33 research outputs found
Antiviral Effect of Visible Light-Sensitive CuxO/TiO2 Photocatalyst
Photocatalysis is an effective technology for preventing the spread of pandemic-scale viruses. This review paper presents an overview of the recent progress in the development of an efficient visible light-sensitive photocatalyst, i.e., a copper oxide nanoclusters grafted titanium dioxide (CuxO/TiO2). The antiviral CuxO/TiO2 photocatalyst is functionalised by a different mechanism in addition to the photocatalytic oxidation process. The CuxO nanocluster consists of the valence states of Cu(I) and Cu(II); herein, the Cu(I) species denaturalizes the protein of the virus, thereby resulting in significant antiviral properties even under dark conditions. Moreover, the Cu(II) species in the CuxO nanocluster serves as an electron acceptor through photo-induced interfacial charge transfer, which leads to the formation of an anti-virus Cu(I) species and holes with strong oxidation power in the valence band of TiO2 under visible-light irradiation. The antiviral function of the CuxO/TiO2 photocatalyst is maintained under indoor conditions, where light illumination is enabled during the day but not during the night; this is because the remaining active Cu(I) species works under dark conditions. The CuxO/TiO2 photocatalyst can thus be used to reduce the risk of virus infection by acting as an antiviral coating material
Visible-Light-Sensitive Photocatalysts: Nanocluster-Grafted Titanium Dioxide for Indoor Environmental Remediation
Photocatalytic
degradation of organic compounds requires photoexcited
holes with strong oxidative power in the valence band (VB) of semiconductors.
Although numerous types of doped semiconductors, such as nitrogen-doped
TiO<sub>2</sub>, have been studied as visible-light-sensitive photocatalysts,
the quantum yields of these
materials were very low because of the limited oxidation power of
holes in the nitrogen level above the VB. Recently, we developed visible-light-sensitive
Cu(II) and Fe(III) nanocluster-grafted TiO<sub>2</sub> using a facile
impregnation method and demonstrated that visible-light absorption
occurs at the interface between the nanoclusters and TiO<sub>2</sub>, as electrons in the VB of TiO<sub>2</sub> are excited to the nanoclusters
under visible-light irradiation. In addition, photogenerated holes
in the VB of TiO<sub>2</sub> efficiently oxidize organic contaminants,
and the excited electrons that accumulate in nanoclusters facilitate
the multielectron reduction of oxygen. Notably, Cu(II) and Fe(III)
nanocluster-grafted TiO<sub>2</sub> photocatalyst has the highest
quantum yield among reported photocatalysts and has antiviral, self-cleaning,
and air purification properties under illumination by indoor light
fixtures equipped with white fluorescent bulbs or white light-emitting
diodes