Formation of Single-Layered Pt Islands on Au(111) Using Irreversible Adsorption of Pt and Selective Adsorption of CO to Pt

Kim, Jandee; Shin, Dongwan; Rhee, Choong Kyun; Yoon, Seong Ho

doi:10.1021/la500005p

Cited by 12 publications

(12 citation statements)

References 20 publications

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“…The heights of uncovered single-layered islands differ from those of the first layers in multiple-layered islands. The single-layered islands of (√3×√3)R30° arrangement is ~0.08 nm high, which is consistent with the uncovered single-layered Pt islands prepared with 10 -5 M Pt precursor solution 54 . Such uncovered single-layered Pt islands are most likely to be Pt islands alloyed with Au, in which the Pt atoms probably submerge into the top Au layer in a 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 13 (√3×√3)R30° pattern as depicted at the left-hand side of Figure 4(c).…”

Section: Methodssupporting

confidence: 83%

Contrasting Electrochemical Behavior of CO, Hydrogen, and Ethanol on Single-Layered and Multiple-Layered Pt Islands on Au Surfaces

et al. 2014

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This work presents formation of single-layered Pt islands on Au electrodes using CO route and the electrochemical behavior of CO, hydrogen, and ethanol as investigated with scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry. Conventional route, consisting of irreversible adsorption of Pt precursor ions (10 -3 M PtCl 4 2-in 0.05 M H 2 SO 4 ) and subsequent electrochemical reduction, resulted in multiple-layered Pt islands; CO route, utilizing CO adsorption to protect pre-existing Pt islands from irreversible adsorption of Pt, exclusively produced single-layered Pt islands.Furthermore, STM results implied that single-layered Pt islands on Au (111) were islands of alloyed Pt in a (√3×√3)R30° arrangement, while multiple-layered islands were stacked layers of Pt in an (1×1) array. The coverages of deposited Pt estimated from STM and XPS measurements were quantitatively consistent with each other to confirm existence of the single-layered Pt islands. Coulometric analyses of adsorbed CO and hydrogen indicated lower adsorption stoichiometry of hydrogen on Pt islands prepared by the two deposition routes, especially when the deposited amount of Pt was small. Comparison of the coulometric coverages of CO and hydrogen with electrochemically active Pt coverages estimated with STM results supported that the adsorption stoichiometries of CO and hydrogen were higher on single-layered Pt islands than on multiple-layered ones, roughly by factor of ~1.8. Also, ethanol oxidation was enhanced on single-layered Pt islands approximately ~4 times in average referring to Pt(poly), while the enhancement factor on multiple-layered ones was ~1.5. Thus, this work demonstrated that CO route exclusively produced single-layered Pt islands on Au, contrasting with multiple-layered islands in various electrochemical aspects.

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Section: Methodssupporting

confidence: 83%

Contrasting Electrochemical Behavior of CO, Hydrogen, and Ethanol on Single-Layered and Multiple-Layered Pt Islands on Au Surfaces

et al. 2014

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“…This method is considered as a simpler means to platinize the gold substrate than those reported in the literatures. 17,25 In situ STM revealed an ordered (2 × 2)-CO adlayer on the Pt deposit, as compared with a disordered Pt deposit without CO. This Pt-modified Au(111) (denoted as Pt/Au(111)) electrode was examined with regard to its activity toward oxygen reduction reaction (ORR).…”

mentioning

confidence: 96%

Carbon Monoxide Promoted Deposition of Ordered Pt Adlayer on Au(111) and Its Electrocatalytic Properties

