Surface relaxation phenomena at electrified interfaces: Revealing adsorbate, potential, and solvent effects by combined x-ray diffraction, STM and DFT studies

Saracino, Martino; Broekmann, Peter; Gentz, Knud; Becker, Marco; Keller, Hubert; Janetzko, Florian; Bredow, Thomas; Wandelt, K.; Dosch, H.

doi:10.1103/physrevb.79.115448

Cited by 40 publications

(71 citation statements)

References 52 publications

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“…It has been reported for chlorine adlayers under UHV conditions [18][19][20][21][22][23][24][25] as well as in chloride-containing electrolytes. 6,7,[26][27][28][29][30][31] However, at the electrochemical interface the c͑2 ϫ 2͒ structure was observed only positive of a critical potential ͑−0.4 V Ag/AgCl at a Cl concentration of 10 −3 M͒ by in situ STM, whereas at more negative potentials the ͑1 ϫ 1͒ substrate lattice was visible, suggesting a potential-induced order-disorder phase transition into a dilute adlayer of highly mobile chloride. 28,30 More recently, the surface-normal interface structure of the c͑2 ϫ 2͒ adlayers of Cl and Br on Cu͑001͒ was studied by in situ SXRD, focusing on the halide-copper interlayer spacing.…”

Section: Introductionmentioning

confidence: 64%

“…Specifically, up to now only a few studies have presented detailed measurements of the bond lengths at electrochemical interfaces that could be directly compared to structural data on corresponding anionic adlayer structures under UHV conditions. [4][5][6][7][8][9] Such comparative studies allow to clarify how the presence of the outer part of the double layer alters the chemical bonding of the chemisorbed inner adsorbate layer to the surface and the near surface structure of the metal electrode, which in turn may throw light on the interplay among the interactions of the various species at the interface, the charge distribution, and the interface structure. Here we present a combined surface x-ray diffraction ͑SXRD͒ and density-functional theory ͑DFT͒ study of Cu͑001͒ in hydrochloric acid which reveals that the presence of water and cations in the outer double layer not only introduces relaxations in the spacing of the chemisorbed chloride and the first metal layers but also a reversal of a subsurface lattice modulation as compared to that observed in UHV.…”

Section: Introductionmentioning

confidence: 99%

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Reversal of chloride-induced Cu(001) subsurface buckling in the electrochemical environment: Anin situsurface x-ray diffraction and density functional theory study

et al. 2010

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The interface of Cu͑001͒ electrode surfaces in 10 mM HCl solution was studied by in situ surface x-ray diffraction and density functional theory, focusing on the precise structure of the c͑2 ϫ 2͒ Cl adlayer formed at positive potentials. Crystal truncation rod measurements in this adsorbate phase at a potential of −0.20 V Ag/AgCl reveal distinct differences to corresponding data by Tolentino et al. ͓Surf. Sci. 601, 2962 ͑2007͔͒ for the c͑2 ϫ 2͒ Cl structure formed at the Cu͑001͒-vacuum interface. Although in both environments, the atoms in the second Cu layer exhibit a small vertical corrugation, the sign of this corrugation is reversed. Furthermore, also the Cu-Cl bond distance and the average Cu interlayer spacings at the surface differ. Ab initio calculations performed for this adsorbate system reproduce these effects-specifically the reversal of the subsurface second-layer buckling caused in the presence of coadsorbed water molecules and cations in the outer part of the electrochemical double layer. In addition, studies at more negative potentials reveal a continuous surface phase transition to a disordered Cl adlayer at −0.62 V Ag/AgCl , but indicate a substantial Cl coverage even at the onset of hydrogen evolution.

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Section: Introductionmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Reversal of chloride-induced Cu(001) subsurface buckling in the electrochemical environment: Anin situsurface x-ray diffraction and density functional theory study

et al. 2010

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“…Although chloride and bromide form the same lateral structure on Cu(100) their charge state on Cu(100) is different. Recent in-situ x-ray scattering experiments point to a bromide species which is more discharged in the adsorbed state [31]. The nature of the specifically adsorbed anion has apparently no significant impact on the instantaneous reduction of adsorbed DPV on the halide-modified copper surface, at least for chloride and bromide.…”

