Dynamic Stress Analysis Applied to (111)-Textured Pt in HClO_(4) Electrolyte
Manon C. Lafouresse, Ugo Bertocci, Gery R. Stafford
Dynamic stress analysis (DSA) was performed on Pt cantilever electrodes immersed in a 0.1 mol/L HClO_(4) electrolyte. DSA combines elements of electrochemical impedance spectroscopy (EIS) and cantilever curvature. In this paper DSA is used to determine the relationship between surface stress f and charge density q for (111)-textured Pt as a function of steady state potential. The parameter of merit is the stress-charge coefficient, (\xi), a complex number with real ((\xi)r) and imaginary ((\xi)i) parts, which is obtained from the electrochemical impedance Ze and the stress admittance Ys. Three regions of stress-charge behavior have been identified at potentials bound by hydrogen adsorption and platinum oxide formation. In the hydrogen adsorption region, stress and charge are in phase resulting in a positive value of (\xi)r (positive charge induces tensile stress). In the double layer region, r becomes negative (positive charge induces compressive stress); however the actual potential at which this transition occurs may vary by as much as 0.3 V, depending on electrode history. At more positive potential (\xi)r remains negative in the early oxide region, where the reversible adsorption of O occurs. Only at more positive potential, where place exchange between Pt and O occurs and the surface layer of PtO becomes fully formed, does (\xi)r transition back to a positive value. These phase transitions have not been observed on Au cantilevers under similar electrochemical conditions.
, Bertocci, U.
and Stafford, G.
Dynamic Stress Analysis Applied to (111)-Textured Pt in HClO_(4) Electrolyte, Journal of the Electrochemical Society, [online], https://doi.org/10.1149/2.003310jes
(Accessed December 9, 2023)