Fast synthesis of bimetallic Cu-Ag heterogeneous dendrites with synergistic enhancement performance for SERS detection of multiple contaminants

Heterogeneous bimetallic materials have attracted widespread concern in surface-enhanced Raman scattering (SERS) since the interactive coupling between these heterogeneous zones produces a synergistic enhancement effect. Developing a quick and easy method to prepapre bimetallic materials with superior SERS properties is therefore very important. A novel approach of electrodeposition followed by the galvanic replacement reaction (GRR) was proposed for fast fabricating copper-silver bimetallic heterogeneous dendrites on nickel foam (Cu-Ag dendrites@NF) as a stable SERS substrate. The morphology and compositions of the dendritic structure were well characterized by SEM, and XPS imaging provided a micro-area composition analysis. The metallic Cu-Ag dendrites exhibited better SERS enhancement performance than the pure metal, with an enhancement factor of 37 times that of the pure Ag cubes@NF, and 6 times that of the Ag dendrites@NF. The reason is that both the synergistic effect of plasmon coupling from bimetal Cu-Ag and the dendritic structure with large surface area and cusps contributed to electromagnetic enhancement. The substrate was successfully used for the detection of pesticide thiram, dye molecule crystal violet (CV), and toxic aromatic amines p-Aminoazobenzene (pAAB), with limits of detection (LODs) down to 10 −8 M, 10 −9 M, and 10 −8 M, respectively. This method provides a novel fast approach to fabricate a bimetallic substrate with high SERS activity, and may have broad applications in food analysis and environment monitoring.