“Nanocomposites and nanomaterials”

First principle study of electronic properties of ZnO nanoclusters with native point defects during gas adsorbtion
R.V. Bovhyra1, D.I. Popovych1, O.V. Bovgyra2
1 Pidstryhach Institute for Applied Problems of Mechanics and Mathematics NAS Ukraine, Naukova 3-B, Lviv, Ukraine
E-mail: bovhyra@gmail.com
2 Ivan Franko National University of Lviv, Faculty of Physics, Kyrylo and Mefodiy 8, 79005-Lviv, Ukraine

We present the results of ab initio density functional theory studies of the adsorption of molecules of different gases (O2, H2O, CO, NO2,NH3) on the surface of “magic” clusters (ZnO)n (n = 34, 60) with native point defects. Calculations were performed using ultrasoft pseudopotentials in the basis of plane waves, similar to previous studies [1]. The exchange-correlation functional is a generalized gradient approximation (GGA) proposed by Perdew, Burke and Ernzerhof. Optimization of the nanocluster structure was performed using conjugate gradient method. No symmetry restrictions were used during structure optimization.
We performed geometry optimization for a number of isomers of (ZnO)34 and (ZnO)60 nanoclusters with O and Zn vacancies, as well as, interstitials and antisites, and then the molecules of O2, H2O, CO, NO2, NH3 had been added to the surface. The calculations of electronic properties of these clusters were performed and then we compared the results with the values obtained in our previous studies for ZnO nanoclusters with defects [2].
Analysis of the obtained results showed that the molecules of H2O, CO, NO2, NH3, increase the concentration of the main charge carriers (electrons) in sensor systems, whereas molecule O2, reduce their concentration. Adsorption of molecules causes the reducing of the band gap of nanoclusters. The sharpest decrease is observed for O2 molecules, and among donor molecules the greatest impact was observed with CO and NH3 molecules. 

1.	Bovgyra O.V., Bovhyra R.V., Popovych D.I., Serednytski A.S. Ab inito study of structural and electronic properties of (ZnO)n “magical” nanoclusters n=(34, 60 // Nanoscale Research Letters.-2017.-12:76.
2.	R.Bovhyra, D.Popovych, O.Bovgyra, A.Serednytsky First principle study of native point defects in (ZnO)n nanoclusters (n = 34, 60) // Applied Nanoscience. – 2019. – 9(5). – P. 1067-1084.