A facile synthesis of Cu2O/SiO2and Cu/SiO2core–shell octahedral nanocomposites

We report here a simple approach to the synthesis of Cu2O/SiO2 core–shell nanocomposites in water solution. The Cu2O cores have a perfect octahedral structure with uniform size of about 200–300 nm. A compact SiO2 shell 9 nm in thickness is located at the surfaces of Cu2O octahedra, and it is composed of fine SiO2 nanoparticles. During the depositing of the SiO2 particles, as we presumed, dynamic absorbing and disengaging of Na+ at the interface of Cu2O octahedra and the solution made it possible for the formation of Cu–O–Si bonds between core and shell in the composites. The existence of Cu–O–Si bonds in our core–shell composite can be substantiated by peak changes at 1236 and 1080 cm−1 in the FT-IR spectra. This is the reason why the SiO2 shell is so compact and uniform. Moreover, these Cu2O/SiO2 core–shell octahedra were further used as precursors, depending on a simple disproportionation reaction of Cu2O in acid, to easily achieve Cu/SiO2 movable multicore–shell octahedral nanocomposites. In the final Cu/SiO2 core–shell composite, the thin SiO2 octahedral shell was held, inside of which formed several free Cu nanoparticles 50–80 nm in size. Studies on the Cu2O/SiO2 core–shell octahedral composites and Cu/SiO2 movable multicore–shell octahedral nanocomposites would be a good thing not only for fundamental research but also for applications.