Silver-doped TiO2/SnO2 for enhanced visible-light-driven photocatalytic degradation of acetaminophen

The increasing presence of pharmaceutical contaminants such as acetaminophen (ACT) in water bodies has raised concerns due to their persistence and potential risks to human and environmental health. Semiconductors such as titanium dioxide (TiO 2 ) and tin oxide (SnO 2 ) are well-established photocatalysts, but their application is limited by their large band gaps. In this work, Ag-TiO 2 /SnO 2 ternary composites were developed as visible-light-driven photocatalysts for ACT degradation. Silver nanoparticles were incorporated into TiO 2 nanofibers by electrospinning at varying concentrations (0.5, 1.5, and 3.0 wt%) to enhance visible-light absorption and improve charge separation. A conformal SnO 2 layer was then deposited by atomic layer deposition to increase charge mobility and promote strong interfacial contact. The SnO 2 layer thickness was set to 5 nm, as this amount of SnO 2 on TiO 2 nanofibers was previously reported to yield optimal performance. Photocatalytic tests showed that the sample with the highest silver content (3.0 wt%) achieved 97% removal of ACT within 180 minutes under visible light, with a degradation rate 4.66 times higher than that of the TiO 2 /SnO 2 binary composite. This enhanced performance is attributed to the synergistic combination of TiO 2 , SnO 2 , and silver, each contributing its unique properties to overcome individual limitations. Reactive species analysis identified superoxide radicals as the dominant species responsible for ACT degradation. These results demonstrate the potential of Ag-TiO 2 /SnO 2 heterostructures as efficient photocatalysts for the removal of emerging contaminants, offering a promising approach for sustainable water treatment technologies. • Ag-TiO 2 /SnO 2 composites were prepared for acetaminophen degradation under visible light. • The optimal Ag-TiO 2 /SnO 2 sample achieved 97% acetaminophen degradation in 180 minutes. • The photocatalyst demonstrated excellent stability after repeated reuse cycles. • The reactive species responsible for degradation were • O 2 - , • OH, and holes.