Hydrogen sensing characteristics and mechanism of nanosize TiO2 dope with metallic ions

Nanosize TiO2 doped with metallic ions including Ag+, Sb2+, Ni2+ , Co2+, and Ce3+ powders were prepared by sol–gel method. X-ray diffraction was used to confirm the phase composition of the powders. Hydrogen sensing characteristics of these samples were investigated. The first-principles approach of density functional theory (DFT) is used to study the density of state (DOS) of TiO2-doping metallic ions. The results show that hydrogen sensing property of the TiO2 was remarkably enhanced by adding Ag+, its sensitivity value is 3.6 to 200 ppm hydrogen at 360 °C. The DOS of Sb2+, Ni2+, Co2+ and Ce3+ doped-TiO2 has not been changed obviously after adsorbing H atom, while the DOS of Ag+-doped TiO2 has changed distinctly. The variety of the electronic structure of Ag+-doped TiO2 cause the change of the conductance of the sensor, so the hydrogen sensing properties of TiO2 can be enhanced by doping Ag+ ion.