The collapse of nanotube structure is due to the dehydration of interlayered OH groups and crystallinity transition from orthorhombic system to anatase under calcination. In this work, the Zr/N co-doped NTA can still keep the nanotube structures with 400°C calcination. Figure 2c,d presents the 0.6% Zr/N-TiO2 samples after thermal treatment at 500°C and 600°C. The nanotubular morphology of NTA precursor was changed to nanoparticles

with high temperature calcination. Compared with the sample of 0.6% Zr/N-TiO2(600) calcinated at 600°C, sample of 0.6% Zr/N-TiO2(500) shows smaller pure anatase particles with size of ca. 10 nm and partially Selleckchem VX 809 retained nanotubular structures. As we know, a smaller crystallite size, high surface area, and greater thermal stability Blasticidin S research buy are highly desirable properties for photocatalysts. Anatase type TiO2 nanoparticles with small particle sizes (typically less than 10 nm) had exhibited enhanced photocatalytic

activity because of the large specific surface area and quantum size effect [19, 20]. In this work, better photocatalytic activity of 0.6% Zr/N-TiO2 (500) sample was highly expected due to its pure anatase crystallinity and smaller crystallite size. Figure 2 TEM images of NTA precursor (a) and 0.6%Zr/N-TiO 2 prepared at 400°C (b), 500°C (c), and 600°C (d). The surface areas of different doped samples measured by BET are shown in Tables 1 and 2. The BET results in Table 1 show that zirconium doping of x%-Zr-N-TiO2-500 samples at the same calcination temperature exhibit an Selleck Combretastatin A4 increase of specific surface area with increasing Zr content. This trend is due to the gradual

decrease of crystallinity and particle sizes of anatase TiO2 as demonstrated by XRD results in Figure 1a. The surface area data in Table 2 of 0.6%-Zr-N-TiO2 samples calcined at different temperatures show a decreasing trend with the increase of calcination temperature. The XRD results Sclareol in Figure 1b and TEM analysis in Figure 2 show that with increasing calcination temperature, the average crystallite size increases, in contrast with the BET surface areas that decrease. Table 1 BET surface areas of the x%-Zr-N-TiO 2 -500 samples with different Zr doping concentration calcined at 500°C Samples ( x %-Zr-N-TiO2-500) Surface areas (m2g−1) 0.1 122.31 0.3 142.96 0.6 143.04 1.0 166.25 5.0 218.18 10.0 240.18 Table 2 BET surface areas of the 0.6%-Zr-N-TiO 2 samples calcined at different temperatures Calcination temperature (°C) Surface area (m2g−1) 400 320.54 500 143.04 600 112.01 Surface compositions of Zr/N co-doped TiO2 samples were investigated by XPS. Figure 3a,b shows the high resolution XPS spectra of Ti 2p and O 1s for sample of 0.6% Zr/N-TiO2(500). The binding energies of Ti 2p3/2 and Ti 2p1/2 components of 0.6% Zr/N-TiO2(500) are located at 458.9 and 464.8 eV, corresponding to the existence of Ti4+ state [11–13].