Modulation of electrochemical hydrogen evolution rate by araliphatic thiol monolayers on gold

Muglali, Mutlu Iskender; Erbe, Andreas; Chen, Ying; Barth, Christoph; Koelsch, Patrick; Rohwerder, Michael

doi:10.1016/j.electacta.2012.11.116

Cited by 32 publications

(29 citation statements)

References 77 publications

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“…If changes occur in orientational order via changes in superstructure of the SAM, these should be visible as a peak in the CV [20], but in fact no such changes are observable. Furthermore, potential dependent spectroscopic ellipsometry shows no evidence for any change in the SAM in its adsorbed state [21]. Therefore, changes in number density, orientation and conformation can be ruled out as the source for the observed increase in SFG intensity with decreasing potential up to −1 V.…”

Section: Resultsmentioning

confidence: 99%

Third-order effects in resonant sum-frequency-generation signals at electrified metal/liquid interfaces

et al. 2012

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Vibrational sum-frequency-generation (SFG) spectroscopy experiments at electrified interfaces involve incident laser radiation at frequencies in the IR and near-IR/visible regions as well as a static electric field on the surface. Here we show that mixing the three fields present on the surface can result in third-order effects in resonant SFG signals. This was achieved for closed packed self-assembled monolayers (SAMs) with molecular groups of high optical nonlinearity and surface potentials similar to those typically applied in cyclic voltammograms. Broadband SFG spectroscopy was applied to study a hydrophobic well-ordered araliphatic SAM on a Au(111) surface using a thin-layer analysis cell for spectro-electrochemical investigations in a 100 mM NaOH electrolyte solution. Resonant contributions were experimentally separated from non-resonant contributions of the Au substrate and theoretically analyzed using a fitting function including third-order terms. The resulting ratio of third-order to second-order susceptibilities was estimated to be scriptO(10−10) m/V.

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Section: Resultsmentioning

confidence: 99%

Third-order effects in resonant sum-frequency-generation signals at electrified metal/liquid interfaces

et al. 2012

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“…Self‐assembled monolayers of thiols groups (SAMs) were also employed for the deliberate chemical functionalization of flat bulk gold, platinum and copper electrocatalysts . Thus, gold electrodes involved in the electrochemical reduction of CO 2 in aqueous 0.1 M HCO 3 are modified with 2‐mercaptopropionic acid (MPA), 4‐pyridylethylmercaptan (4‐PEM) and cysteamine (CYS) .…”

Section: Surface Functionalization Of Single‐metal Catalystsmentioning

confidence: 99%

Surface Modification for Promoting Durable, Efficient, and Selective Electrocatalysts

2020

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Intensive research into the design of catalysts involved in energy conversion and fuel cell technologies has allowed great progress in the field. However, durable, efficient and selective electrocatalytic systems for the activation of fuel molecules at the lowest cost are still needed. The most developed strategies consist of tailoring the shape, size and composition of metallic nanomaterials. Yet, deliberate surface modification of the catalysts should be considered as a promising alternative approach. The functionalization of metallic catalysts with organic ligands has been recently demonstrated to promote high catalytic activity. This Review focuses on the functionalization of metallic or alloy catalysts with organic ligands, showing the impact of the surface modification for different materials and different reactions. Hybrid systems based on this alternative strategy could contribute to the elaboration of cutting‐edge systems for electrocatalysis.

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“…[50][51][52][53] In the past, electrochemically interfaced ellipsometry has been used to show the presence of a layer resembling hydrogen after cathodic polarisation of gold electrodes covered with organic molecules. 54,55 Here, we present a study using electrochemical ATR-IR spectroscopy, complemented by simulations, to obtain vibrational spectra of water under different electrode potentials and draw conclusions about the state of the interfacial water at the solid/liquid interface.…”

Section: Introductionmentioning

confidence: 99%

Electrode potential dependent desolvation and resolvation of germanium(100) in contact with aqueous perchlorate electrolytes

Niu

Schulz

Medina

et al. 2017

Phys. Chem. Chem. Phys.

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The electrode potential dependence of the hydration layer on an n-Ge(100) surface was studied by a combination of in situ and operando electrochemical attenuated total reflection infrared (ATR-IR) spectroscopy and real space density functional theory (DFT) calculations. Constant-potential DFT calculations were coupled to a modified generalised Poisson-Boltzmann ion distribution model and applied within an ab initio molecular dynamics (AIMD) scheme. As a result, potential-dependent vibrational spectra of surface species and surface water were obtained, both experimentally and by simulations. The experimental spectra show increasing absorbance from the Ge-H stretching modes at negative potentials, which is associated with an increased negative difference absorbance of water-related OH modes. When the termination transition of germanium from OH to H termination occurs, the surface switches from hydrophilic to hydrophobic. This transition is fully reversible. During the switching, the interface water molecules are displaced from the surface forming a "hydrophobic gap". The gap thickness was experimentally estimated by a continuum electrodynamic model to be ≈2 Å. The calculations showed a shift in the centre of mass of the interface water by ≈0.9 Å due to the surface transformation. The resulting IR spectra of the interfacial water in contact with the hydrophobic Ge-H show an increased absorbance of free OH groups, and a decreased absorbance of strongly hydrogen bound water. Consequently, the surface transformation to a Ge-H terminated surface leads to a surface which is weakening the H-bond network of the interfacial water in contact.

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Modulation of electrochemical hydrogen evolution rate by araliphatic thiol monolayers on gold

Cited by 32 publications

References 77 publications

Third-order effects in resonant sum-frequency-generation signals at electrified metal/liquid interfaces

Third-order effects in resonant sum-frequency-generation signals at electrified metal/liquid interfaces

Surface Modification for Promoting Durable, Efficient, and Selective Electrocatalysts

Electrode potential dependent desolvation and resolvation of germanium(100) in contact with aqueous perchlorate electrolytes

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