Enhanced photoactivity performance of CeO2 and CuO modified TiO2 nanotube arrays

Abstract

TiO₂ nanotube arrays (TiO₂-NT) were synthesized by electrochemical anodization and modified with 1, 3 and 5 mM Ce(III) or Cu(II) by chemical deposition. The catalysts were characterized by scanning electron microscopy, X-ray diffraction, AFM analysis, and electrochemical techniques. The presence of Ce and Cu species was confirmed by slight shifts in the main TiO₂ diffraction peaks, suggesting the incorporation of Ce and Cu into the TiO₂ lattice, since some characteristic peaks of these oxides overlap with those of the predominant anatase phase. The catalyst samples displayed a well-defined morphology, with a nanotube length of 8.5–10.1 μm and an average NT-TiO₂ internal diameter of 54–112 nm. Higher anodic oxidation photocurrent densities were obtained compared to the unmodified TiO₂ sample, such as 340 μA/cm² for CeO₂-TiO₂-NT, 315 μA/cm² for CuO-TiO₂-NT and 60 μA/cm² for TiO₂-NT under UV at the highest metal oxide concentration. Furthermore, 5 mM-CeO₂-TiO₂-NT showed good stability during reuse, without appreciable deactivation of its photocatalytic performance. The photocatalytic performance of the catalyst samples was studied by the degradation of acetaminophen (AC) at neutral pH. The degradation of AC under UV and sunlight increased with increasing metal oxide concentration in the TiO₂ nanostructure. Complete AC degradation was achieved with ≤ 50 µmol L⁻¹ AC at ≤ 75 min.