Effects of electrolytes on the fabrication of three-dimensional nanoporous gold films by a rapid anodic potential step method for SERS

A unique one-step anodic potential step strategy has been developed recently by our group to fabricate a three-dimensional (3D) nanoporous gold film (NPGF) within 1 min as an efficient surface-enhanced Raman scattering (SERS) active substrate. Gloria et al. (J. Electroanal. Chem. 2011, 656, 114119) demonstrated that the prepared NPGF under optimum conditions (2?M HCl, 50?s) has higher SERS intensities than that of a commercial single-use gold substrate. However, the SERS performance of 3D NPGFs fabricated in neutral KCl by this strategy have not been investigated. In this paper, SERS performances of the NPGFs fabricated in electrolytes of KCl and HCl are compared for the first time, using pyridine as a test molecule. Equivalent SERS intensities can be obtained on the 3D NPGFs prepared in these two electrolytes under respectively optimum conditions. The results suggest that hot spots of nanogaps and crevices because of the aggregation/coalescence of gold nanoparticles and the formation/removal of thin gold oxide coatings contribute greatly to the high SERS activity. Copyright (c) 2012 John Wiley & Sons, Ltd.