Titanium Oxide Microspheres with Tunable Size and Phase Composition

Abstract

Due to their unique physical and chemical properties, monodisperse titanium oxide microspheres can be used in dye-sensitized solar cells, as cosmetic pigments, and for other applications. However, the synthesis of microspheres with narrow size distribution, desired phase composition, and porosity is still a challenge. In this work, spherical titania particles with controllable size, crystallinity, and pore size were obtained by Ti(OnBu)4 hydrolysis in ethanol. The influence of NaOH addition on the particles’ size and morphology was investigated for the first time. Particle diameter can be tailored from 300 nm to 1.5 μm by changing water and NaOH concentrations. Particle size was analyzed by the statistical processing of scanning electron microscopy (SEM) images and differential centrifugal sedimentation (DCS) measurements. Optical properties of the microspheres were studied by diffuse reflectance UV-Vis spectroscopy. Thermal and hydrothermal treatment allowed transforming amorphous phase in as-prepared particles into nanocrystalline anatase and/or rutile. Transmission electron microscopy (TEM) study of the lamellae, cut out from spherical particles using focused ion beam (FIB), revealed that as-synthesized microspheres are non-hollow, homogeneous, and crystallize throughout the whole volume of the particle. The spherical particles possess photoprotective properties; the highest sun protection factor (SPF) was observed for amorphous microspheres.

Effect of chitosan on the electrokinetic, spectroscopic, and textural properties of TiO2 nanoparticles

“…The titanium dioxide nanoparticles (TiO 2 NP) were synthetized by the sol-gel method as previously reported by Poluboyarinov (2019). Briefly, 16 mL of sodium hydroxide (NaOH, Meyer, 0.015 M) were added to 15 mL of ethanol (C 2 H 6 O, Meyer, 99.5%).…”

A Path toward Inherently Asymmetric Micromotors

“…[ 10,11 ] Among the broad range of semiconducting photocatalytic materials, TiO 2 has emerged as one of the most widely used photocatalysts inside and outside of active matter, due to its low cost, high photoactivity, physical and chemical robustness, and low environmental toxicity. [ 12 ] Methods for synthesizing spherical TiO 2 particles ranging from the nano‐ to the microscale are abundant, [ 13,14 ] but for spherical particles on a solid substrate and illuminating from below, the shadow effect is usually not sufficient to induce active motion. [ 15 ] Chen et al were able to control the motion of isotropic microparticles by changing the position of the UV light source.…”

Ultraviolet shielding properties of cotton fabric supported by titanium-calcium hydroxyapatite solid solution particles

“…17,22 Titanium oxide (IV) is also known to be a UV absorber 23–32 and it is used in suntan lotion to protect skin 24 and in cosmetic applications. 25 The composite of zinc oxide (ZnO) and TiO 2 26–28 and the composite of silver (Ag) and TiO 2 29 are also used as UV absorbers. TiO 2 30 and the composite of TiO 2 and polyvinylsilsesquioxane 31 were supported on cotton fabric and the UV protecting blocking ability of the cotton was investigated.…”

“…20,21 It is reported that cerium-calcium hydroxyapatite (CeCaHap) also has this UV-absorption capability. 17,22 Titanium oxide (IV) is also known to be a UV absorber [23][24][25][26][27][28][29][30][31][32] and it is used in suntan lotion to protect skin 24 and in cosmetic applications. 25 The composite of zinc oxide (ZnO) and TiO 2 [26][27][28] and the composite of silver (Ag) and TiO 2 29 are also used as UV absorbers.…”