title: Hydrothermal-hydrolysis synthesis and photocatalytic properties of nano-TiO2 with an adjustable crystalline structure.
abstract: Tri-phase (anatase, rutile, and brookite), bi-phase (anatase and rutile), and mono-phase (rutile) TiO(2) nanomaterials with different morphologies were successively synthesized using a hydrothermal-hydrolysis method and adjusting the Ti(4+)/Ti(3+) molar ratio in a precursor solution. The properties of the fabricated nanomaterials were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photocatalytic reaction, and other techniques. It has been shown that TiO(2) nanorods can be obtained by increasing the Ti(4+)/Ti(3+) molar ratio in a precursor solution from 1:0 to 0.3:0.7. TiO(2) nanoparticles are formed if the Ti(3+) fraction in the solution is further increased. The selective synthesis of TiO(2) nanomaterials is explained by a decrease in the reaction rate and by changes in acidity with increasing Ti(3+) content. The tri-phase nanorods and bi-phase nanoparticles synthesized with Ti(4+)/Ti(3+) molar ratios from 1:0 to 0.8:0.2 and 0.2:0.8 to 0:1, respectively, have a higher degradation ability with respect to methylene blue aqueous solutions under UV irradiation at ambient temperature compared to purely rutile TiO(2) nanorods synthesized with Ti(4+)/Ti(3+) molar ratios from 0.7:0.3 to 0.3:0.7. The high photocatalytic activity of the multi-phase TiO(2) samples is primarily attributed to their larger band gap and suppressed recombination of photo-generated electron-hole pairs.
authors.affiliation: School of Chemistry and Environment, Key Lab of Electrochemical Technology on Energy Storage and Power Generation in Guangdong Universities, South China Normal University, Guangzhou 510006, China.
authors.forename: Jinghuan
authors.initials: J
authors.lastname: Zhang
authors.forename: Xin
authors.initials: X
authors.lastname: Xiao
authors.forename: Junmin
authors.initials: J
authors.lastname: Nan
mesh_terms: D002384:Catalysis; D003460:Crystallization / Q000379:methods*; D006868:Hydrolysis; D049329:Nanostructures; D055668:Photochemical Processes; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: C009495:titanium dioxide; D014025:Titanium