(111)-facet dominant ultrafine nanoporous silver as SERS substrates with high sensitivities and ultrahigh detection limits

Abstract (111)-facet dominant nanoporous Ag (ONP-Ag@-0.5 V) has been fabricated by electrochemical dealloying of Ag20Zn80 precursor alloys composed of e-AgZn3 single phase in 0.5 M KOH solution at applied potential of -0.5 V. The ONP-Ag@-0.5 V has a finer nanoporous structure with an average pore size of 16 nm and the specific surface area of 13.0 m2 g-1. The Surface-enhanced Raman scattering (SERS) activity of the ONP-Ag@-0.5 V for Rhodamine 6G (R6G) Raman probe is evaluated to be with a SERS enhancement factor of 2.53×1010 and limit of SERS detection of 4.8×10-14 M. The superior SERS activities mainly arise from the local electromagnetic enhancement effects of ultrafine (111)-facet dominant nanoporous structure and the narrow ligaments, the edge effects from co-distribution of Ag bumps, the plasmonic effect of the embedded ZnO, as well as the chemical enhancement of (111)-facet adsorption of more R6G molecules.