Efficient photocatalytic degradation of toxic dyes over BiFeO3/CdS/rGO nanocomposite under visible light irradiation

New magnetically separable BiFeO3/CdS/rGO heterostructures were synthesized by a facile hydrothermal method. The photodegradation processes of two textile dyes, methylene blue (MB) and methyl orange (MO), in the presence of BiFeO3/CdS/rGO heterostructures using visible light irradiation were studied. The effects of three experimental parameters including solution pH, initial dye concentration, and the catalyst dose on the removal of dyes were investigated. The optimized photocatalyst, i.e. BiFeO3/CdS(9)/rGO(4%) composite shows 92% pho-todegradation of MB and 89% photodegradation of MO after 90 min of visible light illumination, which were found to be about 4.5 times that of pure BiFeO3. The hybridisation of BiFeO with CdS can significantly inhibit the recombination of electron-hole pairs in the BiFeO3/CdS/rGO composites and the presence of rGO sheets can reduce electron-hole pairs recombination by acting as electron acceptor and electron transporter. Furthermore, the sheets of rGO can delay aggregation of nanoparticles. No obvious catalytic activity decrement can be seen after five photodegradation processes, that show the high structural stability of BiFeO3/CdS/rGO. In addition, a possible mechanism for the photocatalytic degradation process under visible-light illumination was proposed.