Unusual adsorption behavior of hydrogen molecules on Zr–doped perfect and oxygen–vacancy defective rutile TiO2(110) surfaces: Periodic DFT study

Abstract

Adsorptions of Zr atom onto the perfect rutile TiO2(110) and the oxygen vacancy rutile TiO2 (110) ([TiO2+Vo]) to form Zr–TiO2 and Zr‒[TiO2+Vo] were studied using periodic density functional theory (DFT) method. Three configurations of both Zr–TiO2 and Zr‒[TiO2+Vo] surfaces were found and binding energies of Zr atom of the most stable Configurations of Zr–TiO2 and Zr‒[TiO2+Vo] surfaces are respectively −3.36 and −3.26 eV. The most stable Configurations of the Zr–TiO2 and Zr‒[TiO2+Vo] surfaces were selected in hydrogen adsorption study. Adsorption energies of single H2 molecule on the most stable Zr–TiO2 and Zr‒[TiO2+Vo] are −1.43 and −1.45 eV, respectively. Based on the second H2 molecular adsorption on the hydrogen pre‒adsorbed Zr–TiO2 and Zr‒[TiO2+Vo] surfaces, adsorption energies of −1.90 and −2.55 eV were found, respectively. The second H2 molecule adsorption was found to be much stronger than the first H2 molecule adsorbed onto the Zr–TiO2 and Zr‒[TiO2+Vo] surfaces by 32.9% and 75.9%, respectively. Either the Zr–TiO2 or Zr‒[TiO2+Vo] surface is suggested as hydrogen–storage material and the Zr–TiO2 can be proposed as an electrical resistance‒based hydrogen sensor.