Fabrication of Hybrid Silver Microstructures from Vermiculite Templates as SERS Substrates

There is great interest in developing complex, 3D plasmonic materials with unusual structural properties. This can be achieved via template-assisted approaches exploiting scaffold elements to engineer unique plasmonic substrates, which would be otherwise impossible to synthesize. Herein, we present a novel, simple, and low-cost template-assisted method for producing interconnected 3-D silver microstructures by utilizing vermiculite, a well-known silicate, as both in-situ reductant and template for silver growth. The silicate network of the vermiculite can be easily removed by dissolution with hydrofluoric acid, which, simultaneously, leads to the formation of a magnesium fluoride skeleton supporting a plasmonically active silver film. Optical, morphological, and chemical properties of the materials were extensively investigated, revealing, for example, that hybrid silver microstructures can be exploited as valuable SERS substrates over a broad spectral range of excitation wavelengths.