Surface Stress Curves for Gold

Lin, Kae‐Long; Beck, T. R.

doi:10.1149/1.2133024

Cited by 58 publications

(37 citation statements)

References 10 publications

(17 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For gold in 1 mM KCl, KNO 3 , or KSO 4 this was around +0.9 V SHE ; for platinum in 1 mM KCl this was at +0.7 V SHE . Values for the point of zero charge reported in the literature are roughly 0 ( 0.4 V SHE for gold 21,27,28 and platinum. 26,29,30 One reason for our relatively high point of zero charge might be the high pH.…”

Section: Resultsmentioning

confidence: 68%

Measuring Electrostatic Double-Layer Forces at High Surface Potentials with the Atomic Force Microscope

1996

View full text Add to dashboard Cite

The aim of this study was to measure interaction forces between surfaces with high electric potentials in aqueous electrolyte solutions. Therefore, the force between a platinum or gold sample, which served as the working electrode, and a silicon nitride tip of an atomic force microscope was measured. Various potentials were applied between the sample and a reference electrode. Experimental results were compared to forces calculated with the Poisson-Boltzmann equation. As predicted by theory, the electrostatic double-layer force changed only in a narrow potential range of about 300 mV and saturated below and above this range. Within this range the repulsion grew with more negative sample potentials. This was expected, since the tip was negatively charged at the high pH chosen. At strong negative sample potentials this saturation was not complete and the force continued to rise slightly when lowering the potential. Another surprising and yet unexplained observation was a weak long-range attraction at positive sample potentials. This attraction decayed with a decay length of typically 50 nm. In parallel, the structure of Au(111) was imaged. We confirmed a ( 3 × p, p > 10) reconstruction at potentials below about -0.3 V SHE and the normal (1 × 1) hexagonal packing above this potential. Above about +0.8 V SHE the (1 × 1) structure disappeared and no crystalline packing was observed anymore.

show abstract

Section: Resultsmentioning

confidence: 68%

Measuring Electrostatic Double-Layer Forces at High Surface Potentials with the Atomic Force Microscope

1996

View full text Add to dashboard Cite

show abstract

“…The experimental procedure for the surface-stress curves was similar to that described previously (3). The platinum ribbon electrode under study was connected as a working electrode to a potentiostat driven by a triangular-wave signal generator at desired fro-* Electrochem!cal Society Active Member.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, electrocapillary-type curves have been measured for solid metals (1)(2)(3)(4)(5)(6)(7). Changes in surface stress for gold measured with an extensometer instrument (1)(2)(3) were shown to be similar to data for mercury and to be in agreement with the Lippmann equation (3). Gold has a wide region of potential in which the surface is free of oxide as for the mercury surface.…”

mentioning

confidence: 99%

Surface Stress Curves for Platinum

Beck

Lin

1979

J. Electrochem. Soc.

Self Cite

View full text Add to dashboard Cite

Electrocapillary-type curves were measured for platinum ribbon electrodes in aqueous salt solutions using an extensometer instrument previously developed, A surface stress maximum was observed which varied with pH with a slope of about --50 mV/pH. This surface stress maximum is attributed to formation of a surface platinum hydride. Immediately positive of this maximum is a region about 0.15-0.4V wide in which platinum exhibits classical electrocapillary behavior. At potentials more positive than this region, the surface stress decreases rapidly due to formation of surface oxides. A surface stress maximum is found for the oxide surface at ~-l.8V.Surface tension measurements using the Lippmann capillary electrometer are well established for the mercury-electrolyte interface. Recently, electrocapillary-type curves have been measured for solid metals (1-7). Changes in surface stress for gold measured with an extensometer instrument (1-3) were shown to be similar to data for mercury and to be in agreement with the Lippmann equation (3). Gold has a wide region of potential in which the surface is free of oxide as for the mercury surface. The present paper presents surface-stress data for platinum measured with the extensometer. Platinum is a metal with surface characteristics dominated by hydride and oxide. ExperimentalPlatinum ribbons, 1.27 • 10 -3 cm thick • 0.318 cm wide X 50 cm long and of 99.9% purity (A. S. Mackay, Incorporated) were used as both working-and counterelectrodes in the extensometer instrument. The surface of the platinum was observed to be smooth on a scanning electron microscope photograph at magnification 5460. The roughness factor was therefore assumed to be unity. A corresponding EDAX (energydispersive analysis of x-rays) measurement showed that the surface was also highly pure. The only significant peaks were: liquid nitrogen microphonics (about 0.4 keV) which is electronic noise in the system due to vibrations of liquid nitrogen boiling in a cold trap, an A1 Ks line (1.49 keV) due to the aluminum support for the Pt sample, the Pt M line (2.1 keV), the Pt L~ line (8.44 keV), and the Pt Lfl line (11.07 keV).Electrolyte solutions prepared from ACS-specification, reagent-grade chemicals and reverse-osmosis water were used. A continuous circulating-electrolyte purification system (3) including a platinum-electrode preelectrolysis cell, a carbon bed, and a nitrogen bubble column were used in the critical experiments to test a fit of the Lippmann equation.The carbon bed was used to adsorb organic impurities from the solution. It was found, however, that at pH above 7 the carbon bed adsorbed the OH-ion and released some surface-active component. The evidence was that addition of KOH to the solution gave a smaller pH change than calculated, and foaming of the electrolyte occurred. Therefore, runs at pH greater than 7 were rejected.

show abstract

“…[23][24][25][26][27][28][29][30] Its chemical stability allows use of a wide range of potentials and electrolytes, and its surface can be chemically modified with alkanethiol monolayers to produce diverse functionality and tune capacitance. [31][32][33][34] Nanoporous gold can be formed by oxidatively stripping silver from a silver-gold alloy either in concentrated (15 M) nitric acid [biener nl6] or by electrochemical etching in 1 M nitric acid.…”

Section: Introductionmentioning

confidence: 99%

Optimized nanoporous materials.

Langham¹,

Jacobs²,

Ong³

et al. 2009

View full text Add to dashboard Cite

Nanoporous materials have maximum practical surface areas for electrical charge storage; every point in an electrode is within a few atoms of an interface at which charge can be stored. Metal-electrolyte interfaces make best use of surface area in porous materials. However, ion transport through long, narrow pores is slow. We seek to understand and optimize the tradeoff between capacity and transport. Modeling and measurements of nanoporous gold electrodes has allowed us to determine design principles, including the fact that these materials can deplete salt from the electrolyte, increasing resistance. We have developed fabrication techniques to demonstrate architectures inspired by these principles that may overcome identified obstacles. A key concept is that electrodes should be as close together as possible; this is likely to involve an interpenetrating pore structure. However, this may prove extremely challenging to fabricate at the finest scales; a hierarchically porous structure can be a worthy compromise.

show abstract

Surface Stress Curves for Gold

Cited by 58 publications

References 10 publications

Measuring Electrostatic Double-Layer Forces at High Surface Potentials with the Atomic Force Microscope

Measuring Electrostatic Double-Layer Forces at High Surface Potentials with the Atomic Force Microscope

Surface Stress Curves for Platinum

Optimized nanoporous materials.

Contact Info

Product

Resources

About