Cd-doped Ag(2)O/BiVO(4) visible light Z-scheme photocatalyst for efficient ciprofloxacin degradation

Foreign element doping can produce new photocatalysts with different band edge positions and adsorption properties. A composite of such a doped semiconductor with another component should enhance its photocatalytic properties towards a target substrate. The present investigation used a simple hydrothermal protocol to prepare Cd-doped Ag(2)O nanoparticles. The Cd-doping of Ag(2)O nanoparticles changed its valence band maximum position from 0.8 eV (for undoped Ag(2)O nanoparticles) to 2.67 eV with a slight narrowing of the Ag(2)O bandgap. A combination of DFT calculation and XRD results showed that the dopant Cd substituted Ag in the Ag(2)O lattice. The doped material is an effective photocatalyst for ciprofloxacin degradation but with poor recyclability. The joining of a BiVO(4) part to the Cd-doped Ag(2)O nanostructures gave a composite with improved photocatalytic activity and recyclability towards ciprofloxacin degradation. DFT calculations showed that BiVO(4) has a higher oxygen affinity than Cd-doped Ag(2)O. The XPS characterization of the composite and appropriate active species scavenger experiments demonstrated a Z-scheme mechanism. Superoxide radicals play a critical role in CIP degradation.