Bachelor_ARL_Crystal growth of TiO2 with molten salt synthesis

Advanced Research Lab-Thesis / Bachelor Thesis

Figure 1: Main shapes and applications for TiO2 polymorphs. [5]
Figure 1: Main shapes and applications for TiO2 polymorphs. [5]

Facet engineering and crystal growth of TiO2 with molten salt synthesis

This research work is strictly related to a scientific cooperation with the company Merck KGaA. Students are invited to apply either for the bachelor thesis or for the advanced research lab

Description:

Being able to control the phase and the morphology of materials is a demanding and sought ability. Molten salt synthesis (MSS) is one of the methods of preparing ceramics powders, which implies the use of a large amount of salt heated above its melting point and therefore acting as a solvent.1 It is a common method to grow single crystals from solution, can be easily scaled up for the fabrication of large quantities of materials and allows controlling particle size, particle shape and agglomeration state.2–4

TiO2 is one of the most investigated binary metal oxides, due to its wide range of application, from the most conventional ones like pigment, cosmetic, paint to those were functional properties of titania become of great importance like photoelectrochemical cells, dye-sensitized solar cells, photocatalysis, catalysis, photovoltaic cells, sensors and as electrode material for Li-ion batteries. Most of these applications are based on the interaction between molecules and ions with the TiO2 crystal surfaces.5 Since the various facets of TiO2 interact in a different way with ions or molecules, understanding the influence that the synthesis parameters and additives have on the crystal growth is of great importance.

Proposed Work:

The topic to be addressed will involve the preparation of titania powder through the MSS method. Low temperature MSS and high temperature MSS will be performed to have a control on the anatase into rutile phase transformation and the influence of some additives will be investigated.6 The candidate will characterize the material mainly by means of SEM, XRD and Raman spectroscopy.

References:

1. Kimura, T. Molten Salt Synthesis of Ceramic Powders. in Advances in Ceramics – Synthesis and Characterization, Processing and Specific Applications (ed. Sikalidis, C.) 75–100 (InTech, 2011). doi:10.5772/20472

2. Reddy, M. V. et al. Low temperature molten salt synthesis of anatase TiO2 and its electrochemical properties. Solid State Ionics 262, 120–123 (2014).

3. Roy, B., Ahrenkiel, S. P. & Fuierer, P. A. Controlling the size and morphology of TiO2 powder by molten and solid salt synthesis. J. Am. Ceram. Soc. 91, 2455–2463 (2008).

4. Xu, J. et al. Molten salt assisted synthesis of black titania hexagonal nanosheets with tuneable phase composition and morphology. RSC Adv. 5, 85928–85932 (2015).

5. Liu, G. et al. Titanium dioxide crystals with tailored facets. Chem. Rev. 114, 9559–9612 (2014).

6. Beyene, A. M., Baek, C., Jung, W. K., Ragupathy, P. & Kim, D. K. Understanding the role of oxygen ion (O2−) activity in 1-D crystal growth of rutile TiO2 in molten salts. CrystEngComm 20, 487–495 (2018).

Contact:

Dipl.-Ing. Dario De Carolis