Study of concentration-dependent cobalt ion doping of TiO2 and TiO2−xNx at the nanoscale

Abstract

Experiments with a porous sol-gel generated TiO(2) nanocolloid and its corresponding oxynitride TiO(2-x)N(x) are carried out to evaluate those transformations which accompany additional doping with transition metals. In this study, doping with cobalt (Co(ii)) ions is evaluated using a combination of core level and VB-photoelectron and optical spectroscopy, complementing data obtained from Raman spectroscopy. Raman spectroscopy suggests that cobalt doping of porous sol-gel generated anatase TiO(2) and nitridated TiO(2-x)N(x) introduces a spinel-like structure into the TiO(2) and TiO(2-x)N(x) lattices. TEM and XPS data complemented by valence band-photoelectron spectra demonstrate that metallic cobalt clusters are not formed even at high doping levels. As evidenced by Raman spectroscopy, the creation of a spinel-like structure is commensurate with the room temperature conversion of the oxide and its oxynitride from the anatase to the rutile form. The onset of this kinetically driven process correlates with the formation of spinel sites within the TiO(2) and TiO(2-x)N(x) particles. Despite their visible light absorption, the photocatalytic activity of these cobalt seeded systems is diminished relative to the oxynitride TiO(2-x)N(x).

Dipole‐Induced Band‐Gap Reduction in an Inorganic Cage

“…Cages 3 and 4 are the largest transition-metal-containing POT cages to be reported to date and can be regarded as nano-sized molecular relatives of cobalt(II)-doped TiO 2 nanoparticles. [26][27][28] The molecular arrangements in 1 and 2 are similar to those reported for the …”

“…Cages 3 and 4 are the largest transition-metal-containing POT cages to be reported to date and can be regarded as nano-sized molecular relatives of cobalt(II)-doped TiO 2 nanoparticles. [26][27][28] The molecular arrangements in 1 and 2 are similar to those reported for the Co II chloride analogues, [19] and can be viewed as being composed of [Ti 4 (OEt) 15 The complexes contain combinations of m 2 -, m 3 -, m 4 -, and m 5 -O oxo ligands, and exclusively six-coordinate Ti IV in 1, 2, and 3, and five-and six-coordinate Ti IV in 4. For comparison the three common polymorphs of TiO 2 (rutile, anatase, and brookite) have exclusively six-coordinate Ti and m 3 -O centers.…”

Synthesis, surface morphology, and photoluminescence properties of anatase iron-doped titanium dioxide nano-crystalline films

“…21,22 However, it is difficult to obtain nanostructured TiO 2 films with a uniformly dispersed Fe replacement due to the fast hydrolysis and condensation rates via the traditional sol-gel/ hydrolysis method, which results in lattice strain, expansion, and Ti deficiency. 23,24 In the present work, a facile non-hydrolytic sol-gel procedure was used to synthesize the homogeneous Fe-doped TiO 2 films with a variety of different Fe compositions (from 0 to 4%).…”

Preparation and Characterization of Ni-Doped Materials for Photocurrent and Photocatalytic Applications

“…As p-GaP undergoes photocorrosion; there has been a continuous quest for stable oxide-based p-type semiconducting materials for PEC applications [8]. Given its superior corrosion resistance and most promising flat band potentials suitable for artificial photosynthesis reactions, more focus was made on TiO 2 to convert it from n-type conducting to p-type, and to reduce its bandgap energy and recombination of its photogenerated electron-hole pairs [13–20]. The p-type conducting behavior was occasionally observed for TiO 2 after doping with certain metal ions such as Fe 3+ , Co 3+ , Ni 2+ , Cu 1+ [8, 13–20].…”

“…Given its superior corrosion resistance and most promising flat band potentials suitable for artificial photosynthesis reactions, more focus was made on TiO 2 to convert it from n-type conducting to p-type, and to reduce its bandgap energy and recombination of its photogenerated electron-hole pairs [13–20]. The p-type conducting behavior was occasionally observed for TiO 2 after doping with certain metal ions such as Fe 3+ , Co 3+ , Ni 2+ , Cu 1+ [8, 13–20]. The change of semiconducting behavior has been attributed to the heterounions formed between n-type TiO 2 and p-type metal oxide dopant [18].…”