Enhanced Charging-Induced Resistance Variations of Nanoporous Gold by Dealloying in Neutral Silver Nitrate Solution

Langmuir. 2018 Nov 6;34(44):13110-13115. doi: 10.1021/acs.langmuir.8b02082. Epub 2018 Oct 22.

Abstract

Nanoporous gold (np-Au), produced by dealloying in silver nitrate solution exhibits extraordinary high surface-to-volume ratios of more than 20 m2/g which represents an excellent prerequisite for property tuning by surface charging. Upon electrochemical charging in aqueous KOH solution, the electrical resistance is observed to vary reversibly by up to 88%. The charge coefficient, thus the sensitivity of the resistance toward the imposed charge per mol, is however significantly smaller compared to conventionally prepared np-Au, etched in nitric acid solution. While the strong resistance variation observed in the present work can directly be related to the high charge transfer due to extraordinary fine porosity, the charge coefficients can be understood with regards to the matrix resistance of the respective materials, which is strongly influenced by dealloying residuals.