Photoresponse of Pd0/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/TiO₂ film is in the form of oxide, while FSEM showed that the PdO/TiO₂ film is porous. The photoconductivity of the PdO/TiO₂ 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 350degC was higher than that in 550degC. 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.