Molecular adsorption behavior of O₂ molecules on Ni²⁺ doped TiO₂ (001) crystal plane

The adsorption of Ni²⁺ doped TiO₂ (001) crystal plane for different gas molecules is studied by combining theory with experiment. The results show that O₂ molecules are adsorbed on crystal plane in the form of chemical bond. XPS results prove that the doping of Ni²⁺ increases the chemisorbed oxygen ability of crystal plane. The adsorption of O₂ molecules leads to the increase of the crystal plane conductivity, which is confirmed by the simulation results of the increase of Fermi level DOS and the electrochemical impedance spectroscopy (EIS) experiment. H₂O and N₂ molecules are adsorbed by crystal plane in the form of hydrogen bond and physical adsorption, respectively, and their contributions to the crystal plane conductivity increase and decrease respectively, which is also confirmed by EIS under different atmospheres. Interestingly, small-angle XRD proves that the sample exists interlayer clearance, and the adsorption of gas molecules in the crystal surface gap further improves the storage capacity of TiO₂ materials for gas molecules. The results of this study are of great significance for improving the oxygen carrying capacity and catalytic gas sensitive performance of TiO₂ materials.