Unusual adsorption behavior of hydrogen molecules on Zr-doped perfect and oxygen-vacancy defective rutile TiO_2(110) surfaces: Periodic DFT study

摘要

Adsorptions of Zr atom onto the perfect rutile TiO2(110) and the oxygen vacancy rutile TiO2 (110) ([TiO2+V-o]) to form Zr-TiO2 and Zr-[TiO2+V-o] were studied using periodic density functional theory (DFT) method. Three configurations of both Zr-TiO2 and Zr-[TiO2+V-o] surfaces were found and binding energies of Zr atom of the most stable Configurations of Zr-TiO2 and Zr-[TiO2+V-o] surfaces are respectively -3.36 and -3.26 eV. The most stable Configurations of the Zr-TiO2 and Zr-[TiO2+V-o] surfaces were selected in hydrogen adsorption study. Adsorption energies of single H-2 molecule on the most stable Zr-TiO2 and Zr-[TiO2+V-o] are -1.43 and -1.45 eV, respectively. Based on the second H-2 molecular adsorption on the hydrogen pre-adsorbed Zr-TiO2 and Zr-[TiO2+V-o] surfaces, adsorption energies of -1.90 and -2.55 eV were found, respectively. The second H-2 molecule adsorption was found to be much stronger than the first H-2 molecule adsorbed onto the Zr-TiO2 and Zr-[TiO2+V-o] surfaces by 32.9% and 75.9%, respectively. Either the Zr-TiO2 or Zr-[TiO2+V-o] surface is suggested as hydrogen-storage material and the Zr-TiO2 can be proposed as an electrical resistance-based hydrogen sensor. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.