pH-Engineered Tm³⁺/Yb³⁺ Co-Doped TiO₂: Morphological and Structural Properties Transformation and Photocatalytic Degradation Activity Performance
DOI:
https://doi.org/10.48048/tis.2025.10238Keywords:
Rare earth, Photocatalytic degradation, Anatase-brookite, Sol-gel, TiO2Abstract
Thulium (Tm³⁺) and ytterbium (Yb³⁺) co-doping in TiO₂ has garnered considerable interest among RE dopants because of their distinctive optical characteristics. In this present study, Tm3+/Yb3+ co-doped TiO2 powder was prepared using the sol-gel method by varying pH values (4, 6, 8, and 10). The morphological and structural properties of Tm3+/Yb3+ co-doped TiO2 were analyzed. The photocatalytic performance of the Tm3+/Yb3+ co-doped TiO2 was evaluated in methylene blue (MB) degradation under UV light irradiation. The mixed phase of anatase-brookite was discovered in an acidic medium, while pure anatase was observed at higher pH values. As pH increases, the average crystallite size decreases, and this can be related to the hydrolysis-condensation reactions. FESEM images showed that all samples demonstrate the formation of spherical granules. According to the FTIR analysis, the rising pH value induces a change in Ti-O stretching vibrations towards a lower wavenumber, attributable to the transition of phase from a mixed anatase-brookite to a pure anatase phase. Sample pH 4 exhibited the highest rate constant and photocatalytic degradation percentage because it is a mixed anatase-brookite phase. This enhancement primarily arises from the synergistic effect between the 2 phases. Optimizing the pH during synthesis is critical for tailoring the morphological and structural properties of Tm³⁺/Yb³⁺ co-doped TiO₂, ultimately improving their photocatalytic efficiency and practical applicability in environmental and energy-related fields.
HIGHLIGHTS
- The mixed phase of anatase-brookite was discovered in an acidic medium, while pure anatase was observed at higher pH values.
- As pH increases, the average crystallite size decreases, and this can be related to the hydrolysis-condensation reactions.
- FESEM images showed that all samples demonstrate the formation of spherical granules.
- pH 4 shows the highest photocatalytic degradation percentage and rate constant because it is a mixed anatase-brookite phase. This enhancement primarily arises from the synergistic effect between the 2 phases.
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