Synthesis of lustering two-dimensional alpha-MoO3 van der Waals crystals by TiO2 assisted selective facet passivation

Abstract

Large-sized alpha-MoO3 nanoplates with 10-100 mu m were synthesized by introduction of titanium tetra isopropoxide as TiO2 precursor in hydrothermal solution chemistry. During the hydrothermal synthesis, the TiO2 can be selectively deposited on the (001) facets of h-MoO3 hexagonal rods and on the (001) and/or (010) facet of alpha-MoO3 re-growing crystals due to the small lattice mismatch between them. Owing to the TiO2 passivation of the surface of h-MoO3 rods, the h-MoO3 rods are changed to MoO3 tubes because the h-MoO3 are dissolved from the inner part of the TiO2 passivated h-MoO3 rods. The TiO2-passivated (001) facets of h-MoO3 rods act as templates for the re-growth of alpha-MoO3 and consequently produced rectangle-shaped alpha-MoO3 nanoplates. Simultaneously, the TiO2 passivated on the (001) and/or (010) facet of the re-growing alpha-MoO3 crystals inhibits the preferred crystal growth to [001] direction and promoted the crystal growth to [100] direction, thereby yielding plate-shaped alpha-MoO3. The small alpha-MoO(3 )nanoplates and rectangle-shaped ones are further grown to larger nanoplates by attachment process and/or continuous growth. (C) 2020 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.