Size effect on oxygen vacancy formation and gaseous adsorption in ZnO nanocrystallites for gas sensors: a first principle calculation study

Abstract

The first principle calculation based on density function theory was used to investigate the crystallite size effect of ZnO semiconductor, the size of which was controlled from 0.325 to 1.625 nm. The formation energy of oxygen vacancy increased from 3.855 to 6.256 eV, showing incremental difficulties in the formation of defects. The densities of states of ZnO super cells with complete and defective ( 110) surface were calculated, concluding positive dependences of carrier mobility and conductivity on crystallite size. The oxygen species of O − and O 2 − were considered as adsorbates on ZnO super cells with defective (110) surface. In case of crystallite size below 1.3 nm, the adsorption energy of O − increased with crystallite size, while the one of O 2 − kept constant, inferring that the oxygen adsorption was dominated by O − . A competitive adsorption between both species was found when crystallite size was over 1.3 nm. The adsorption of O − was inhibited by the incremental adsorption energy of O 2 − , which was the dominated species on ZnO crystallite surface.

Three-dimensional Ni foam supported NiCoO2@Co3O4 nanowire-on-nanosheet arrays with rich oxygen vacancies as superior bifunctional catalytic electrodes for overall water splitting

“…The relatively insufficient number of growth units compared to that of seeds will result in ultrathin Co 3 O 4 precursor nanowires, which easily leads to production of numerous oxygen vacancies in the Co 3 O 4 nanowires after calcination. 52,53 The number of growth units may also be not large enough to heal the structural defects formed during the ultrafast growth, further increasing the possibility to form oxygen defects in the final product. 52,54 OER and HER catalytic activities of NF@NiCoO 2 NSA@Co 3 O 4 NWA…”

Effects of Vacancy Defects and the Adsorption of Toxic Gas Molecules on Electronic, Magnetic, and Adsorptive Properties of g−ZnO: A First-Principles Study

“…Zinc Oxide (ZnO) has various dimensional anamorphs, such as zero-dimensional nanocrystals [1], one-dimensional nanowires [2], and two-dimensional (2D) nanofilms [3,4], which has a direct bandgap with the value of 3.37 eV [5,6]. In particular, 2D ZnO possesses high chemical or thermal stability [7][8][9], which is essential in the fields of gas detector devices [10,11], high-efficiency UV laser emitter devices at room temperature [12,13], etc. Therefore, 2D ZnO is rapidly becoming a recent research hotspot [14].…”