Synthesis of Anatase TiO₂ Nanocrystals with Exposed {001} Facets

Abstract

This paper reports a facile synthesis of anatase TiO(2) nanocrystals with exposed, chemically active {001} facets. The nanocrystals were prepared by digesting electrospun nanofibers consisting of amorphous TiO(2) and poly(vinyl pyrrolidone) with an aqueous acetic acid solution (pH = 1.6), followed by hydrothermal treatment at 150 degrees C for 20 h. The as-obtained nanocrystals exhibited a truncated tetragonal bipyramidal shape with 9.6% of the surface being enclosed by {001} facets. The use of electrospinning is critical to the success of this synthesis as it allows for the generation of very small particles of amorphous TiO(2) to facilitate hydrothermal crystallization, an Ostwald ripening process. The morphology of the nanocrystals had a strong dependence on the pH value of the solution used for hydrothermal treatment. Low pH values tended to eliminate the {001} facets by forming sharp corners while high pH values favored the formation of a rodlike morphology through an oriented attachment mechanism. When acetic acid was replaced by inorganic acids, the TiO(2) nanocrystals further aggregated into larger structures with various morphologies.

Tuning TiO2nanoparticle morphology in graphene–TiO2hybrids by graphene surface modification

“…The HR-TEM evidences a line spacing of 0.34 nm in the exposed trapezoidal facets, identifying them as anatase {101} surfaces. 20 The particles are thus predominantly bound to GNP as shown in the schematic in Fig. 9c.…”

“…17 This morphology can be changed by synthesizing anatase NPs in the presence of specific shape controllers. 12,[18][19][20] A first breakthrough was achieved by Lu et al, 21,22 who synthesized TiO 2 NPs with a very high percentage of exposed {001} facets using hydrofluoric acid; such particles showed excellent photocatalytic activity. Most of the shape controllers used in TiO 2 synthesis have amino and carboxylic groups in their structure, since these functionalities are known to interact with TiO 2 facets.…”

Specific Facets-Dominated Anatase TiO2: Fluorine-Mediated Synthesis and Photoactivity

“…The nanocrystals were prepared by digesting electrospun nanofibers consisting of amorphous TiO 2 and poly(vinylpyrrolidone) with an aqueous acetic acid solution (pH = 1.6), followed by hydrothermal treatment at 150 °C for 20 h. The as-obtained nanocrystals exhibited a truncated tetragonal bipyramidal shape with 9.6% of the surface being enclosed by {001} facets [69]. The use of electrospinning was critical to the success of this synthesis as it allows the generation of very small particles of amorphous TiO 2 to facilitate hydrothermal crystallization, an Ostwald ripening process.…”

Effect of heating on the structural and optical properties of TiO2 nanoparticles: antibacterial activity

“…The biological, chemical and physical properties are prominently influenced by the crystal phase, geometry and particle size (Yang et al 2008(Yang et al , 2009Han et al 2009). Because of its heat stability, low cost and biocompatibility, they are widely used as cosmetic and skin care especially in sun block cream, pigment, sensors and photo catalyst (Dai et al 2009;Joo et al 2005;Li and Wang 2003;Arami et al 2007;Sun et al 2011).…”