Homo- and hetero-epitaxial deposition of Au by surface limited redox replacement of Pb underpotentially deposited layer in one-cell configuration

Mitchell, Corey; Fayette, Matthew; Dimitrov, Nikolay

doi:10.1016/j.electacta.2012.08.024

Cited by 31 publications

(56 citation statements)

References 68 publications

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“…This result is far from anticipated given the finite amount of Au (∼0.15 ML) that can be reduced from a rapidly formed complete ML of adsorbed Au complex, per cycle of spontaneous deposition. 30 The additional amount of reduced Au in this case was hypothesized to be associated with the electroless reduction of adsorbed [AuCl 4 ] − complex enabled solely by the Pt substrate. In more detail, the Pt is susceptible to oxidation in a potential range positive to 0.1V (MSE) whereby the Au complex can be reduced through a bulk deposition process.…”

Section: Resultsmentioning

confidence: 99%

“…Ideally, based on the ability of nitric acid treatment to remove virtually all adsorbates and even metal deposits from Au and Pt surfaces 30,[58][59][60] one would expect, that in the absence of side processes accompanying the adsorption step, no Au of any kind should remain on the Pt surface after the treatment. In Figure 2 it can be seen that, although any adsorbate is believed to be removed from the crystals surface, a portion of Au terminated surface has still been developed.…”

Section: Resultsmentioning

confidence: 99%

“…The amount of material deposited during one SD event is limited to the amount of complex strongly adsorbed to the substrate which allows for the deposition amount to be controlled at a minimum of this level. 45 30 In this work, the spontaneous deposition of Au on Pt will be demonstrated and studied systematically as a way to decorate Pt surfaces with sub-monolayer to several layers of Au. It will be shown that in the system of interest the SD takes place as a hybrid process in which the conventional reduction of adsorbed [AuCl 4 ] − complex is accompanied by an electroless reduction of the same complex coupled with Pt surface oxidation over the course of adsorption.…”

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confidence: 99%

“…Because of this, strategies such as surface limited redox replacement (SLRR), 6,[18][19][20][21][22][23][24][25][26][27][28][29][30] or limited ion adsorption on the substrate. [18][19][20][21][22][23][24][25][26]28,29,50,51 These factors ultimately result in the operation of a cyclic process that allows for the deposition of a strict amount of material (usually limited to a ML) per cycle rendering the deposit thickness finely controllable.…”

mentioning

confidence: 99%

“…16,17 Therefore, complete coverage of the substrate can be ensured, only by the deposition of films of significant thicknesses that, in turn, can be controlled solely by charge calculations over the course of deposition. Because of this, strategies such as surface limited redox replacement (SLRR), 6,[18][19][20][21][22][23][24][25][26][27][28][29][30] Defect-Mediated Growth (DMG), 31 Surfactant Mediated Growth (SMG), 32 Self-Terminating Growth (STG), 33,34 Forced Deposition (FD) 12,[35][36][37] and Spontaneous Deposition (SD) 11,[37][38][39][40][41][42][43][44][45][46][47][48][49] have * Electrochemical Society Student Member. * * Electrochemical Society Member.…”

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confidence: 99%

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The Spontaneous Deposition of Au on Pt (111) and Polycrystalline Pt

Ambrozik

Mitchell

Dimitrov

2016

J. Electrochem. Soc.

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Gold is epitaxially grown by spontaneous deposition (SD) on Pt(111) and Pt [poly]. It has been demonstrated that in the system of interest the SD takes place as a hybrid process, consisting of the potential-controlled reduction of an adsorbed [AuCl 4 ] − complex along with an electroless reduction of the same complex coupled with Pt surface oxidation over the course of adsorption. This hybrid deposition process is shown to promote an outstanding layer-by-layer growth mode on Pt(111) that involves the formation of smooth films with virtually no surface roughness increase. This finding is seconded by in-situ STM experiments demonstrating that the SD of Au on Au(111) leads to similar growth results. In addition, an adlattice structure of √ 7 × √ 7 r19.1 • is determined for the [AuCl 4 ] − adsorbate on Au (111) suggesting a theoretical deposited amount of about 15% Au surface coverage per SD cycle. It has been shown that a Pt(111) substrate is completely masked after five cycles of SD followed by layer densification in continuity development. It has also been shown that the Au amount deposited specifically through the electroless route can be controlled by the amount of initial Pt oxidation, the concentration of dissolved O 2 , and the duration of [AuCl 4 The deposition of thin noble metal films is an area of significant interest for the fundamental and applied communities alike. Noble metal monolayer, to multilayer structures on a sacrificial substrate allows for the utilization of the beneficial properties of electropositive metals or alloys such as; corrosion resistance and catalytic activity, while minimizing the metals use, thus promoting cost effectiveness. In addition it has been shown that monolayer to bilayer metal films on foreign substrates exhibit different electronic properties and chemisorption trends when compared to the bulk material. This is explained through the alteration of the d-band center and orbital mixing resulting from epitaxial strain and electron ligand effects.1-4 Overall, these unique properties can ultimately enhance a material's catalytic usefulness. 5,6 In addition to this it has also been shown that if a metal substrate is decorated by a sub-monolayer of a foreign metal in a controllable way, a synergism can result between the substrate and the foreign metal. This synergy results in enhanced properties, that in some cases are accompanied by the stabilization of the underlying substrate. [7][8][9][10][11] Adzic et al. have demonstrated that the electrodepostion of 0.26 to 0.33 layers of Au on an underlying Pt substrate not only results in steady oxygen reduction reaction activity but also, after 30,000 cycles, the accordingly decorated catalyst is proven significantly more durable than the Pt catalyst on its own.10 Hazzazi et al. have also shown that Au deposited via forced deposition on Pt with coverages up to 0.73 layers improve a catalysts activity toward the ethanol oxidation reaction. 12The above listed sample of advantages of ultrathin epitaxial and continuous noble metal f...

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Section: Resultsmentioning

confidence: 99%