Titania (titanium dioxide, TiO2) has attracted tremendous attentions as a semiconductor photocatalyst in the past decades due to its superior features including chemical stability, low cost, high reusability and excellent degradation efficiency of organic pollutants.1-2 However, some issues have hampered its large scale application. For example, the wide-band-gap (Eg = 3.2 eV) indicates that it can only be excited by ultraviolet light; the low electron transfer rate to oxygen and high recombination rate of photogenerated electrons and holes pairs greatly limit its catalytic efficiencies.