Hybrid Cu_<i>x</i>O/TiO₂ Nanocomposites As Risk-Reduction Materials in Indoor Environments

Photocatalytic TiO₂ powders impart ultraviolet light-induced self-cleaning and antibacterial functions when coated on outdoor building materials. For indoor applications, however, TiO₂ must be modified for visible-light and dark sensitivity. Here we report that the grafting of nanometer-sized Cu_<i>x</i>O clusters onto TiO₂ generates an excellent risk-reduction material in indoor environments. X-ray absorption near-edge structure using synchrotron radiation and high-resolution transmission electron microscopic analyses revealed that Cu_<i>x</i>O clusters were composed of Cu^I and Cu^II valence states. The Cu^II species in the Cu_<i>x</i>O clusters endow TiO₂ with efficient visible-light photooxidation of volatile organic compounds, whereas the Cu^I species impart antimicrobial properties under dark conditions. By controlling the balance between Cu^I and Cu^II in Cu_<i>x</i>O, efficient decomposition and antipathogenic activity were achieved in the hybrid Cu_<i>x</i>O/TiO₂ nanocomposites