Interface modification of titanium dioxide nanoparticles by titanium-substituted polyoxometalate doping for improvement of photoconductivity and gas sensing applications

TiO 2 nanoparticles are commonly used as versatile precursors to make functional nanocomposite materials. However, the surface defects at grain boundaries of TiO 2 nanoparticles significantly affect the photoelectric properties of TiO 2 nanomaterials . In this work, we firstly prepared nanocomposites of TiO 2 and polyoxometalates (POMs) in which different POMs, including titanium-substituted POMs K 5 [PW 11 TiO 40 ] and K 7 [PW 10 Ti 2 O 40 ], are incorporated with TiO 2 nanoparticles so as to make an interface modification on grain boundaries of TiO 2 nanoparticles. Then the photoconductivities of the TiO 2 /POM nanocomposites were investigated through measurement of photocurrent responses, current-voltage curves, Mott-Schottky plots and surface photocurrent spectra. Compared with pure TiO 2 nanoparticles, TiO 2 /POM nanocomposites exhibit superior photoelectric properties, benefitting from the interface modification from different POMs. The gas sensing performance for acetone was also explored by use of the as-prepared photoconductive devices, and TiO 2 /PW 11 Ti exhibited a high gas sensing performance.