Zinc oxide, ZnO is of interest in many applications as an important material with excellent combination of optical, electrical and microstructural properties. Lately, the Zno aroused a quite significant worldwide research interest owing to its photocatalysis property. Due to its nontoxicity and high photocatalytic activity, ZnO is increasingly used for the degradation of various environmental pollutants (1). Generally, the photocatalysis requires the effective adsorption of reactant molecules/ions on the surface of ZnO photocatalysts. As the adsorption states of specific molecules/ions are intrinsically determined by surface atomic structures of ZnO, the photocatalytic performance is strongly associated with the electronic structure and the shape of ZnO (2). To develop size and morphology controlled ZnO nanoparticles, synthesis route is of major importance. The starting zinc compound, synthesis procedure, chemical composition of solvent, nature of the precipitating agent, pH, temperature and time of ageing, all play an important role in understanding the mechanism of ZnO nanoparticles formation, with the pivotal emphasis put on the size and geometrical shape of ZnO particles. Particularly, in several recent papers Šarić et al. reported a strong influence of the synthesis route on the formation of ZnO nanoparticles, their size and geometrical shape (3-5).

Primary target of the proposed research is to get detailed insight into the relationship between structural, microstructural and morphological features of ZnO nanoparticles prepared: (a) solvothermally using the [Zn(acac)2·H2O] in the presence of organic additive (triethanolamines: MEA, DEA or TEA) and/or various solvent systems at 170 °C, (b) via thermal decomposition of [Zn(acac)2·H2O] (direct heating at ≥200°C). Finally, the detailed knowledge on structural features obtained from the room temperature (RT) Powder X-ray Diffraction (PXRD) and microscopy measurements (i.e Field Emission Scannning Electron Microscopy, FE-SEM) will serve as an input that will lead to establishment of a crossover towards desired photocatalytic activty of the targeted ZnO nanoparticles. The last and most demanding step will be achieved using the X-ray Absorption Spectroscopy (XAS) and X-ray photoemission spectroscopy (XPS) investigations in order to unveil the electronic structure of the synthesized ZnO nanoparticles, as the photocatalytic performances are strongly correlated with electronic structure and shape of ZnO. This will be the bottleneck that will give the output results, help to systemattically control and tune the preparation steps in order to deliver ZnO nanoparticels with the optimal photocatalytic performance estimated by the photodegradation of Rhodamine B (RhB), metil orange and metilen blue solutions. We will target the following research objectives: (i) design ZnO nanoparticles with different morphology via tuned synthetic procedures, (ii) identify the ZnO nanoparticles having the highest and optimal photocatalytic performance, (iii) develop the ZnO nanoparticles as functional materials with enhanced functionalities through the synergy of unveiled structural, electronic and photocatalytic features.

(1) M.R. Hoffmann, Chem. Rev., 1995, 95, 69; (2) R. Boppella, et al. J. Phys. Chem. C, 2013, 117, 4597; (3) A. Šarić, et al. J. Alloys Compd., 2015, 652, 9; (4) A. Šarić, et al. ChemistrySelect, 2017, 2, 10038; (5) A. Šarić, et al. J. Mol. Struct., 2019, 1178, 251.