TiO2/SnO2 photocatalysts by electrospinning and atomic layer deposition for pharmaceutical contaminant removal

Abstract

Advanced technologies, including photocatalysis, are required to address the increasing global need for clean water. Titanium dioxide (TiO2) is often used as a photocatalyst for pollutant removal, but its performance is hampered by its large band gap and fast charge carrier recombination. This study describes the synthesis, characterization, and photocatalytic performance of TiO2/tin oxide (SnO2) core-shell nanofibers for the degradation of acetaminophen (ACT), a persistent pharmaceutical pollutant. TiO2 nanofibers, fabricated by electrospinning, were coated with thin SnO2 films by atomic layer deposition (ALD). After their structural, morphological, and chemical characterization, TiO2 and TiO2/SnO2 composites were tested as photocatalysts to degrade ACT under UV light. Within 40 min, 99.8 % and 70 % of ACT was degraded in the presence of the optimal TiO2/SnO2 composite (SnO2 layer thickness of 5 nm) and of TiO2 nanofibers, respectively. Moreover, the optimal TiO2/SnO2 composite showed excellent recyclability and stability over five consecutive cycles. Hydroxyl radicals (•OH), superoxide anions (•O2−), and holes (h+) were the main reactive species implicated in ACT removal. Density functional theory (DFT) modeling confirmed that the band alignment between TiO2 and SnO2 enhanced charge separation. This study demonstrates that TiO2/SnO2 is a promising photocatalyst for removing pharmaceutical contaminants from the environment.

Keywords

• Acetaminophen
• ALD
• Electrospinning
• Photocatalysis
• TiO2
• SnO2