Liao

Yau

2015

J. Electrochem. Soc.

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In situ scanning tunneling microscopy (STM) was used to examine the microstructures of platinum (Pt) deposited on ordered Au(111) substrate in aqueous Na 2 PtCl 6 solution saturated with carbon monoxide (CO) with and without potential control at room temperature. PtCl 6 2− complexes were reduced to Pt atoms by CO molecules and deposited on Au(111) in a hexagonal array without potential control. The adsorption of CO molecules first mobilized and rearranged Pt adatoms on Au(111) from disordered Pt aggregates to 0.9 nm wide tortuous stripes, and then to patches of ordered Pt adatoms at 0.1 V (versus reversible hydrogen electrode). Electrodeposition of Pt in the presence of CO ceased with a monatomic Pt film capped with CO molecules arranged in a (2 × 2) array at 0.1 V. The CO monolayer adsorbed on Pt/Au(111) was stripped off at 0.96 V in 0.1 M H 2 SO 4 , as compared with 0.83 V observed with Pt(111). The E 1/2 potential for oxygen reduction reaction (ORR) observed with the Pt-modified Au(111) electrode was 0.81 V in sulfuric acid, which is 0.16 V more positive than that of Pt(111). The microstructures of the as-prepared Pt monolayer on Au(111) changed with potential cycling between 0.05 and 1.0 V. Platinum (Pt) metal is active in catalyzing a number of electrochemical reactions, such as hydrogen evolution and oxidation, 1 oxidation of methanol, 2 and oxygen reduction reaction. 3,4 Since these electrochemical reactions all occur at the interface of the Pt electrode, it is important to learn the electrochemical characteristics of ultrathin Pt film, which can lead to cost-effective uses of Pt. The preparation and characterization of thin Pt films have been studied in the last decade and has been reviewed. 5 Substrates for Pt deposition range from noble transition metal substrates (Au, Ru, and so on), 6,7 to semiconductors (silicon 8 and TiO 2 9 ), carbon materials (graphite, 10,11 carbon nanotubes 12,13 ), and polymers (polyaniline, 14 Nafion 15 ). These Pt-modified electrodes yield new uses in electrocatalysis and electroanalysis.Of close relevance to this study -Pt deposited on gold substrate -has been examined in vacuum and electrochemical environments. 6,16-20 Scanning tunneling microscopy (STM) has been used to study Pt electrodeposition on Au(111) and Au(100) ordered electrodes, which reveals that Pt nucleates preferentially in steps, and develops into 3D clusters and cauliflower type clusters on these substrates, 21 while X-ray diffraction shows epitaxial deposition of Pt on Au(111) electrode with Pt adatoms occupying face-center cubic (fcc) three-fold sites. 18,22 Smooth Pt monolayers have been prepared by galvanic replacement of a predeposited Cu layer 19,20 or by electrodeposition in the presence of carbon monoxide, whose adsorption on Pt deposit hindered further Pt reduction. 23 As for preparing multilayer Pt films, a self-terminating electrodeposition process in K 2 PtCl 4 -NaCl electrolyte has been devised, which allows control over morphology and film thickness. 24 We employed in situ STM and infrared spe...

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“…For the fits of the investigated voltammograms, four peak components of FAO were employed as exemplified in the voltammogram of Pt(1)/Bi/Pt NP (Figure a). Two dehydrogenation processes at different potentials on metallic surfaces were suggested to take place. ,, One dehydrogenation peaking at ∼0.2 V (DH1) proceeds without poison formation on Pt ensembles (i.e., Pt domains surrounded by adsorbed Bi , or Pt deposits on Au − ). Meanwhile, the other dehydrogenation peaking at ∼0.4 V (DH2) occurs concomitantly with dehydration on wide Pt surfaces (e.g., Pt disk).…”

Section: Resultsmentioning

confidence: 99%

Pt Deposits on Bi/Pt NP Catalyst for Formic Acid Oxidation: Catalytic Enhancement and Longer Lifetime

2020

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This work presents an improvement in the activity and catalytic lifetime of Pt deposits on Bi-modified Pt nanoparticles (Bi/Pt NP) toward formic acid oxidation (FAO). Using an irreversible adsorption method, Bi was deposited on Pt NP to form Bi/Pt NP and sequentially Pt was deposited on Bi/Pt NP to form Pt/Bi/Pt NP. Voltammetric studies of Pt NP, Bi/Pt NP, and Pt/Bi/Pt NPs supported that Pt deposits of Pt/Bi/Pt NPs provided quite a unique behavior: simultaneous surface oxidation of deposited Pt and Bi and significant resistance to the oxidative removal of Bi. Furthermore, combined spectroscopic investigations revealed that the concentration of the employed Pt precursor ion solution determined the amount of deposited Pt from ∼0.2 to ∼0.4 in coverage. The best Pt/Bi/Pt NP catalyst with a Pt coverage of ∼0.25 enhanced the dehydrogenation processes below ∼0.4 V by a factor of more than 2 and increased the FAO current at ∼0.8 V roughly by 15 times, referring to those of Bi/Pt NP. The lifetime measurement works revealed that after the 1000th voltammetric cycle to 0.4 V, the FAO currents of Pt/Bi/Pt NPs were 2 and 4 times higher than those of Bi/Pt NP and Pt NP, respectively. The Pt deposits on Bi/Pt NP were concluded to play two roles in FAO: the promotion of FAO processes to increase the activity and the retardation of Bi oxidative removal to maintain the activity much longer.

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Formation of Single-Layered Pt Islands on Au(111) Using Irreversible Adsorption of Pt and Selective Adsorption of CO to Pt

Cited by 12 publications

References 20 publications

Contrasting Electrochemical Behavior of CO, Hydrogen, and Ethanol on Single-Layered and Multiple-Layered Pt Islands on Au Surfaces

Contrasting Electrochemical Behavior of CO, Hydrogen, and Ethanol on Single-Layered and Multiple-Layered Pt Islands on Au Surfaces

Carbon Monoxide Promoted Deposition of Ordered Pt Adlayer on Au(111) and Its Electrocatalytic Properties

Pt Deposits on Bi/Pt NP Catalyst for Formic Acid Oxidation: Catalytic Enhancement and Longer Lifetime

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