Tuning the redox potential of Ag@Ag2O/WO3 and Ag@Ag2S/WO3 photocatalysts toward diclofenac oxidation and nitrophenol reduction

WO3 nanoplates modified with either Ag2O or Ag2S nano-architectures were synthesized by a depositionhydrothermal route (180 degrees C for 5 h). They were characterized using X-ray powder diffraction, N-2 sorptiometry, Transmission electron microscopy, UV-vis diffuse reflectance spectroscopy, Photoluminescence spectroscopy, and X-ray photoelectron spectroscopy. The photo-catalytic (lambda > 420 nm, 160 W) degradation of Diclofenac (DCF; 60 mg/l), was achieved using H2O2 (1 x 10(-4) M) with either Ag@Ag2O/WO3 (K = 32.0 x 10(-3) min(-1)) or Ag@Ag2S/WO3 (K = 7.3 x 10(-3) min(-1)) catalysts. In the case of DCF degradation using radical scavengers, O-center dot(2)- played a key role in the degradation process whilst (OH)-O-center dot and holes acted moderately minor roles. The possible DCF degradation paths and intermediates were assessed by LC-MS. Both Ag@Ag2O/WO3 and Ag@Ag2S/WO3 catalysts were used in the photo-reduction of 4-nitrophenol (4-NP; 1.8 x 10(-4) M) to 4-aminophenol (4-AP) with rate constants equal 8.3 x 10(3) min(-1) and 1.6 x 10(-3) min(-1), respectively.

Automated summary

WO3 nanoplates modified with Ag2O or Ag2S were synthesized via a deposition-hydrothermal route for photocatalytic degradation of Diclofenac and 4-nitrophenol. The study evaluated the degradation pathways and intermediates, showing that the catalysts exhibited different reaction rates for the degradation of Diclofenac and 4-nitrophenol.