Investigating the temperature and Al doping effect on the O2 adsorption Process on ZnO nanowire surface: A ReaxFF-MD approach

W Ftahi and N AL-Shaeri and YW Yang and AS Ahmed and YL Tang and QX Liu and YX Ni, COMPUTATIONAL MATERIALS SCIENCE, 252, 113774 (2025).

DOI: 10.1016/j.commatsci.2025.113774

ZnO nanostructures have garnered significant attention from researchers and industries due to their outstanding properties as gas-sensing materials. Aluminium (Al) doping, in particular, can further fine-tune or optimize these gas-sensing properties. In this research, we investigate the adsorption of O2 molecules on undoped and Al-doped ZnO nanowires at 5% and 10% doping concentrations using advanced reactive force field (ReaxFF)based molecular dynamics (MD) simulations. The adsorption process is studied at temperatures of 100 K, 300 K, and 500 K, with 300 O2 molecules in each case, and the influences of these factors on the adsorption type are analyzed through radial distribution function (RDF) analysis. The adsorption behavior of O2 molecules on both undoped and Al-doped ZnO nanowires is compared by calculating system energy, adsorption energy, and the number of adsorbed molecules. The results show that the binding distances between O2 molecules and Zn and Al atoms on the nanowire surfaces are 2.18 & Aring; and 1.78 & Aring;, respectively, as determined from RDF analysis. The O2 adsorption process on undoped and Al-doped ZnO nanowire surfaces occurs in two distinct stages, with higher temperatures leading to an increased number of adsorbed molecules. As Al doping increases, it significantly accelerates O2 adsorption in the initial stage, while pure ZnO shows greater adsorption number in the second stage. Chemisorption dominates the interaction in both undoped and Al-doped ZnO.

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