Ordered mesoporous silver superstructures with SERS hot spots.

We have developed a method to fabricate freestanding highly ordered porous silver (Ag) superstructures by an "assembly-based nanoparticle (NP) coalescence" method. The synthesized superstructures have high-density mesopores periodically distributed over the entire structure, on which a highly enhanced electromagnetic field was observed by electron energy loss spectroscopy. Thus, the surface enhanced Raman scattering (SERS) signal of Rhodamine 6G in the ordered mesopores is 8.2 times higher compared to that in disordered porous superstructures. The results demonstrate that these freestanding mesoporous Ag superstructures are potentially good SERS substrates.