(403i) Understanding the Anatase Particle Crystallization Pathways Via Various Organic/Inorganic Modifiers

Modulating the crystal shape and size with desirable exposed/terminating reactive facets is significant for fundamental studies and various technological applications. Anatase titania is the most extensively investigated advanced functional material due to its multitude of applications in Dye Sensitized Solar Cells (DSSCs), Lithium-ion batteries (LIB), degradation of organic pollutants and semiconductors. Therefore, the demand of titania particles with varying morphologies for different applications creates the need for a rational design of a non-hazardous, economical, and facile synthetic protocol.

Here we present a novel, economically feasible and simplistic wet chemistry approach to synthesize titania crystals with high index facets with particle size control over 3 orders of magnitude (5 nm-3000 nm). The synthesis of titania particles was carried out using a hydrothermal method. The synthesized samples were analyzed using analytical tools using XRD, BET surface area measurement technique, SEM, TEM, AFM, SAXS, XPS and DLS.

Herein, unique structures were generated such as coral -shaped structure, which provides high surface area while faceted crystals formed serve as host for active metal sites. Further, we have also explored the crystallization pathways of anatase crystals, which revealed that different precursor phases such as nanosheets, partially ordered domain, rod-shaped microcrystalline, needle-shaped crystallite, among others that generate an array of bulk crystals. These uncontrolled pathways were intervened using modifiers (organic molecules and inorganic salts) to generate more desired faceted crystals.

Overall, we show the complex dynamics of crystal growth where non-classical mode is predominant followed by monomer addition towards the end resulting in smooth bulk crystals. A complete blueprint will be presented for rational design of titania crystals. Here, we controlled three aspects of particle physiology: (i) size, (ii) dimensionality, and (iii) morphology. Titania is a multifunctional material with substantial industrial applications and therefore a facile synthetic strategy to produce particles with varying morphology becomes essential.