Indoor surface contamination by microbes is a major public health concern. A damp environment is one potential sources
for microbe proliferation. Smart photocatalytic coatings on building surfaces
using semiconductors like titania (TiO<sub>2</sub>) can effectively curb this
growing threat.<b> </b>Metal-doped
titania in anatase phase has been proved as a promising candidate for energy
and environmental applications. In this present work, the antimicrobial
efficacy of copper (Cu) doped TiO<sub>2 </sub>(Cu-TiO<sub>2</sub>) was
evaluated against <i>Escherichia coli</i> (Gram-negative) and <i>Staphylococcus
aureus</i> (Gram-positive) under visible light irradiation. Doping of a minute
fraction of Cu (0.5 mol %) in TiO<sub>2 </sub>was carried out <i>via</i> sol-gel technique. Cu-TiO<sub>2</sub>
further calcined at various temperatures
(in the range of 500 °C – 700 °C) to evaluate the thermal stability of TiO<sub>2</sub>
anatase phase. The physico-chemical properties of the samples were
characterised through X-ray diffraction (XRD), Raman spectroscopy, X-ray
photo-electron spectroscopy (XPS) and UV-visible spectroscopy techniques. XRD
results revealed that the anatase phase of TiO<sub>2</sub> was maintained well,
up to 650 °C, by the Cu dopant. UV-DRS results suggested that the visible light
absorption property of Cu-TiO<sub>2 </sub>was enhanced and the band gap is
reduced to 2.8 eV. Density functional theory (DFT) studies emphasises the
introduction of Cu<sup>+</sup> and Cu<sup>2+</sup> ions by replacing Ti<sup>4+</sup>
ions in the TiO<sub>2</sub> lattice, creating oxygen vacancies. These further
promoted the photocatalytic efficiency. A significantly high bacterial
inactivation (99.9%) was attained in 30 mins of visible light irradiation by
Cu-TiO<sub>2</sub>.
Singlet oxygen generation properties of an inclusion complex of cyclic free-base porphyrin dimer and fullerene C60