(bandgap of 3.2 eV) have the fundamental absorption edge in the UV range. The most plausible explanation is that a significant density of intra-gap states is formed in TiO2 after heating in the presence of NiOx. Indeed, X-ray photoelectron spectroscopy (XPS) of NiOx-TiO2 revealed a significant amount of Ti 3+ and of Ti 4+ species with the binding energy shifted due to structural disorder-induced effects (see Fig. in the Supporting Information). The Ti 3+ 3d states are known to lie energetically below the conduction band edge of TiO2 . Such occupied intragap states do not shift completely the fundamental absorption edge, but make themselves apparent as an absorption shoulder (Urbach tail) below the fundamental absorption edge (see Fig. and Fig. in the Supporting Information), and provide thus a plausible explanation for the significant sub-bandgap photocurrent response of the NiOx-TiO2 photocathode.