3 and 532.0 eV. The strong peak of 530.3 eV is ascribed to lattice oxygen in Ti-O bonds, and the small peak #learn more randurls[1|1|,|CHEM1|]# around 532.0 eV is ascribed to weakly

physical adsorbed oxygen species such as O– and OH group on the surface [11–13]. The N 1s and Zr 3d spectra for samples of 0.6% Zr/N-TiO2(500) can be observed in Figure 3c,d. The N 1s binding energy peaks are broad, extending from 396 to 403 eV. The center of the N1s peak locates at ca. 400.1 eV. In general, the assignment of the N 1s peak in the XPS spectra is under debate in the literature according to different preparation methods and conditions. We had attributed the N 1s peak at 400 eV to the interstitial N in the form of Ti-O-N in our previous reports [11–13]. Zr 3d peaks at 182.2 and 184.5 eV corresponding to the Zr 3d5/2 and Zr 3d3/2, respectively, are assigned to the Zr4+ state of zirconium [16]. The above XPS results indicate that both nitrogen and zirconium are doped into the TiO2 samples after calcination at 500°C. Figure 3 High-resolution XPS spectra of Ti 2p (a), O 1 s AZD5363 (b), N 1 s (c), and Zr 3d (d) for sample of 0.6% Zr/N-TiO

2 (500). Optical absorption properties of precursors (P25 and NTA), Zr doped and Zr/N co-doped P25 and NTA were studied by the diffuse reflectance in visible light region. Figure 4 shows the UV–vis DRS of prepared samples in the range of 400 to 700 nm. The undoped sample of P25 and NTA shows no visible light absorption. Zirconium mono-doped NTA sample also presents no obviously visible light absorption. It

indicates that zirconium mono-doping may not lead Sirolimus manufacturer to the bandgap narrowing of TiO2 with NTA as precursor. Theoretical studies had proved that Zr mono-doping did not change the bandgap of TiO2 and eventually did not exhibit better absorption ability in visible light region [8]. However, the spectra of Zr/N co-doped NTA shows a significantly broader absorption shifted to the visible region. While the absorption edge of Zr/N co-doped P25 sample only gets a slight shift to the visible region. The significant visible light absorption of Zr/N NTA indicates that the NTA is a better candidate than P25 as a precursor for N doping. We had reported the effect of annealing temperature on the morphology, structure, and photocatalytic behavior of NTA precursor [11]. The NTA experienced the process of dehydration and crystallinity transition during calcination, which is clearly beneficial for the N doping into the lattice of TiO2. Moreover, single-electron-trapped oxygen vacancies (SETOV) were generated in the dehydration process [11]. In a recent study of visible light absorption and photocatalytic activity of N doped NTA, we demonstrated that the absorption shift to the visible light region of N-NTA samples is ascribed to the formation of single-electron-trapped oxygen vacancies (SETOV) in TiO2 matrix and nitrogen doping [15].