate, was mainly in the form of a planar [PtCl 4 ] 2¹ complex with its molecular plane parallel to Au(111). This result provides a new insight into the mechanism of SLRR.Keywords: X-ray absorption fine structure (XAFS) | Surface-limited redox replacement reaction | Pt monolayerPolymer electrolyte fuel cells (PEFCs), which emit no greenhouse gases, have attracted much attention because of the necessity for the modern society to shift from fossil fuels to clean energy. However, several issues concerning electrocatalysts, including their cost and durability, have greatly inhibited the practical use of PEFCs.1 To reduce the cost of the electrocatalyst, we need to increase the surface area of Pt, which is the main component of the fuel cell catalyst currently. Considerable effort has been devoted to investigating the electrodeposition of Pt. 24Owing to the high surface energy and low wettability of Pt, it is difficult to obtain monolayer deposition on a flat surface with conventional electrodeposition methods.2,4 Brankovic et al. developed a method for Pt monolayer deposition by galvanic displacement of a layer of sacrificial underpotential deposition (UPD) metal, which is called surface-limited redox replacement (SLRR).5 Several sacrificial materials, like Cu, 68 Pb,7,9 and H,10 have been studied for the deposition of Pt monolayers. In addition to Pt, the SLRR was extended to the monolayer deposition of other metals, such as Pd, 11 Ru, 12 and Ag. 5,13 Furthermore, bimetallic monolayer depositions were also achieved by the SLRR.14,15 However, there are only limited numbers of studies regarding the mechanism of the deposition process on atomic levels. In situ scanning tunneling microscopy (STM) was used to study the structure of Pt submonolayers.8 Brankovic et al. systematically studied the reaction mechanism of SLRR to replace the UPD Cu with Pt. They proposed a kinetic model, 16 based on the stoichiometry of SLRR, 6 and also proposed the nucleation mechanism of the Pt monolayer clusters, 17 and the UPD procedure on the Pt monolayer modified surface. 9,15 However, some aspects remain unclear. For example, what is the chemical state and structure of the Pt submonolayers and Pt submonolayerAu interaction, which are very important parameters since they are related to the catalytic properties? To examine the Pt initial structure created by the SLRR of the Cu UPD layer, we applied polarization-dependent total reflection fluorescence-X-ray absorption fine structure (PTRF-XAFS) techniques. 1820PTRF-XAFS is a powerful way of characterizing the surface structure and electronic state of less than a monolayer of adsorbate on atomically flat surfaces even und...

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“…They have treated cases of both mass transfer and kinetic control. More recent publications have taken into account the effects of solution composition [11] as well as those of surface heterogeneity and sequential multilayer formation [12].…”

Section: Kinetic Considerationsmentioning

confidence: 99%

Electrocatalysts Prepared by Galvanic Replacement

et al. 2017

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Galvanic replacement is the spontaneous replacement of surface layers of a metal, M, by a more noble metal, M noble , when the former is treated with a solution containing the latter in ionic form, according to the general replacement reaction: nM + mM noble n+ → nM m+ + mM noble. The reaction is driven by the difference in the equilibrium potential of the two metal/metal ion redox couples and, to avoid parasitic cathodic processes such as oxygen reduction and (in some cases) hydrogen evolution too, both oxygen levels and the pH must be optimized. The resulting bimetallic material can in principle have a M noble-rich shell and M-rich core (denoted as M noble (M)) leading to a possible decrease in noble metal loading and the modification of its properties by the underlying metal M. This paper reviews a number of bimetallic or ternary electrocatalytic materials prepared by galvanic replacement for fuel cell, electrolysis and electrosynthesis reactions. These include oxygen reduction, methanol, formic acid and ethanol oxidation, hydrogen evolution and oxidation, oxygen evolution, borohydride oxidation, and halide reduction. Methods for depositing the precursor metal M on the support material (electrodeposition, electroless deposition, photodeposition) as well as the various options for the support are also reviewed. 1. Principle of Galvanic Replacement/Deposition 1.1. Thermodynamic Considerations When a metal, M (e.g., Cu, Fe, Co, Ni, Al, etc.), is immersed in a solution containing ions of a more noble metal, M noble n+ (e.g., Pt, Au, Pd, Ag, Ru, Ir, Rh, Os, etc.-i.e., a metal with a higher standard potential) then, due to the difference in their standard electrochemical potentials, E 0 noble − E 0 > 0, and provided that the ionic form of M is stable under the given experimental conditions (of temperatue, pH, complexing agents etc.), the following reaction is thermodynamically favored and can take place spontaneously: M noble n+ + n/m M → M noble + n/m M m+ (1) This reaction, which bears similarities with transmetalation reactions between metal complexes [1] and is also known as immersion plating [2] in the plating industry and galvanic replacement [3] in materials chemistry, can be considered to originate from the coupling of the following two half-reactions: M noble n+ + ne − ↔ M noble (E 0 noble) (2) M m+ + me − ↔ M (E 0) (3)

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Physico–chemical Modelling of Adlayer Phase Formation via Surface–limited Reactions of Copper in Relation to Sequential Electrodeposition of Multilayered Platinum on Crystalline Gold

Cited by 14 publications

References 35 publications

Recent Advances in the Growth of Metals, Alloys, and Multilayers by Surface Limited Redox Replacement (SLRR) Based Approaches

Recent Advances in the Growth of Metals, Alloys, and Multilayers by Surface Limited Redox Replacement (SLRR) Based Approaches

Polarization-dependent Total Reflection Fluorescence X-ray Absorption Fine Structure (PTRF-XAFS) Studies on the Structure of a Pt Monolayer on Au(111) Prepared by the Surface-limited Redox Replacement Reaction

Electrocatalysts Prepared by Galvanic Replacement

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