Supersaturation-Controlled Shape Evolution of α-Fe₂O₃ Nanocrystals and Their Facet-Dependent Catalytic and Sensing Properties

Abstract

Surface engineering of crystals at nanoscale level by precisely and rationally exposing specific facets proved to be highly effective in enhancing the performance of inorganic functional nanocrystals. To do so, a comprehensive understanding of the growth mechanism was of great importance. By using hematite (α-Fe2O3) as an example, in this paper we demonstrated high effectiveness of controlling supersaturation of growth monomers in engineering the exposed facets of nanocrystals. Under surfactant-free hydrothermal conditions, a series of morphology evolution of α-Fe2O3 nanocrystals from {012} faceted pseudocubes to {113} faceted hexagonal bipyramids and {001} faceted nanoplates were successfully activated through concentration-, reaction time-, and solvent-dependent hydrolysis of ferric acetylacetonate. High supersaturation was eventually proven to be conducive to the formation of facets with high surface energy. Furthermore, the α-Fe2O3 nanocrystals enclosed with facets of high surface energy exhibited excellent catalytic activity and gas-sensing ability. The present work will deepen our understanding of thermodynamics and kinetic control over the morphology of nanocrystals as well as our understanding of surface-related performance of inorganic functional nanocrystals.

Morphology evolution of NaTaO3 submicrometer single-crystals: from cubes to quasi-spheres

“…Therefore, the exposed surfaces and the morphologies of crystallites can be controlled by varying the supersaturation of the crystal growth units. In our previous papers, it was discussed that the introduction of a poor solvent increased the supersaturation [8,20]. Inspired by these preceding reports, we introduced the supersaturation strategy into the controllable growth of NaTaO 3 crystal.…”

Unique Crystallization of Fullerenes: Fullerene Flowers

“…S8). A higher ratio results in larger crystals because it reduces the number of seeds by decreasing the supersaturation level672425.…”

Renewable chitin from marine sponge as a thermostable biological template for hydrothermal synthesis of hematite nanospheres using principles of extreme biomimetics

“…A saturated solution was chosen so as to mimic the biomineralization of microbal organisms in hydrothermal fluids caused by supersaturation of the water with various minerals [37]. Moreover, tuning of saturation level of Fe source gives the possibility to control the morphology of obtained nanoparticles [38].…”