One minute ultrasound-assisted gold and platinum-decorated ZnO photocatalyst for ibuprofen degradation.

The occurrence of ibuprofen in surface and wastewater is an emerging environmental concern due to its incomplete removal in conventional water treatment systems. In this work, ZnO-based hybrid photocatalysts decorated with noble metal nanoparticles (ZnO@Au and ZnO@Pt) were prepared through an ultrasound-assisted functionalization of preformed ZnO microstructures and evaluated for the photocatalytic degradation of ibuprofen in water. Structural, morphological, and optical characterization confirmed that the noble metal decoration preserved the wurtzite ZnO structure and the flower-like nanosheet morphology, while producing negligible changes in the optical band gap. Noble metal decoration significantly enhanced the photocatalytic activity of ZnO, with ZnO@Pt exhibiting the highest degradation efficiency under UV irradiation. After 90 min, ZnO@Pt achieved 90.2% ibuprofen degradation, compared with 36.1% and 8.9% for ZnO@Au and pristine ZnO, respectively. In addition, ZnO@Pt showed an apparent pseudo-first-order rate constant on the order of 10-2 min-1, approximately one and two orders of magnitude higher than those of ZnO@Au and bare ZnO, respectively. The improved photocatalytic performance may be related to a more efficient charge separation promoted by Pt nanoparticles. ZnO@Pt also retained significant activity in a more complex mineral water matrix despite the presence of competing inorganic species and natural organic matter. Overall, the results suggest that ultrasound-assisted noble metal decoration is a simple and environmentally friendly strategy to improve the photocatalytic performance of ZnO-based materials for water treatment applications involving pharmaceutical pollutants.