Layered Nanoporous Platforms for SERS Sensing

Nanoporous metals have been widely explored as platforms for plasmonic applications due to their high surface area and the strong localized electromagnetic fields they support. These properties can be tuned over a broad energy range by controlling both the metal composition and the morphology of the porous network. Until recently, most studies focused on nanoporous structures composed of a single metal, while the influence of alloyed or multi-metal systems remained largely unexplored. Only in recent years the interest in bimetallic nanoporous systems begun to grow. Combining two or more plasmonic metals provides a powerful strategy to investigate intermetallic interactions, including plasmonic coupling, charge transfer, interfacial band hybridization, and electromagnetic field interactions, as well as thermal and electronic energy transfer depending on the system geometry. Bimetallic nanoporous platforms are also highly relevant for biomolecular sensing, particularly in Surface-Enhanced Raman Scattering (SERS). In this work, we present the first detailed study of bimetallic nanoporous platforms fabricated via a dry-synthesis approach, enabling simple and controllable fabrication of layered structures combining metals such as Au, Ag, and Cu. Experimental results, supported by numerical simulations, demonstrate that these layered systems allow electromagnetic field localization at distinct energies, with synergistic effects arising from different bimetallic configurations.