A Versatile Kinetics-Controlled Coating Method To Construct Uniform Porous TiO₂ Shells for Multifunctional Core–Shell Structures

Abstract

The development of a simple and reproducible route to prepare uniform core@TiO(2) structures is urgent for realizing multifunctional responses and harnessing multiple interfaces for new or enhanced functionalities. Here, we report a versatile kinetics-controlled coating method to construct uniform porous TiO(2) shells for multifunctional core-shell structures. By simply controlling the kinetics of hydrolysis and condensation of tetrabutyl titanate (TBOT) in ethanol/ammonia mixtures, uniform porous TiO(2) shell core-shell structures can be prepared with variable diameter, geometry, and composition as a core (e.g., α-Fe(2)O(3) ellipsoids, Fe(3)O(4) spheres, SiO(2) spheres, graphene oxide nanosheets, and carbon nanospheres). This method is very simple and reproducible, yet important, which allows an easy control over the thickness of TiO(2) shells from 0 to ~25, ~45, and ~70 nm. Moreover, the TiO(2) shells possess large mesoporosities and a uniform pore size of ~2.5 nm, and can be easily crystallized into anatase phase without changing the uniform core-shell structures.

Controlled deposition of titanium oxide overcoats by non-hydrolytic sol gel for improved catalyst selectivity and stability

“…However, while high levels of control have been reported for SiO 2 deposition, which benefits from kinetically slow hydrolysis/condensation [13], highly reactive titanium oxide precursors prevent controlled deposition of thin oxide layers (<50 nm). Although remarkable results were achieved by controlling the kinetics of condensation with catalysis [14] or chelating agents [15], deposition of multiple oxide layers on challenging substrates such as high surface area mesoporous materials or supported metal nanoparticles remains a challenge [16][17][18][19][20].…”

Synthesis And Characterization Of SiO2, SnO2 And TiO2 Metal Oxide Shells Covering Cu2O Particles

“…The uniform porous TiO 2 shells of the core-shell structures were prepared via the sol-gel method [9]. The Cu 2 O (75 mg) nanoparticles were dispersed in absolute ethanol (100 mL), and mixed with concentrated NH 4 OH solution (0.3 mL, 1.4 wt%) with stirring for 15 min.…”

“…SiO 2 shells can significantly modify the qualities of the core materials due to physical properties that include such as optical capabilities, biocompatibility and environmental stability [6]. Another raw material, titanium oxide (TiO 2 ), is a common choice for use as a photocatalyst due not only to its photocatalytic attributes, but also to its low cost [8][9]. Previously, great effort had been directed toward synthesis of core@TiO 2 structures [8].…”

“…Previously, great effort had been directed toward synthesis of core@TiO 2 structures [8]. For example, Caruso and co-workers introduced a layer-by-layer self-assembly strategy for coating TiO 2 , which was realized by surface electrostatic interactions [9]. In this work is described a means of improving the chemical stability of Cu 2 O@SiO 2 , Cu 2 O@SnO 2 and Cu 2 O@TiO 2 materials.…”

Broadening microwave absorption via a multi-domain structure

“…For example, the protective-shell strategies, i.e., coating with organic species or inorganic layers, have been developed to chemically stabilize the naked nanomaterials against the degradation of properties. [11][12][13][14][15][16] In addition, owing to the fact that the size and shape-dependent anisotropy energy dominates the magnetic properties, many attempts have been oriented towards the hierarchical-structure design of materials. [17][18][19][20][21][22][23][24] Briefly, although the properties of nanomaterials can be retained or enhanced by the above-mentioned strategies, it is still difficult to widen the microwave absorption band.…”