Facile synthesis of mesoporous BiFeO_3/graphene nanocomposites as highly photoactive under visible light

摘要

In this contribution, mesoporous BiFeO3/graphene nanocomposites at varying BiFeO3 contents (0-20%) have been fabricated, and their photocatalytic performances were assessed for cipmfloxacin (CIP) photooxidation under visible light illumination. Mesoporous BiFeO3 nanoparticles were uniformly incorporated in graphene nanosheets with spherical-like morphology (30 nm-50 nm). The mesopomus BiFeO3 nanoparticles exhibited high pore volumes and large surface areas of 0.16 cm(3) g(-1)- and 150 m(2) g(-1)-, respectively; they were boosted to 0.20 cm(3) g(-1)- and 166 m(2) g(-1)- for BiFeO3/graphene. The observed magnetization value of mesoporous BiFeO3 nanoparticles about 1.56 emu g(-1)- was similar to five times higher than that previously published. The photocatalytic efficiencies of 5, 10, 15 and 20% BiFeO3/graphene nanocomposites were measured to be 70.4%, 88.2%, 96.2% and 98.8%, respectively, within 120 min illumination whereas the pure BiFeO3 nanoparticles were 50%. The apparent rate constant of 20% BiFeO3/graphene nanocomposite is greater similar to 4 times than that pure mesoporous BiFeO3 nanoparticles. The photodegradation rate of CIP over mesoporous BiFeO3/graphene was two times greater than that for pure mesoporous BiFeO3 nanoparticles, which is explained by the joint effects of covalent bonding and regulated band gap between mesoporous BiFeO3 and graphene. The magnetic separation of BiFeO3/graphene photocatalyst exhibits a very appropriate avenue to recover BiFeO3/graphene photocatalyst by employing a convenient magnetic field. The synthesized BiFeO3/graphene photocatalyst has excellent potential for practical applications with well recyclable and stability performance. The enhancement of BiFeO3/graphene was confirmed by measuring the photoluminescence, photocurrent and the magnetic properties.