Tailored TiO₂-based carbon nanotube composites for enhanced dye photodegradation

Title : Tailored TiO₂-based carbon nanotube composites for enhanced dye photodegradation

Abstract:

Composites of nitrogen-doped TiO₂ (TiO₂:N) and single-walled carbon nanotubes (SWNT), TiO₂:N/SWNT functionalized with carboxyl groups (SWNT-COOH) and TiO₂/SWNTs were prepared via solid-state interaction of the two constituents. Their structural and optical properties were characterized using X-ray diffraction (XRD), UV–VIS spectroscopy, and Raman scattering. According to XRD measurements, all composites exhibited a crystalline anatase phase. Incorporation of carbon nanotubes caused an increase in the full width at half maximum (FWHM) of the Raman band peaked at 144–146 cm⁻¹, corresponding to the Eg(1) vibrational mode of TiO₂:N and TiO₂, indicating local lattice modifications. Additionally, the band gap of TiO₂:N and TiO₂ nanoparticles decreased in the presence of SWNTs and SWNT-COOH. Photocatalytic activity of TiO₂:N/SWNT, TiO₂:N/SWNT-COOH and TiO₂/SWNT composites was evaluated by degrading rhodamine B (RhB) and rhodamine 6G (Rh6G) in aqueous solutions after UV irradiation. The results indicated that RhB photodegradation efficiency increased up to 70% with 2.5 wt.% SWNT, and up to 85% for TiO₂:N/SWNT-COOH at the same loading. For Rh6G, the highest efficiency of 85.1% was achieved with TiO₂/SWNT containing 1 wt.% well-dispersed semiconducting SWNTs. The reaction kinetics revealed that photodegradation of both dyes followed a complex three-stage first-order mechanism. These results demonstrate that nitrogen-doped TiO₂/carbon nanotube composites, particularly when functionalized with carboxyl groups, exhibit enhanced photodegradation of organic dyes through structural modification and band gap tuning, providing a promising strategy for water purification applications.

Biography:

Adelina Udrescu is a scientific researcher IIIrd degree at the National Institute of Materials Physics in Romania and holds a PhD in Physics. Her research focuses on synthesis, structural, and optical characterization of advanced nanostructured materials. She has co-authored multiple studies on composites containing carbon nanotubes and photodegradation processes, employing experimental techniques such as X-ray diffraction, Raman, and UV–VIS spectroscopy. Her interdisciplinary work spans materials engineering, spectroscopy, and she actively contributes to national and international collaborations on clean water and energy storage materials research.