Electrochemical Fabrication of Well-Defined Spherical Iridium Nanoparticles and Electrocatalytic Activity towards Carbon Monoxide Adlayer Oxidation

Sheasha, Yasser; Soliman, Khaled A.; Sun, Shi‐Gang; Jacob, Timo; Kibler, Ludwig A.

doi:10.1007/s12678-015-0252-3

Cited by 5 publications

(4 citation statements)

References 28 publications

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“…A gradual negative shift in the CO-stripping peak potential is seen as the Pt coverage of the Ir core /Pt shell NPs increases from sub- to full ML (Figure a). Also, the CO-stripping peak of Ir/VC is broader than that of Pt/VC, as reported previously. , …”

Section: Resultssupporting

confidence: 86%

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Nanoengineered Ir_core@Pt_shell Nanoparticles with Controlled Pt Shell Coverages for Direct Methanol Electro-Oxidation

Sawy

Birss

2018

ACS Appl. Mater. Interfaces

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The design and application of bimetallic alloy nanoparticles (NPs) for electrocatalytic applications are challenged by the need to clearly identify and understand the individual effect of each component. In the present work, the focus has been on PtIr NPs, with alloyed NPs being previously shown to be active toward the methanol oxidation reaction (MOR), but for which the mode of action of the Ir component remains uncertain. We have therefore nanoengineered a family of Ir@Pt NPs, using a modified polyol method, to control the Pt shell coverage (up to 2 monolayers) and thus to allow the separation of the bifunctional and electronic effects of Ir on the Pt activity. It is shown that the Ir core size and crystallinity do not change with the deposition of the Pt shell, as confirmed by transmission electron microscopy and X-ray diffraction. CO stripping and hydrogen underpotential deposition/removal were used for the first time to determine the surface composition of the Ir@Pt NPs. It is shown that the Ir enhances the MOR activity of the Pt primarily through the bifunctional effect, with an optimum Pt coverage of 0.4 of a monolayer. At 60 °C, an additional electronic effect of Ir on Pt can be discerned, causing an inhibition in the MOR rate by weakening the adsorption of methanol on the Pt, thus helping to remove the adsorbed CO intermediate from the shell surface.

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Section: Resultssupporting

confidence: 86%

“…Also, the CO-stripping peak of Ir/VC is broader than that of Pt/VC, as reported previously. 24,48 It is known that CO stripping takes place according to reactions 1 and 2. In the case of Pt, 0.3 V (0.8 to 1.1) is required to form a ML of OH ads (reaction 1), 49 whereas in the case of Ir, this process requires 0.65 V (0.45 to 1.1 V).…”

Section: Resultsmentioning

confidence: 99%

Nanoengineered Ir_core@Pt_shell Nanoparticles with Controlled Pt Shell Coverages for Direct Methanol Electro-Oxidation

Sawy

Birss

2018

ACS Appl. Mater. Interfaces

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“…[33,34] By subjecting the glassy carbon electrodes to five potential cycles in the above mentioned solution, between À0.26 V and 1.2 V vs. SCE at a scan rate of 50 mV s À1 , the surface can be cleaned and activated for deposition. [35] 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 Potentiodynamic Deposition Potentiodynamic deposition from trivalent and hexavalent solutions was performed in aerated 10 mM solutions of chromium(III) sulfate and chromium(VI) oxide, respectively. 0.1 M sulfuric acid was used as a supporting electrolyte in both cases.…”

