Stabilization Of Plasmonic Silver Nanostructures With Ultrathin Oxide Coatings Formed Using Atomic Layer Deposition

Even though performance metrics position silver as the preeminent plasmonic material in the visible and near-infrared regions of the electromagnetic spectrum, it remains underutilized in applications because its properties irreversibly degrade in the environments it must operate. The emergence of shell-isolated plasmonic nanostructures as a distinct class of nanomaterials has, however, created new opportunities for the utilization of silver because its vulnerable surfaces can be encapsulated in a chemically robust transparent shell while maintaining important plasmonic properties. To fully capitalize on this opportunity requires that shell-nanostructure combinations be rationally designed where consideration is given to a parameter space encompassing nanostructure stability-property relationships. Herein, we demonstrate the layer-by-layer deposition capabilities of the atomic layer deposition (ALD) technique as a means to design shell-isolated silver nanostructures where the confined structure acts as a built-in plasmonic sensor for spectroscopically evaluating durability in air, water, and chemically aggressive environments. For all cases, appropriately designed oxide shells are shown to provide long-term stability, but where their own surface chemistry and structural integrity become limiting factors in bolstering and preserving plasmonic properties. The work, therefore, forwards the use of ALD-deposited layers for the realization of shell-isolated plasmonic nanostructures that exploit the remarkable properties of silver.