Designing of surface chemical enhanced Raman AgCu and AuCu clusters: Density functional theory

Abstract

Designing of surface-enhanced Raman material with low cost and high enhancement ability become animportant research direction in the field of surface-enhanced Raman scattering. In this paper, the density functional theory calculations were utilized to investigated the Raman performances of stabled CuAg and CuAu clusters for 4-NBT probe molecule. Some suitable alloying designs in atomic level were found to reduce cost and enhance Raman signal of noble nanoparticles, such as, a small quantity introduction of Cu element into the tip of Ag nanoparticle surface and the core–shell structure. The designed Cu2Ag2, Cu1Ag12, Cu1Au12, Cu3Ag10, Cu3Au10, Cu14Ag9, Cu4Au9, Cu9Au4 and Cu10Au3 clusters exhibited enhanced Raman diffraction peak intensity beyond 11.0% compared to the 4-NBT molecule on the Ag4, Ag13 and Au13 clusters. This strategy could be applied to designing noble metal based surface-enhanced Raman materials with low cost and high enhancement ability by adjusting the atom site in atomic level.