Multiphase TiO₂nanostructures: a review of efficient synthesis, growth mechanism, probing capabilities, and applications in bio-safety and health

Abstract

This review article provides an exhaustive overview of efficient synthesis, growth mechanism and research activities of multiphase TiO2 nanostructures to provide their structural, morphological, optical and biological properties co-relations.

Insights into Theranostic Properties of Titanium Dioxide for Nanomedicine

“…When approaching nanoscale dimensions of bulk TiO 2 , quantum confinement occurs over superfine pieces and introduces new physical, mechanical, optical, and electronic properties [1,2]. Compared to conventional bulk materials, TiO 2 nanostructures (NSs), developed in different morphologies (i.e., sphere, tube, cylinder, fiber, sheet, whisker, wire, and rod) through feasible and reproducible fabrication strategies, have been employed in a wide range of leading-edge biomedical applications [2][3][4][5][6]. These efforts, for example, have resulted in enhancing drug delivery systems through the fabrication of porous TiO 2 nanocarriers due to a huge surface-to-volume ratio, which can enlarge the therapeutic loading capacity [7][8][9].…”

A review on spectral converting nanomaterials as a photoanode layer in dye‐sensitized solar cells with implementation in energy storage devices

“…As the size of materials/grains approaches to nanoscale dimensions, its physical and chemical characteristics differ significantly from that of bulk materials . It is caused due to interactions between atoms, anions with deficiencies, cations with valence states, anisotropy, and high surface/volume ratio . Depending on the orientation of nanocrystals, nanomaterials or nanostructured materials are classified in three main subclasses, within the size range of 1 to 100 nm (Figure ).…”

“…Among commonly used oxide nanomaterials, TiO 2 is one of the most widely used, it is used for multidisciplinary applications because of its several advantages, such as the presence in different phases, morphology, low‐cost, non‐toxicity, high abundance in nature, and slower charge carrier recombination process . TiO 2 nanostructures are wide bandgap semiconductor (2.8‐3.3 eV) material whose properties have captivated enormous interest in emerging technology …”

Synthesis of Anatase TiO2 Nanocrystals with Defined Morphologies from Exfoliated Nanoribbons: Photocatalytic Performance and Application in Dye‐sensitized Solar Cell

“…In nature, TiO 2 exists in four main polymorphs: anatase (PDF#21‐1272, tetragonal, I 4 1 / amd , a = b =3.785 Å, c =9.514 Å, α = β = γ =90°), rutile (PDF#21‐1276, tetragonal, P 4 2 / mnm , a = b =4.593 Å, c =2.959 Å, α = β = γ =90°), brookite (PDF#29‐1360, orthorhombic, Pcab , a =5.456 Å, b =9.182 Å, c =5.143 Å, α = β = γ =90°), and TiO 2 ‐B (PDF#46‐1237, monoclinic, C 2/ m , a =12.208 Å, b =3.749 Å, c =6.535 Å, α = γ =90°, β =107.36°). The relative stability of the TiO 2 phases depends mainly on the temperature and particle size . Thermodynamic calculations based on calorimetric data that rutile is the only stable form in bulk TiO 2 , whereas the brookite and anatase are metastable phases and transform exothermally and irreversibly to the rutile phase when they are increased to high temperatures (∼600 °C) .…”

“…[9] Thermodynamic calculations based on calorimetric data that rutile is the only stable form in bulk TiO 2 , whereas the brookite and anatase are metastable phases and transform exothermally and irreversibly to the rutile phase when they are increased to high temperatures (∼ 600°C). [9][10][11] If the particle sizes of the TiO 2 phases are equal, anatase phase is the most stable phase of TiO 2 at sizes below 11 nm, brookite is the most stable between 11 and 35 nm, and rutile is the most stable at sizes higher than 35 nm. [10] Among of the four polymorphs of TiO 2 , the anatase is considered to be the most photoactive one for the degradation of organic molecules because of the lowest photogenerated charge carriers recombine rate and the strong interaction of the organic molecules with the anatase surfaces.…”