Nanoporous Au-Pt alloys with pore- and ligament size down to few nanometers were fabricated by dealloying Ag-Au-Pt. Owing to the small structure size and large specific surface area, the surface stress and its variation give rise to significant stress and strain in the bulk of these materials. In fact, dilatometry experiments find electrochemical actuation with large reversible strain amplitude. The linear strain reaches approximately 1.3% and strain energy density is up to 6.0 MJ/m(3). The associated stresses may approach the elastic limit of the alloy.

The piezoelectric detection has been proved sensitive to surface stress change of platinum foil electrodes in sulfate solutions of various pH values and sodium hydroxide solution. Electrocapillary-like curves were successfully obtained from the measured piezoelectric signals as a function of potential. The potential of electrocapilla .ry maximum decreases linearly with pH at the rate of -40 mV/pH. The potential of electrocapillary minimum found in the anodic potential scan was 0.35V more positive than the equilibrium potential of PtO/Pt system. It appears that the electrocapillary maximum is connected with a reconstruction or place exchange step of the oxygenated platinum surface corresponding to PrO monolayer.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.129.182.74 Downloaded on 2015-06-17 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.129.182.74 Downloaded on 2015-06-17 to IP

No abstract

No abstract

Absolute values of changes in surface energy of gold electrode in perchlorate solutions with and without iodide ions were measured by a laser‐beam deflection method. The potential of the electrocapillary maximum or potential of zero charge (pzc) obtained by the laser‐beam deflection method was in good agreement with that obtained previously by a piezoelectric technique. The derivative of surface energy with electrode potential, −false(∂γs/∂Efalse) , was quite different from the surface charge density, qnormalm , obtained with integration of current density in the cyclic voltammogram, indicating that the simple Lippmann equation, that is, −false(∂γs/∂Efalse)=qnormalm , did not hold. Particularly, −false(∂γs/∂Efalse) took a maximum near the potential at which the charge transfer of adsorbed iodide ions occurred to form the iodine adlayer despite the fact that qnormalm increased monotonically with increasing potential. The above results obtained by the laser‐beam deflection method were also consistent with those obtained previously by the piezoelectric technique. The discrepancy between −false(∂γs/∂Efalse) and qnormalm was ascribed to the changes in surface elastic strain accompanied by the structural changes of the adlayer. © 1999 The Electrochemical Society. All rights reserved.