Non-solvolytic synthesis of aqueous soluble TiO2 nanoparticles and real-time dynamic measurements of the nanoparticle formation

Abstract

Highly aqueously dispersible (soluble) TiO2 nanoparticles are usually synthesized by a solution-based sol–gel (solvolysis/condensation) process, and no direct precipitation of titania has been reported. This paper proposes a new approach to synthesize stable TiO2 nanoparticles by a non-solvolytic method - direct liquid phase precipitation at room temperature. Ligand-capped TiO2 nanoparticles are more readily solubilized compared to uncapped TiO2 nanoparticles, and these capped materials show distinct optical absorbance/emission behaviors. The influence of ligands, way of reactant feeding, and post-treatment on the shape, size, crystalline structure, and surface chemistry of the TiO2 nanoparticles has been thoroughly investigated by the combined use of X-ray diffraction, transmission electron microscopy, UV-visible (UV–vis) spectroscopy, and photoluminescence (PL). It is found that all above variables have significant effects on the size, shape, and dispersivity of the final TiO2 nanoparticles. For the first time, real-time UV–vis spectroscopy and PL are used to dynamically detect the formation and growth of TiO2 nanoparticles in solution. These real-time measurements show that the precipitation process begins to nucleate after an initial inhibition period of about 1 h, thereafter a particle growth occurs and reaches the maximum point after 2 h. The synthesis reaction is essentially completed after 4 h.

The Effect of Titanium Dioxide Nanoparticles on Salivary Alkaline Phosphatase Activity

“…This peak was around 240 nm. This result is in agreeement with that of Chen et al [20], which indicate the absorbance intensity of GalA-TiO2 NPs dispersion in the UV region at <300 nm. Figure 4, it is concluded that 100 µl of saliva is the best volume for measuring the ALP activity according to the conditions of experiments.…”

Hydrolysis of organometallic and metal–amide precursors: synthesis routes to oxo-bridged heterometallic complexes, metal-oxo clusters and metal oxide nanoparticles

“…Whilst the metal oxide phase precipitates as small NPs the by-product NaCl remains dissolved in the alcoholic solution. The process can be used for a variety of metal oxide products such as Cu2O, WO3 or even ternary phases such as CoFe2O3, 199,200 with additives (e.g. alkylamines and oleic acid) enabling improved monodispersity of the NPs.…”

Non-aqueous sol–gel synthesis through a low-temperature solvothermal process of anatase showing visible-light photocatalytic activity

“…Amongst the reported processes, the most common are the hydrothermal and solvothermal methods, in which the precursor is precipitated in water, organic solvents or ionic liquids, and the precipitate is crystallised by a thermal treatment. 23,24 The solvothermal route is one of the most extensively applied methods for the synthesis of NPs. Buonsanti et al developed a novel method to prepare unique branched-shaped nanocrystals of TiO 2 NPs, by mixing titanium carboxylate complexes and mixtures of oleic acid and oleyl amine at 240-320 °C.…”