Silver- and/or Nitrogen-Doped Titanium Dioxide Nanoparticles for Photocatalysis [thesis]

Zhiyuan Liu
TiO2 powders with varying Ag (3.125-12.500 mol% metal basis; single cation doping and codoping) and N (0.2-0.6 mL into 20 mL precursor solution; single anion doping and codoping) were fabricated by modified sol-gel method, followed by drying at room temperature for 12 h and then calcinated at 450°C for 5 h. The mineralogical, chemical, nanostructural, electronic and photocatalytic properties under both UV and visible irradiation of the thin films were determined. Anatase was the only phase in
more » ... sentially all the samples. XRD and XPS data revealed that, in Ag-doped TiO2 samples, Ag+ ions were likely to occupy one and both of two interstices at low-level and high-level doping, respectively. N3- ions were likely to substitute lattice O2- in N-doped TiO2 samples. However, Ag/N-doped TiO2 samples exhibited the coexistence of interstitial Ag+ and substitutional/interstitial N3- doping. XPS data indicated that both Ag doping, N doping, Ag/N codoping facilitated the formation of oxygen vacancies V_O^(••), while Ag doping and N doping could facilitate the formation of Ti3+. Further, XPS indicated the presence of Ag0 at high-doping levels, leading to the presence of Ag0/TiO2 heterojunction and the generation of Ag0/TiO2 heterojunction can be enhanced by the incorporation of N doping, which was confirmed by TEM images. SEM showed that the Ag doping was likely to suppress the agglomeration at high doping level while N doping and Ag/N codoping were likely to enhance the agglomeration. TEM suggested that N doping and Ag/N codoping caused expansion on TiO2 grains associated with the decreased surface area. Although Ag doping slightly affected grain size, the surface area of Ag-doped TiO2 samples increased and decreased with the increased doping level owing to the reduced porosity and densified agglomerates. PL spectra showed that both Ag and N doping could facilitate the photoexcitation. The photocatalytic performance test indicated that Ag doping generally enhanced the photocatalysis while only low-level nitrogen doping enhanc [...]
doi:10.26190/unsworks/21774 fatcat:qyjxnoe75zfp5eartlkknuyqim