Surface-enhanced raman scattering of silver@nanoporous copper core-shell composites synthesized by an in situ sacrificial template approach

We have successfully developed a silver@nanoporous copper (Ag@NPC) core-shell nanostructure with open and bicontinuous porosity via a facile in situ hydrometallurgy route. The silver shells with a tunable thickness can be deposited on the ligament surfaces of NPC by displacing and sacrificing copper atoms. It is found that the additives of ammonia and PVP molecules play an important role in controlling the formation kinetics of Ag shells and in retaining three-dimensional nanoporosity during the displacement reaction. The resultant porous nanocomposites exhibit a dramatically improved SERS effect compared with that of the as-prepared NPC, and the enhancement factor strongly depends on the reaction time and Ag shell thickness. This study has significant implications in surface functionalization of nanoporous metals and in developing economic SERS substrates for ultrasensitive instrumentation.