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 O nanoparticles. The Cd-doping of Ag O nanoparticles changed its valence band maximum position from 0.8 eV (for undoped Ag O nanoparticles) to 2.67 eV with a slight narrowing of the Ag O bandgap. A combination of DFT calculation and XRD results showed that the dopant Cd substituted Ag in the Ag O lattice. The doped material is an effective photocatalyst for ciprofloxacin degradation but with poor recyclability. The joining of a BiVO part to the Cd-doped Ag O nanostructures gave a composite with improved photocatalytic activity and recyclability towards ciprofloxacin degradation. DFT calculations showed that BiVO has a higher oxygen affinity than Cd-doped Ag 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.