From a fundamental materials perspective, Ag has the largest cross-section for visible light plasmonic interaction and amongst the highest surface enhanced Raman signal enhancement, even more so then Au. However, despite the fact that Ag is considered a noble metal, its surface oxidizes relatively quickly with exposure to ambient air. This degradation is deleterious to applications like surface enhanced Raman scattering (SERS) and surface plasmon resonance (SPR) sensing. Here we show that oxidation of Ag nanoparticles under ambient conditions can be significantly suppressed by contacting Ag with immiscible Co nanoparticles. We attribute this oxidation-resistance to a nanoscale galvanic coupling effect. Ag-Co bimetallic nanoparticle arrays prepared by pulsed laser dewetting self-organization have a sensitivity towards localized plasmon resonance sensing that is comparable to pure Ag but with significantly enhanced stability that ensures high sensitivity even after six months of storage in air.

Oxidation-resistant Ag nanostructures for ultrastable plasmonic applications

245th National Meeting (2013)

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