Photoresponse of PdO/TiO₂ film under visible light

PdO/TiO₂ nanocomposites were prepared by ployol method. TEM, XPS and FSEM were used to observe and measure the microstructure and chemical state of the PdO/TiO₂ film. In this process, Pd(acac)₂ was a Pd precursor , ethylene glycol was a reductant, and nano TiO₂ powder (Degussa P25) was a support, in which the nanopaticles of Pd were highly dispersed on the surface of TiO₂. The Pd/TiO₂ was deposited on the alumina substrate with a comb-like gold electrode, then it was calcined at various temperature in air. XPS shows the Pd on the Pd/TiO ₂ film is in the form of oxide, while FSEM showed that the PdO/TiO₂ film is porous. The photoconductivity of the PdO/TiO ₂ film is measured under visible light in room temperature in pure N₂ or N₂ doped with 1000 ppm O₂ respectively. The results show that, in pure N₂, the photoconductivity of the PdO/TiO₂ film is strongly influenced by the sintering temperature. The photoconductivity of the sample sintered at 350°C was higher than that in 550°C. The photoconductivity of the film is also influenced by trace O₂ in N₂. Under continuous light irradiation, the photoconductivity of the film is responded to the doping of O₂ in N₂, which could decrease the photoconductivity remarkably. By this phenomenon, it is suggested that a trace oxygen sensor can be developed, which can work in room temperature.