Highly visible-light-responsive Cu 2 O/rGO decorated with Fe 3 O 4 @SiO 2 nanoparticles as a magnetically recyclable photocatalyst.

The rhombic dodecahedral cuprous oxide-reduced graphene oxide/core-shell Fe3 O4 @SiO2 composites (denoted as rCu2 O-rGO/Fe3 O4 @SiO2 ) are successfully synthesized facilely via a wet-chemical route. The resulting rCu2 O-rGO/Fe3 O4 @SiO2 combines the unique structure of Cu2 O, electronic characteristics of reduced graphene oxide (rGO) and magnetic property of Fe3 O4 @SiO2 to be an effective and recoverable photocatalyst for the degradation of methyl orange (MO). The obtained results show that rCu2 O-rGO/Fe3 O4 @SiO2 is capable of completely degrading MO in the presence of a very low catalyst concentration (0.125 g l-1 ) within a short time (60 min) under visible light compared to the reported catalysts. The observations may be due to the distinctive interfacial structures of rhombic dodecahedral Cu2 O nanoparticles connected to rGO sheets that can enhance the separation of photogenerated electron-hole pairs, stabilize the Cu2 O and increase MO adsorption, as evidenced by a variety of spectroscopic analyses (transmission electron microscopy, x-ray photoelectron spectroscopy and photoluminescence). More importantly, these efficient photocatalysts can easily be recovered under a magnetic field and remain highly photoactive towards the degradation of MO after cyclic tests, and may be promising photocatalysts for practical applications in the solar-energy purification of wastewater.