Calculation Study of Conversion Nitrate Ions to N2 and O2 by Zinc Oxide Nano-Cage (Zn12O12-NC)

Abstract

The aim of this study is to investigate the performance of zinc oxide nano-cages (Zn12O12-NC) to detect and reduce nitrate (NO3-) ions from aqueous media and convert them to oxygen and nitrogen gases by the density functional theory (DFT) method on a B3LYP level with basis set of 6-31+G*. Due to the structure of the nano-cage (Zn12O12-NC), there are some location positions with different potential on it. The results showed that the first N atom of nitrate ion strongly prefers to be adsorbed on O atoms and O of nitrate ion is adsorbed on Zn atoms of the 4-membered ring (4-MR). The electronic, structure and thermodynamic properties of these conversions are calculated and investigated. The energy gap (Eg) of the Zn12O12-NC is dramatically reduced from 3.88 to 1.22 eV upon the adsorption of NO3- ion, suggesting that it is transformed to n-type semiconductor ascribed to the large charge transfer from the ion to the nano-cage and ions convert into oxygen and nitrogen on it. The data show that Zn12O12 nano-cage can be used to identify and reduce of nitrate ions from the environment and may be helpful in several fields of study such as sensors, catalysts, and field emission investigations.