Design strategies of highly efficient silver/gold bimetallic arrays for SERS sensing applications

Surface Enhanced Raman Spectroscopy (SERS) offers great opportunities for the rapid and ultrasensitive detection of chemical or biological species. The success of SERS sensors primarily depends on the facile and efficient immobilization strategies of metal nanostructures on appropriate supports. Hybrid plasmonic nanostructures have attracted enormous attention due to synergetic localized surface plasmon resonance effects leading to superior SERS enhancement. Herein, we attempted to fabricate silver/gold bimetallic nanostructures using the electroless method. While the silver deposition time remained constant at 30 s, the gold immersion time varied from 10 to 50 s. The structural, optical, and morphological properties were studied using X-ray diffraction, UV-visible spectroscopy, and field emission scanning electron microscopy. The surface morphology of the bimetallic sensor showed that highly homogenous and wellorganized nanoparticles have been developed on the silicon surface. The optical properties have been well correlated to SERS activities of the sensor. SERS investigation has shown that the developed sensor demonstrated high efficiency and excellent reproducibility. The enhancement factor (EF) of 5 ×107 has also been estimated for the developed sensor. The current study emphasized the importance of bimetallic AgAu sensors as chemo-sensors for environmental remediation applications.