Articulo
STM-SEM and impedance characterization of columnar structured gold electrodes
Autor
Gómez, M. M.
Vázquez, L.
Salvarezza, Roberto Carlos
Vara, J. M.
Arvia, Alejandro Jorge
Institución
Resumen
The impedance spectra of thin gold electrodeposits with 10<sup>−6</sup>−10<sup>−5</sup> cm average columnar radius and 4×10<sup>−6</sup>−3×10<sup>−4</sup> cm average height have been measured in acid solutions. Frequency dispersion has been observed for film thicknesses greater than 3 × 10<sup>−5</sup> cm and electrolyte resistivities larger than 300 Ω cm<sup>−1</sup>. STM-SEM observations reveal a self-affine surface structure with a size distribution of pores ranging from 10<sup>−6</sup> to 10<sup>−4</sup> cm between the columnar elements. In diluted solutions the contribution of the smallest pores to the sampled electrode area decreases as ω increases explaining the observed frequency dispersion. This result confirms that self-affine surfaces exhibit a fractional-power-law impedance. However, no simple correlation was found between the α value and the D value of the self-affine surface measured by an independent method. The present results also show that the electrolyte resistivity plays a certain role in determining the α value. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas