Highly adsorbent Ca2+/La3+ doped TiO2 quantum dots for tetracycline degradation under visible light

In this study, titanium dioxide quantum dots (TiO2 QDs) were synthesized and doped with 0–5 mol% Ca2+ and La3+ via hydrolysis of titanium tetraisopropoxide and hydrothermal microwave treatment at 120 °C for 10 min. As a result, the Ca2+/La3+ doped TiO2 QDs presented a crystallite size of ∼5 nm, estimated by the Scherrer equation. The samples with 1 mol% Ca2+ showed a high BET surface area (412.19 m2 g−1) and an increase of the interfacial component (64%) led to a highly energetic and adsorptive QDs surface. XRD and Raman analyses showed anatase as the main crystal phase. A red shift in the Raman spectrum induced a rise in the oxygen vacancies formation. The band gap of the QDs was calculated by the Tauc Plout method, which reached values of 2.72 eV, in the case of doping with 1 mol% of Ca+2. Finally, the degradation of 96% tetracycline in 30 min of photocatalysis using the Ca2+/La3+ doped TiO2 QDs was reached under visible light.