Constructing high-efficiency photocatalyst for degrading ciprofloxacin: Three-dimensional visible light driven graphene based NiAlFe LDH

A three-dimensional (3D) graphene based photocatalyst, consisting of Fe(III)-doped NiAl layered double hydroxide (NiAlFe LDH), was prepared via a simple one-step hydrothermal approach for the first time. The growth of NiAlFe LDH nanoplates and the reduction of graphene oxide were accomplished simultaneously during hydrothermal process without adding toxic reductant and toxic solvent. No complex and time-consuming preparation steps were needed. The structural characterization shows that NiAlFe LDH nanoplates with a size of 100–150 nm vertically grow on the reduced graphene oxide (RGO) sheet, forming a unique 3D structured graphene based photocatalyst (NiAlFe LDH/RGO). The photocatalyst was applied for the first time to remove ciprofloxacin (CIP) in wastewater under visible-light illumination. Interestingly, after incorporating with an appropriate amount of Fe3+ and RGO, the NiAl LDH shows improved photocatalytic degradation performance in comparison with reported photocatalysts. The reaction rate in the presence of NiAlFe LDH/RGO is respectively 2.4 and 7.3 times faster than that in the presence of NiAl0.85Fe0.15 LDH and NiAl LDH, demonstrating that the addition of Fe3+ and RGO can improve synergistically the photocatalytic performance of the nanocomposite. Moreover, the photocatalytic mechanism of the 3D NiAlFe LDH/RGO photocatalyst was also investigated in detail.