Molten Salt Hydrates in the Synthesis of TiO2 Flakes

Trang Q Tran; Weiqing Zheng; George Tsilomelekis

doi:10.1021/acsomega.9b02850

Molten Salt Hydrates in the Synthesis of TiO₂ Flakes

ACS Omega. 2019 Dec 3;4(25):21302-21310. doi: 10.1021/acsomega.9b02850. eCollection 2019 Dec 17.

Authors

Trang Q Tran¹, Weiqing Zheng², George Tsilomelekis¹

Affiliations

¹ Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States.
² Catalysis Center for Energy Innovation and Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, Delaware 19716, United States.

Abstract

Herein, we present a method for the preparation of titanium dioxide with a relatively large surface area, mesoporosity, and good thermal stability. We show that by utilizing molten salt hydrates (MSH) as non-trivial synthesis media, we prepare materials with thin, flake-like morphology with a large aspect ratio. The thickness of the synthesized flakes can be controlled by adjusting the salt/water (always in the MSH regime) and/or the salt/precursor molar ratio. The TiO₂ flakes appear to be formed via the aggregation of small TiO₂ nanoparticles (typically around 7-8 nm) in an apparent 2D morphology. We hypothesize that the ordered structure of water molecules within the ions of the salt in conjunction with the fast hydrolysis/condensation rates occurring in the presence of water of the precursor used are responsible for this agglomeration. We also report that the purity of materials (anatase vs brookite crystalline phase) appears to be a function of the LiBr/water ratio which is hypothesized to arise either from pH variation or due to lattice matching of the relevant orthorhombic structures (brookite and LiBr _x ·3H₂O). Discussion on the potential for scalability of the presented method is also highlighted in this article.