The effect of light on the reactivity of nanocrystalline metal oxides coated with quantum dots

    The project aims to create nanocomposites based on nanocrystalline oxide semiconductor SnO₂, In₂O₃, ZnO, sensitized nanocrystals (quantum dots) CdSe and study their interactions with the gas phase under irradiation with light. The problem of selectivity of heterogeneous reactions is key to creating chemical sensors and catalysts based on semiconductor materials. Solid - gas reactions on the surface of metal oxides occur with chemisorbed oxygen and have an activation character . The broad spectrum of active centers on the surface of semiconductor material by heating leads to the formation of products , the active surface passivation . Activation reactions light gives more control reactivity of materials. First to increase the sensitivity of the semiconductor matrix to visible light sensitizers used are embedded in the pores of the oxide semiconductor .

    Role sensitizers visible range of light - CdSe quantum dots 2-6 nm in diameter - is to shift the range of the optical sensitivity of semiconductor oxides toward longer wavelengths , which makes it possible to use radiation diodes visible spectrum with low power . Studies have demonstrated high sensitivity to irradiation of sensitized materials in the visible light range at the ambient temperature. During the project nanocrystalline oxides SnO₂, In₂O₃, ZnO, prepared in the form of powders with controlled crystallite size of 3-20 nm. The production technology of sensitizers - colloidal CdSe quantum dots controlled size stabilized by amphiphilic organic compounds , providing immobilization on the surface of semiconductor oxides. Various methods of immobilization of quantum dots on the surface of the semiconductor dies.

    The most effective sensitization ZnO is achieved by using water-soluble quantum dots CdSe. This immobilization procedure avoids contamination of the surface oxide organic molecules. Composition nanocomposite was determined by X-ray fluorescence analysis and ICP-MS. The microstructure of the materials was studied by scanning and transmission electron microscopy of high resolution.

    First investigated the photoconductivity and sensory properties of nanocrystalline ZnO, sensitized colloidal quantum dots CdSe, at room temperature under illumination in the visible range of the spectrum. Sensor measurements were carried out depending on the concentration of oxygen in the atmosphere and NO2 .

KEYWORDS

    Metal oxides, nanocrystalline semiconductors, sensitizers, quantum dots CdSe, light, solid - gas reactions, electrical, sensors, catalysts