Section: Substrate Preparationmentioning

confidence: 99%

Potentiodynamic Chromium Deposition from Trivalent and Hexavalent Systems on Glassy Carbon Electrodes: Initial Stages and Mechanistic Insights

et al. 2017

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Developing a functional Cr(III) electrolyte to replace carcinogenic and toxic Cr(VI) electroplating requires a deeper understanding of the deposition mechanisms. Hence, this study investigates and compares the growth of chromium on inert glassy carbon (GC) electrodes from low-concentration Cr(III) and Cr(VI) electrolytes, using a novel potentiodynamic deposition scheme. This allows the initial stages of deposition to be probed, which are crucial for determining the overall deposition mechanism. Scanning electron microscopy shows that, for both systems, micrometer-sized hexagonal chromium hydride crystals could be deposited on GC, thus serving to be the first reporting of such structures. In addition, by increasing the deposition time, the changes in a particle structure for both systems were tracked; therefore, possible areas of similarity as well as key differences could be identified, which, when addressed may provide a more viable, environmentally friendly trivalent electrolyte for chromium electroplating.

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“…Hitherto, Kibler et al employed square-wave potential procedure and successfully electrodeposited Ir nanoparticles on a glassy carbon electrode. Although the nanoparticles were free from surfactants, they were nanospheres enclosed with poly-crystal facets [23]. In earlier work, Dai et al reported that Pt nanocubes could be directly deposited onto Cu foil by reacting appropriate aqueous solutions of K 2 PtCl 4 with Cu foil via a galvanic displacement reaction for given reaction times [22].…”

Section: Introductionmentioning

confidence: 99%

A Simple and Fast Method to Synthesize Cubic Iridium Nanoparticles with Clean Surface Free from Surfactants

Zhang

Shi

et al. 2019

Nanomaterials

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Cubic Iridium nanoparticles without any surfactants on the surface have been synthesized successfully in this work. The process of synthesis was quite simple by just injecting one drop of 400 µL solution containing Iridium precursor onto Cu foil (1 cm × 1 cm), and through galvanic reaction between the Ir precursor and Cu foil, the cubic Iridium nanoparticle could be obtained quite quickly (<30 s). The Cu foil played the roles of both reducing agent and substrate. This method could also be employed to synthesize cubic nanoparticles of other Pt-group metals such as Rh. By employing this method, cubic metal nanoparticles with surfactant-free surfaces could be produced economically and efficiently, and as a result, a realistic relationship between structure and catalytic activity could be established.

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Electrochemical Fabrication of Well-Defined Spherical Iridium Nanoparticles and Electrocatalytic Activity towards Carbon Monoxide Adlayer Oxidation

Cited by 5 publications

References 28 publications

Nanoengineered Ir_core@Pt_shell Nanoparticles with Controlled Pt Shell Coverages for Direct Methanol Electro-Oxidation

Nanoengineered Ir_core@Pt_shell Nanoparticles with Controlled Pt Shell Coverages for Direct Methanol Electro-Oxidation

Potentiodynamic Chromium Deposition from Trivalent and Hexavalent Systems on Glassy Carbon Electrodes: Initial Stages and Mechanistic Insights

A Simple and Fast Method to Synthesize Cubic Iridium Nanoparticles with Clean Surface Free from Surfactants

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Electrochemical Fabrication of Well-Defined Spherical Iridium Nanoparticles and Electrocatalytic Activity towards Carbon Monoxide Adlayer Oxidation

Cited by 5 publications

References 28 publications

Nanoengineered Ircore@Ptshell Nanoparticles with Controlled Pt Shell Coverages for Direct Methanol Electro-Oxidation

Nanoengineered Ircore@Ptshell Nanoparticles with Controlled Pt Shell Coverages for Direct Methanol Electro-Oxidation

Potentiodynamic Chromium Deposition from Trivalent and Hexavalent Systems on Glassy Carbon Electrodes: Initial Stages and Mechanistic Insights

A Simple and Fast Method to Synthesize Cubic Iridium Nanoparticles with Clean Surface Free from Surfactants

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Product

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Nanoengineered Ir_core@Pt_shell Nanoparticles with Controlled Pt Shell Coverages for Direct Methanol Electro-Oxidation

Nanoengineered Ir_core@Pt_shell Nanoparticles with Controlled Pt Shell Coverages for Direct Methanol Electro-Oxidation