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  • Impact of the absolute rutile fraction on TiO2 visible-light absorption and visible-light-promoted photocatalytic activity
    Tobaldi, David Maria ...
    Titanium dioxide is by far the most used semiconductor material for photocatalytic applications. Still, it is transparent to visible-light. Recently, it has been proved that a type-II band alignment ... for the rutile -anatase mixture would improve visible-light absorption. In this research paper we thoroughly characterised the real crystalline and amorphous phases of synthesised titanias - thermally treated at different temperatures to get distinct ratios of anatase-rutile-amorphous fraction - as well as that of three commercially available photocatalytic nano-TiO2. Optical spectroscopy showed that even a small fraction of rutile (2 wt%) is able to shift to lower energies the apparent optical band gap of an anatase-rutile mixed phase. But is this enough to attain a real photocatalytic activity promoted by merely visible-light? We tried to give an answer to that question. Photocatalytic activity was assessed in the liquid- and gas-solid phase (employing rhodamine B and 4-chlorophenol, and isopropanol, respectively, as the organic substances to degrade) using a light source irradiating exclusively in the visible-range. Photocatalytic activity results in the liquid-solid phase showed that a high surface hydroxylation led to specimen with superior visible light-promoted catalytic activity - i.e. dye and ligand-to-metal charge transfer complexes sensitisation effects, not photocatalysis sensu-strictu. On the other hand, the gas-solid phase results showed that a higher amount of the absolute rutile fraction (around 10 wt%), together with less recombination of the charge carriers, were more effective for both visible-light absorption and a "real" visible-light promoted photocatalytic oxidation of isopropanol.
    Vir: Journal of photochemistry and photobiology. A, Chemistry. - ISSN 1010-6030 (Vol. 382, Sept. 2019, str. 1-15)
    Vrsta gradiva - članek, sestavni del
    Leto - 2019
    Jezik - angleški
    COBISS.SI-ID - 2464615

    Povezava(-e):

    https://www.sciencedirect.com/science/article/abs/pii/S1010603019303533?via%3Dihub
    DOI

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