Abstract

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 CuxO 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 CuxO clusters were composed of CuI and CuII valence states. The CuII species in the CuxO clusters endow TiO2 with efficient visible-light photooxidation of volatile organic compounds, whereas the CuI species impart antimicrobial properties under dark conditions. By controlling the balance between CuI and CuII in CuxO, efficient decomposition and antipathogenic activity were achieved in the hybrid CuxO/TiO2 nanocomposites.