Fabrication And Application Of Functional Nanomaterials Based On Polyoxometalate

Polyoxometalates (POMs) are a well-known class of discrete early transition metal-oxide nanoclusters Their versatile nature, in terms of structure, size, redox chemistry, photochemistry and charge distribution, could lead to a large range of interests in fundamental and applied science. On the application front, POMs have proven to be invaluable including in catalysis (especially for green chemistry), medicine (antitumor, antiviral, antimicrobacterial activities, and insulin mimetic), analytical chemistry, and become attractive inorganic components for fabrication of advanced materials and devices with unique magnetic, optical and electrical properties. A major challenge facing those engaged in POM application is to devise general methods for constructing functional nanoscale architectures from these versatile building blocks.In this thesis, a thin film with reversible photoswitchable fluorescence was prepared by combing inorganic quantum dots, CdSe@CdS core-shell nanoparicles, and photochromic POMs through layer-by-layer assembly technique. The prepared thin films exhibit strong fluorescence because of the luminescent core-shell CdSe@CdS nanoparticles. Upon irradiation with UV light, the fluorescence of the film was quenched. The quenching of the thin film is attributed to the occurrence of the fluorescence resonance energy transfer (FRET) between luminescent CdSe@CdS NPs and POMs in reductive state. The fluorescence of thin film can be recovered by irradiated under room light for several hours. Such thin film with reversible photoswitchable fluorescence.can find applications in photonic storage and cell labling.