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.
In our work, we achieve the multi-component assembly of novel kinds of photofunctional hybrid materials with polyoxometalates (POMs, Na 9 EuW 10 O 36 ·32H 2 O (EuW 10 O 36 9 - denoted as EuW10)) and benzoate (4-aminobenzoate, 4-hydroxybenzoate, 4-mercaptobenzoate) modified mesoporous silica through imidazolium ionic liquid (IL, 1-methyl-3-(trimethoxysilylpropyl) compound as double functional linkage. Using Pluronic P123 surfactant as a template, benzoate functionalized SBA-15 mesoporous host is synthesized as result of the co-condensation of tetraethoxysilane (TEOS) and benzoate modified siloxane as precursor. We fabricate POM into the framework of functionalized SBA-15 mesoporous silica with IL. Here IL behaves as double linkage, which both interact with PMO with electrostatic force through ion exchange and form covalent bond to the functionalized SBA-15 mesoporous silica through its alkoxy group after cohydroxylysis and copolycondensation process. Tb 3+ is further introduced into the above hybrid system through coordination bond to carboxylate group of benzoate unit, which can be expected to modify luminescence color and to obtain close white luminescence. The physical characterizations prove these hybrid materials possess high surface area, uniform mesoporous structure, good crystallization and relatively excellent luminescence properties.
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