In Situ Stress Measurement During Hydrogen Sorption on Ultrathin (111)-Textured Pd Films in Alkaline Electrolyte

Shin, Jae Wook; Bertocci, Ugo; Stafford, Gery R.

doi:10.1149/1.3583609

Cited by 21 publications

(18 citation statements)

References 57 publications

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“…4 e), we therefore conclude that ς ad of H on Au is positive valued with a lower bound of +0.3V. The finding for Au is consistent with positive values of ς during H underpotential deposition (UPD) on Pd [7,33] and Pt [7,13]. The positive ς ad imply that tensile strain makes the metal surfaces more binding for hydrogen.…”

Section: B Potential-strain Responsesupporting

confidence: 76%

Mechanical modulation of reaction rates in electrocatalysis

Deng¹,

Smetanin²,

Weißmüller³

2014

Journal of Catalysis

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The paper explores how changes in the lattice parameter at an electrode surface by elastic strain affect the catalytic activity. The focus is on the hydrogen evolution reaction on 111-textured, polycrystalline Au and Pt thin film electrodes in H2SO4 as a model process. A lock-in technique allows the modulation of the reaction current to be measured in situ during small cyclic strain imposed on the electrode. While tensile strain enhances the exchange current density and the reactivity at low overpotential, ∆E, the trend is inverted and the reactivity diminished at higher ∆E. Strain is introduced into the kinetic rate equation for Heyrowsky kinetics by allowing for straindependence of the hydrogen adsorption enthalpy as well as the activation enthalpy. The results link the current modulation to electrocapillary coupling coefficients that are open to investigation by experiment or computer simulation. The inversion in sign of the coupling as the function of ∆E emerges in agreement with experiment.

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Section: B Potential-strain Responsesupporting

confidence: 76%

Mechanical modulation of reaction rates in electrocatalysis

Deng¹,

Smetanin²,

Weißmüller³

2014

Journal of Catalysis

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“…78 Even as the Co approaches monolayer coverage, the misfit strain can be relaxed by adsorbed hydrogen since the Co is known to be hydrogen terminated at these potentials. 12 Hydrogen adsorbed on both Pt 79 and Pd 80,81 show large compressive changes in surface stress. We can therefore conclude that the misfit term in Eqn.…”

Section: Discussionmentioning

confidence: 99%

In Situ Stress Measurements during Cobalt Electrodeposition on (111)-Textured Au

Fayette

Bertocci

Stafford

2016

J. Electrochem. Soc.

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Cantilever curvature was used to examine stress generation during the electrodeposition of Co onto (111)-textured Au from 0.1 mol/L NaClO 4 + 0.001 mol/L Co(ClO 4 ) 2 (pH = 4.8) in films measuring less than 25 nm in thickness and at Co current efficiencies ranging from 65% to 90%. XRD analysis indicates that the Co is face-centered cubic and maintains the (111) texture of the Au substrate, suggesting epitaxial but not pseudomorphic growth on the Au. The stress-thickness product showed a −0.2 N/m compression in the first monolayer followed by increasing tensile stress as the film thickened. The initial compressive stress is most likely due to surface and interface stresses that dominate at submonolayer coverage. Steady state tensile stress, ranging from 0 to +450 MPa, developed in continuous Co films and showed a strong dependence on electrode potential. However, over this potential range there is no change in grain size or growth rate, factors typically associated with tensile stress. We attribute the tensile stress and its potential dependence to the formation of hydrogen stabilized vacancies, defects found to be quite stable in fcc Fe-group metals and alloys deposited under conditions of H + discharge. The use of electrodeposited Co-based materials has attracted much attention over the past several decades owing in part to their interesting magnetic 1-3 and catalytic properties. [4][5][6][7][8][9][10][11] These properties are largely dependent upon the structure and morphology of the electrodeposit, which in the case of cobalt can vary dramatically with overpotential, electrolyte pH, and the presence of strongly adsorbing anions. 2,[12][13][14][15][16]

