Photoluminescence and photocatalytic activity of flowerlike hierarchical TiO₂:Sm³⁺ microspheres

Graphical abstract: Flowerlike hierarchical TiO₂:Sm³⁺ microspheres were successfully prepared via a solvothermal method. The crystalline size decreased with increasing Sm³⁺ concentration. Each TiO₂:Sm³⁺ microsphere consists of several dozen nanopetals, which are composed of several aggregated nanothorns. Under 290, 360, 362, and 368 nm excitation, the ⁴G_5/2 → ⁶H_5/2, ⁴G_5/2 → ⁶H_7/2, and ⁴G_5/2 → ⁶H_9/2 transitions were observed. The luminescence intensity increased with increasing Sm³⁺ concentration, up to about 1.5 mol%, and then decreased abruptly. In addition to the aforementioned photoluminescence properties, TiO₂:Sm³⁺ microspheres can present photocatalytic activity for the degradation of RhB. - Highlights: • Flowerlike hierarchical TiO₂:Sm³⁺ microspheres were synthesized by a solvothermal method. • TiO₂:Sm³⁺ microspheres can present photocatalytic activity for the degradation of RhB. • The optical properties of TiO₂:Sm³⁺ microspheres with different Sm³⁺ concentration were studied in detail. - Abstract: Flowerlike hierarchical TiO₂:Sm³⁺ microspheres were successfully prepared via a solvothermal method. The results of the X-ray diffraction measurements revealed that the TiO₂:Sm³⁺ microspheres were anatase phase. The crystalline size of microspheres decreased with increasing Sm³⁺ concentrations. Each TiO₂:Sm³⁺ microsphere consists of several dozen nanopetals, which are composed of several aggregated nanothorns. Under 290, 360, 362, and 368 nm excitation, the ⁴G_5/2 → ⁶H_5/2, ⁴G_5/2 → ⁶H_7/2, and ⁴G_5/2 → ⁶H_9/2 transitions were observed. The luminescence intensity increased with increasing Sm³⁺ concentration, up to about 1.5 mol%, and then decreased abruptly. The peak positions and the shape of emissions were independent of Sm³⁺ concentrations. In addition to the aforementioned photoluminescence properties, TiO₂:Sm³⁺ microspheres can possess superior photocatalytic activity for the degradation of RhB. In addition, the BET surface areas increased with increasing Sm³⁺ concentrations, which should be benefit for RhB adsorption