Hydrogen Electrocatalysis on Single Crystals and on Nanostructured Electrodes

Santos, Elizabeth; Hindelang, Peter; Quaino, Paola; Schulz, Eduardo Nicolás; Soldano, Germán; Schmickler, Wolfgang

doi:10.1002/cphc.201100309

Cited by 76 publications

(91 citation statements)

References 27 publications

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“…The calculations follow exactly our previous works [10,25], to which we refer for the details. In Fig.…”

Section: Discussionmentioning

confidence: 76%

“…Therefore, a DFT calculation for the free energy of adsorption of the weakly adsorbed species in the presence of a monolayer of upd hydrogen gives often quite high (unfavorable) values for the the adsorption energy of the former species. We have discussed this point in detail in a a recent communication [25], where we have also calculated the isotherms for both species of adsorbed hydrogen on Pt(111). In any case, the interaction between the two species makes it quite difficult to calculate the adsorption free energy of the true intermediate state by DFT.…”

Section: Discussionmentioning

confidence: 99%

“…This entails that its orbitals are compact, and the interaction with the hydrogen atom falls off rapidly with distance [25], even though the adsorption energy is quite favorable (see Fig. 3).…”

Section: Discussionmentioning

confidence: 99%

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Volcano plots in hydrogen electrocatalysis – uses and abuses

Quaino¹,

Juárez²,

Santos³

et al. 2014

Beilstein J. Nanotechnol.

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494

415

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SummarySabatier’s principle suggests, that for hydrogen evolution a plot of the rate constant versus the hydrogen adsorption energy should result in a volcano, and several such plots have been presented in the literature. A thorough examination of the data shows, that there is no volcano once the oxide-covered metals are left out. We examine the factors that govern the reaction rate in the light of our own theory and conclude, that Sabatier’s principle is only one of several factors that determine the rate. With the exception of nickel and cobalt, the reaction rate does not decrease for highly exothermic hydrogen adsorption as predicted, because the reaction passes through more suitable intermediate states. The case of nickel is given special attention; since it is a 3d metal, its orbitals are compact and the overlap with hydrogen is too low to make it a good catalyst.

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“…The calculations follow exactly our previous works [10,25], to which we refer for the details. In Fig.…”

Section: Discussionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 99%

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Volcano plots in hydrogen electrocatalysis – uses and abuses

Quaino¹,

Juárez²,

Santos³

et al. 2014

Beilstein J. Nanotechnol.

Self Cite

494

415

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“…It can be speculated that in alkaline solutions, more sluggish reaction kinetics on Rh/Au(111) than on Rh(poly) and Pt(poly) is caused by the slower hydrogen intermediate adsorption than in acid solutions in which Rh/Au(111) is comparably active as Pt. 33 Exceptionally high activity of Rh/Au(111) for HER was attributed to the strong electronic interaction between Au(111) and deposited Rh, which promotes the adsorption of the hydrogen intermediate species as the first step in HER mechanism, 33,36,37 and thus enhances the overall reaction rate. Therefore, hereby presented results have corroborated that the electronic interaction between Au(111) substrate and the deposited Rh islands, which is now evidenced experimentally by the shift of the Rh 3d 5/2 photoelectron lines in the XPS spectra, is responsible for the enhanced activity of Rh/Au(111) for HER.…”

Section: Resultsmentioning

confidence: 99%

“…33 These experimental findings have successfully corroborated former theoretical studies, which have predicted high activity of Rh/Au(111) electrodes for HER as a consequence of the strong electronic interaction between Au(111) substrate and Rh overlayer. 36,37 The aim of this work is to correlate surface properties of Rh/Au(111) obtained by the facile spontaneous deposition method with its high activity for HER in alkaline solution. Surface structure of the obtained bimetallic Rh/Au(111) electrode was observed by ex situ AFM at the nano-scale level.…”

mentioning

confidence: 99%

Spontaneously Deposited Rh on Au(111) Observed by AFM and XPS: Electrocatalysis of Hydrogen Evolution

Štrbac

Smiljanić

Rakočević

2016

J. Electrochem. Soc.

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Rhodium nanoislands were spontaneously deposited on Au(111) up to a full coverage. Obtained Rh/Au(111) bimetallic surface was characterized ex situ by Atomic Force Microscopy imaging and by X-Ray Photoelectron Microscopy, while in situ characterization was performed by Cyclic Voltammetry in 0.1 M NaOH solution. Pronounced catalysis of hydrogen evolution reaction has been observed on Rh modified Au(111) surface compared to bare Au(111). This is ascribed to the suitable geometry of obtained Rh/Au(111) nanostructured electrode surface providing large number of active sites and to the electronic interaction between Au(111) substrate and Rh deposit.Bimetallic electrodes consisting of noble metal substrate modified by a foreign metal deposit are still in the focus of interest in electrocatalysis starting from early publications. 1-4 Tailoring bimetallic electrodes with pronounced electrocatalytic activity compared to the activity of the substrate alone or to the both constituting metals is a demanding task regarding the chemical nature and the structure of the substrate and deposit, which should result in improved surface chemistry and geometry with respect to the active surface sites and/or to the electronic effect. Well-ordered noble metal electrodes modified by submonolayer to a few layers thick deposit of highly active metals from platinum group are the most convenient bimetallic model systems for fundamental studies of the electrocatalytic activity of such various nanostructures for fuel cell reactions. [5][6][7] Structural, electronic and chemical properties of well-defined bimetallic surfaces are examined ex situ by common techniques including Scanning Probe Microscopy (SPM), and X-ray Photoelectron Spectroscopy (XPS). 8,9 With the advent of in situ microscopic and spectroscopic techniques, such as Scanning Tunneling Microscopy (STM), 10 XPS, 11 Surface X-ray Scattering (SXS) and X-ray Absorption Spectroscopy (XAS), 12 it became possible to observe the structure of bimetallic surface and to determine its chemical composition and oxidation state of constituting metals under defined electrochemical conditions or during electrocatalytic reactions.For the preparation of bimetallic electrodes with well-defined structure, various deposition methods were employed including electrochemical deposition on nonreconstructed 13 or reconstructed single crystal surfaces, 14 surface limited redox replacement, 15-18 defectmediated growth, 19 and spontaneous deposition. 20,21 The spontaneous deposition method, which is explored in this work, assumes several processes that occur on the electrode surface during its immersion into the depositing metal ions solution at open circuit potential. These involve either irreversible adsorption of metal ion complexes or electroless deposition in which depositing metal ions are reduced by substrate atoms which are oxidized, or a combination of both. Finally obtained bimetallic surface consists of three-dimensional foreign metal nanoislands with the coverage up to a monolayer. In some cases, w...

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