C-isolated Ag–C–Co sandwich sphere-nanostructures and their high activity catalysis induced by surface plasmon resonance

Magnetic C-isolated Ag-C-Co sandwich sphere nanostructures have been fabricated through a synchronous growth and assembly process, in which the outer Co sphere-shells assemble around the surface of synchronously grown Ag-C sphere-cores. Raman and UV-vis absorption spectroscopy studies show that the covering of Co shell on Ag-C sphere cores weakens the surface-enhanced Raman scattering (SERS) and surface plasmon resonance (SPR) of Ag-C sphere cores. Owing to its ferromagnetic behaviour, the as-prepared C-isolated Ag-C-Co sandwich nanospheres can be easily separated and recycled by an external magnet field for application. Compared with Ag-Co, C-Co, and Co nanospheres of the same size, the resultant magnetic Ag-C-Co sandwich nanospheres exhibit markedly high catalytic activity toward ammonia borane hydrolytic dehydrogenation at atmospheric pressure and room temperature, which is induced by SPR from C-isolated sandwich structural and electronic synergistic effects.