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0Laser-based preparation of simple and complex oxide nanoparticles for photocatalytic applications
E. Fakhrutdinova*, A. Golubovskaya, A. Volokitina, O. Reutova, V. Svetlichnyi
National Research Tomsk State University, 634050 Tomsk, Russia
* fakhrutdinovaed@gmail.com
Photocatalytic technologies for the safe purification and disinfection of water, the production of environmentally friendly fuel and the conversion of biomass into useful products are among the most in demand today [1]. Therefore, the development of safe, simple and effective methods for the synthesis of photocatalytic systems with controlled characteristics is an urgent task. Along with traditional chemical approaches, methods based on high-energy exposure hold great promise in photocatalysis. The use of pulsed laser ablation (PLA) of chemically active targets in a liquid with combination additional laser treatment of colloids of focused laser radiation with the formation of plasma makes it possible to create conditions for the formation of new phases and complex defect structures that are inaccessible to chemical synthesis methods. Freshly prepared PLA colloids have high activity, which also makes it easy to obtain new highly dispersed composite materials.
In the work, PLA targets (Ti, Zn, Bi, Si) using a Nd:YAG laser (X = 1064 nm, t = 7 ns, Eimp = 150 mJ, f = 20 Hz) were obtained as simple (TiO2, ZnO), and complex oxides (Bii2SiO2o), which have high photocatalytic activity.
Dark TiO2 obtained by PLA, due to the presence of a large number of defects (oxygen vacancies/Ti3+ ions), absorbs in the visible region of the spectrum [2] and exhibits high activity in the process of photocatalytic hydrogen evolution from a water-glycerol mixture. Additional modification of dark TiO2 with metals (Pt, Cu) increases the apparent quantum yield (AQY) to 0.78 for Pt and 0.32 for Cu, respectively.
PLA ZnO also has a highly defective structure and exhibits good antibacterial activity, which increases upon irradiation due to the photogeneration of reactive oxygen species (ROS). It was found that with a minimum loading of ZnO NPs - 0.05 g/l, there is a decrease in the active growth of S. aureus bacteria in the nutrient medium and 100% death of S. aureus in the buffer medium under the soft UV (375 nm) irradiation. Under visible light (410 nm) irradiation, we achieved 100% death of bacteria within 2 hours of irradiation, and additional modification of zinc oxide with Ag NPs significantly accelerates the death of S. aureus even with a decrease in irradiation power.
The combination of PLA with laser irradiation of a mixture of colloids in plasma mode was used to obtain a complex oxide with the composition Bi^SiO20. The material contains a small amount of Bi2(CO3)O2 impurity, which is also a photocatalytically active phase. These systems are effective in the photodegradation of persistent model pollutants - Rhodamine B dye and phenol. Under LED 375 nm irradiation, in both cases, complete decomposition of the aromatic rings occurs. The resulting materials also demonstrate high stability in cyclic tests [3].
This study was supported by the Tomsk State University Development Programme (Priority-2030)
[1] R.C. Forsythe, C.P. Cox, et al, Pulsed Laser in Liquids Made Nanomaterials for Catalysis Chem. Rev. 121, 7568-7637 (2021).
[2] E.D. Fakhrutdinova, A.V. Shabalina, et al, Highly defective dark nano titanium dioxide: preparation via pulsed laser ablation and application, Materials, 13, 1-17 (2020).
[3] A.G. Golubovskaya, D.A. Goncharova, et al, Photocatalytic activity of colloidal Bi-Si-based nanoparticles prepared by laser synthesis in liquid Mater Chem and Phys. 314, 128800 (2024).