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“…In situ stress measurements via cantilever-deflection -The stress evolution in the Ptenriched layer, which forms during the de-alloying of PtCu, is measured in situ by continuously tracking the curvature of the borosilicate-glass substrate with reference to its initial value [20][21][22][23][24][25][26][27][28][29][30][31][32]. A schematic of the experimental setup is shown in Figure 1(a), which shows the electrochemical cell and the setup for the cantilever-deflection measurement.…”

Section: Experimental Methodsmentioning

confidence: 99%

Role of Elastic Strain on Electrocatalysis of Oxygen Reduction Reaction on Pt

et al. 2015

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The effect of elastic strain on catalytic activity of platinum (Pt) towards oxygen reduction reaction (ORR) is investigated through de-alloyed Pt-Cu thin films; stress evolution in the dealloyed layer and the mass of the Cu removed are measured in real-time during electrochemical de-alloying of (111)-textured thin-film PtCu (1:1, atom %) electrodes. In situ stress measurements are made using the cantilever-deflection method and nano-gravimetric measurements are made using an electrochemical quartz crystal nanobalance. Upon de-alloying via successive voltammetric sweeps between -0.05 and 1.15 V vs. standard hydrogen electrode, compressive stress develops in the de-alloyed Pt layer at the surface of thin-film PtCu electrodes. The de-alloyed films also exhibit enhanced catalytic activity towards ORR compared to polycrystalline Pt. In situ nanogravimetric measurements reveal that the mass of de-alloyed Cu is approximately 210 ± 46 ng/cm 2 , which corresponds to a de-alloyed layer thickness of 1.2 ± 0.3 monolayers or 0.16 ± 0.04 nm. The average biaxial stress in the de-alloyed layer is estimated to be 4.95 ± 1.3 GPa, which corresponds to an elastic strain of 1.47 ± 0.4%. In addition, density functional theory calculations have been carried out on biaxially strained Pt (111) surface to characterize the effect of strain on its ORR activity; the predicted shift in the limiting potentials due to elastic strain is found to be in good agreement with the experimental shift in the cyclic voltammograms for the dealloyed PtCu thin film electrodes. IntroductionEnhanced catalytic activity of de-alloyed PtCu electrodes towards oxygen reduction (ORR) reaction has been demonstrated in a number of recent investigations in thin-film and coreshell geometries [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The enhancement in catalytic activity is typically attributed to the electronic interaction between the core and shell constituents as well as to the epitaxial mismatch strain in the metallic shell. For example, Strasser et al. [4] demonstrated enhanced catalytic activity of de-alloyed PtCu core-shell nanoparticles towards ORR, which was attributed to the pseudomorphic compressive strain in the Pt-enriched shell. The magnitude of the strain in the Pt-enriched shell was estimated using lattice-constant measurements (via X-ray diffraction). In this work, real-time stress and nano-gravimetric measurements during electrochemical dealloying of thin-film PtCu (1:1, atom %) electrodes are reported. In situ stress measurements are made using the cantilever-deflection method, and nano-gravimetric measurements are made using an electrochemical quartz crystal nanobalance (EQCN). Upon de-alloying via successive voltammetric sweeps between -0.05 and 1.15 V vs. standard hydrogen electrode (SHE), compressive stress develops in the de-alloyed layer region near the surface of thin-film PtCu electrodes. In situ nanogravimetric measurements reveal that the mass of de-alloyed Cu is approximately 210 ± 46 ng/cm 2 , which co...

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In Situ Stress Measurement During Hydrogen Sorption on Ultrathin (111)-Textured Pd Films in Alkaline Electrolyte

Cited by 21 publications

References 57 publications

Mechanical modulation of reaction rates in electrocatalysis

Mechanical modulation of reaction rates in electrocatalysis

In Situ Stress Measurements during Cobalt Electrodeposition on (111)-Textured Au

Role of Elastic Strain on Electrocatalysis of Oxygen Reduction Reaction on Pt

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