Section: Ex-situ Xps Resultsmentioning

confidence: 99%

Organic layers at metal/electrolyte interfaces: molecular structure and reactivity of viologen monolayers

et al. 2008

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“…We used a p(11)-Br model assumed p4 mm space group (a 1 = b 1 = c 1 = 408.6 pm, a = b = g = 908) for the structural analysis as reported previously. [15][16][17] We first optimized the structures along the direction normal to the electrode surface using the specular CTR with 39 reflections. Then we optimized the in-plane structure of Cs and the buckling structure of internal Ag layer using the non-specular CTR and FOR.…”

Section: Methodsmentioning

confidence: 99%

“…Similar fluctuations of FOR was reported for the Cl on Cu(100) and the Br on Cu(100). [16][17][18] We analyzed the CTR and the FOR in CsBr at À0.4 V vs Ag/ AgCl on the basis of the results in LiBr. The fractional order (1/2 1/2) rod in CsBr differs from that in LiBr, as shown in Figures 4 a,b.…”

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Outer Helmholtz Plane of the Electrical Double Layer Formed at the Solid Electrode–Liquid Interface

et al. 2011

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In electrolyte solutions containing alkali-metal cations, the hydrated cations approach to the electrode surface through noncovalent and electrostatic interactions. The cations next to the electrode form a plane parallel to the electrode surface as shown in Figure 1. The plane is called the outer Helmholtz plane (OHP). The microscopic area above the electrode surface including the OHP is named the electrical double layer. In an electrochemical reaction, a reactant must cross the electrical double layer to reach the electrode surface; the structure and physical properties of the electrical double layer are important for fundamental electrochemistry and electrochemical applications such as capacitors and fuel cells. A huge electric field is induced between an electrode surface and the OHP by the localization of ionic species at the OHP, becoming the driving force for a reaction at the electrode. Several models for the electrical double layer were proposed by the pioneers of electrochemistry. [1][2][3][4][5] The Graham and Bockris-Devanathan-Muller (BDM) models are currently accepted for the case where ions are adsorbed specifically on an electrode.[5] Specifically adsorbed ions also form a plane which is called the inner Helmholtz plane (IHP). The BDM model consists of three parts: IHP, OHP, and the diffuse layer. For the molecular orientation of adsorbed water, the modified double layer model is proposed based on vibrational spectroscopy. [6] The specifically adsorbed species at the IHP has been widely studied using scanning probe microscopy and vibrational spectroscopy. In contrast, the microscopic structure of ions in the OHP has not been reported due to the limitation of in situ analytical methods. Recently, Marković et al. reported that the activities for the oxygen reduction and the methanol oxidation reactions depend on the alkali metal cations in the OHP.[7] Activities of the oxygen reduction and the methanol oxidation reactions give the following order on platinum electrodes:They suggested that hydrated Li + and Na + , which interact with adsorbed OH strongly, block the surface active sites for these reactions. Interaction of alkali metal cations with the electrode surface also affects adlayer formation and the structural transition of specifically adsorbed species.[8] Figure 2 shows cyclic voltammograms (CVs) of Ag (100) in CsBr and LiBr. The pair peaks around À0.8 V and the broad peaks at À1.1 V vs Ag/AgCl have been assigned to the order-disorder transition of the adsorbed Br (Br ad ) and the reorientation of surface water, respectively.[9-11] The peak potentials depend on the alkali metal cations significantly. The cations in the OHP, which are not adsorbed on the electrode, definitely affect the electrochemical processes.The nature of the water in the electrical double layer differs from that in the bulk solution. The molecular orientation of adsorbed water depends on the electrode potentials and electrode materials.[12] However, the detailed structural and physical properties of the water above the fi...

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Surface relaxation phenomena at electrified interfaces: Revealing adsorbate, potential, and solvent effects by combined x-ray diffraction, STM and DFT studies

Cited by 40 publications

References 52 publications

Reversal of chloride-induced Cu(001) subsurface buckling in the electrochemical environment: Anin situsurface x-ray diffraction and density functional theory study

Reversal of chloride-induced Cu(001) subsurface buckling in the electrochemical environment: Anin situsurface x-ray diffraction and density functional theory study

Organic layers at metal/electrolyte interfaces: molecular structure and reactivity of viologen monolayers

Outer Helmholtz Plane of the Electrical Double Layer Formed at the Solid Electrode–Liquid Interface

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