Fabrication of a silica/titania hollow nanorod and its electroresponsive activity

Abstract

In this study, a 1D oriented hollow SiO 2 /TiO 2 (HST) rod-like material was successfully fabricated via a sequential combination of sol-gel use, TiO 2 incorporation, and a sonication-mediated etching and redeposition method. This carefully manipulated new material has numerous advantageous physical and intrinsic properties, such as increased surface area, pore volume, interfacial polarization, and dielectric properties introduced from each synthetic step. The synthesized HST rod was adopted as an electrorheological (ER) material for practical examination of these characteristics. The HST rod materials exhibited 1.5-and 3-fold higher ER performance than a non-metal SiO 2 rod and a non-hollow SiO 2 /TiO 2 core/shell (ST/CS) rod, which are interim synthetic steps. Moreover, the HST rod exhibited remarkable 6-fold increased ER efficiency relative to a sphere-shaped hollow SiO 2 /TiO 2 particle synthesized using a similar experimental method. These notable enhancements in ER performance are attributed to incorporation of the experimentally designed characteristics of the HST rod: 1D structure, metal oxide incorporation, and creation of a hollow cavity. For future study, we expect that these versatile HST rod materials can be applied in a range of fields including drug delivery, photo-catalysis, and as building blocks.SiO 2 rod, ST/CS rod, and HST rod (L/D ¼ 3), (2) TEM micrographs HCl untreated and calcined SiO 2 rod and resulting HST rod, (3) TEM micrographs of shell thickness controlled HST rod, (4) TEM micrographs of SiO 2 rod, ST/CS rod, and HST materials with varying aspect ratio (L/D ¼ 1, 2, 6), (5) low-magnied TEM micrographs of various HST materials (L/D ¼ 1, 2, 6), (6) physical parameters of various HST materials, (7) porosity, pore volume, and BET surface area of HST rod (L/D ¼ 3), (8) EDS analysis of SiO 2 rod, ST/CS rod, and HST rod (L/D ¼ 3), (9) STEM elemental mapping of SiO 2 rod (L/D ¼ 3), (10) FT-IR spectra and XRD pattern of SiO 2 rod, ST/CS rod, and HST rod (L/D ¼ 3), (11) FT-IR spectra of HCl treated and untreated SiO 2 rod, (12) atomic compositions of various HST materials (L/D ¼ 1, 2, 6), (13) shear stress of HST material-based ER uids with varying aspect ratio (L/D ¼ 1, 2, 6), (14) dielectric properties of HST sphere. See

Synthesis of Hierarchical Silica/Titania Hollow Nanoparticles and Their Enhanced Electroresponsive Activity

“…43 Previous studies have reported that materials with large Δε and short λ exhibit better ER performances under an applied E field. 6,9 Specifically, Δε can be determined by referring to the differences between fictitious (ε 0 , f → 0) and static (ε ∞ , f → ∞) dielectric constants, thus providing information on the polarizability of materials. The determined Δε values for WSNs, W-STCSs, and W-HNPs were 1.12, 2.11, and 2.42, respectively.…”

“…The ER performance is greatly affected by the dielectric properties and dispersion stability of the materials. 6 The former relates to the polarization ability of the material and the latter to the stability of the materials in the dispersing medium. Numerous polarizable materials, including organic, inorganic, metal, carbonaceous, and polymeric ones (and their composites), have been evaluated as ER materials.…”

Electroresponsive Performances of Ecoresorbable Smart Fluids Consisting of Various Plant‐Derived Carrier Liquids

“…Judging from the EDS results, the ST HNPs were composed of Si, Ti, and O atoms. Notably, Si atoms remained after the etching process due to the redeposition process resulting in the SiO 2 /TiO 2 composites [7,36] . In the case of Mg‐doped ST HNPs, Mg was detected along with Si, Ti, and O over the entire surface of the particles, which indicates that ST HNPs were successfully doped with Mg and well‐distributed over the surface (Figure S3).…”

“…Yoon et al. fabricated silica/titania hollow nanorods with an inner cavity to lower the density [7] . A high dielectric constant can be achieved by the following methods: increasing the active surface area of the particle, coating the particle with conducting polymer, modifying polar groups, fabricating a multilayered structure, and metal‐doping.…”

Graphene Oxide and Its Inorganic Composites: Fabrication and Electrorheological Response

“…The influence of geometrical morphologies on the ER characteristics has always been an important topic. Many studies have shown that rod-shaped, tubular, and fibrous ER materials usually exhibit a stronger ER effect than granular materials [61,62,63]. In addition, ER materials with a high aspect ratio can exhibit better sedimentation stability [64].…”