Figure 4

(a) The core level photoelectron spectra of Ti(2p), (b) valance band regions, (c) Tauc plot, and (d) schematic of XPS alignment with band gap obtained from Tauc plot of anatase and rutile TiO₂. ΔE_V and ΔE_C are the valance band offsets and conduction band offsets, respectively and ΔE_CL core level offset between the Ti(2p_3/2) core levels. E^VBM and E^CBM are the positions of the valance and conduction band, respectively and Eg is band gap obtained from Tauc plot.