Elsevier

Materials Research Bulletin

Volume 68, August 2015, Pages 216-220
Materials Research Bulletin

Oriented and ordered mesoporous ZrO2/TiO2 fibers with well-organized linear and spring structure

https://doi.org/10.1016/j.materresbull.2015.03.043Get rights and content

Highlights

  • The ZrO2/TiO2 fibers were prepared by EISA process combined with steam heat-treatment.

  • The mesoporous ZrO2/TiO2 fibers have well-organized linear and spring structure.

  • The fibers were composed of oval rod nanocrystals of ZrTiO4.

Abstract

The ultra-stable order mesoporous ZrO2/TiO2 fibers with well-organized linear and spring structure and large surface areas under higher temperatures were prepared by a (simple evaporation-induced assembly) EISA process. The preparation, microstructures and formation processes were characterized by Fourier transformation infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption–absorption measurements. The fibers take on pinstripe configuration which is very orderly along or perpendicular to the axial direction of the fibers. The diameters of the pinstripe are in the region of 200–400 nm and arranges regularly, which are composed of oval rod nanocrystals of ZrTiO4.

Graphical abstract

The ultra-stable order mesoporous ZrO2/TiO2 fibers with well-organized linear and spring structure and large surface area under higher temperatures were prepared by a simple EISA process.

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Introduction

Ordered mesoporous transition-metal (TM) oxides synthesized through the self-assembly of amphiphilic organic molecules are of particular interest for both fundamental nanoscience and practical uses because of the unique porosities (high surface area, large pore volume and periodic mesopore) and the variable composition of the frameworks [1], [2], [3], [4], [5], [6], [7]. A wide variety of potential applications using ordered mesoporous TM oxides to optical, electric, catalytic and magnetic devices require the fabrication in various morphologies such as films and fibers. Fibrous morphology will show interesting chemical and physical properties depending on the structures, length and diameters of the fibers.

Among the developed methods, the so-called evaporation-induced self-assembly (EISA) is one that has been proven to be especially well-adapted to the design of TM oxide based mesoporous materials [8], [9], [10], [11]. During the synthesis process, the inorganic condensation of the precursor takes place at the interfaces of the surfactant self-assembled supramolecular structures, which create the mesostructured metal-oxo/polymer hybrid. When the solvents were evaporated and the spinnable sol was formed, and the precursor fibers could be fabricated by certain techniques (e.g., hand draw, electrospinning, dry spinning, wet spinning). Recently, the zirconium titanate fibers composed of tightly connected nano-particles without any templates were obtained through sol–gel method combined with dry-spinning by our group [12], and the mesoporous zirconia fibers and silica-supported zirconia fibers were fabricated through EISA process used P123 as the template [13], [14]. The ordered mesoporous materials possess extraordinarily large surface areas and well-arranged channels or pores that can greatly facilitate mass diffusion within frameworks or carrying other functional materials. More importantly, the ordered frame-work were obtained during the removal of the template, but it inevitably undergoes intense reorganization under the higher temperature for crystallization, which results in shrinkage and even collapse of mesostructures [15].

In this paper, we demonstrate a simple EISA process to prepare ultra-stable ordered mesoporous ZrO2/TiO2 fibers with well-organized linear and spring structure and large surface area under higher temperatures. The morphology, formation process and possible mechanism were analyzed by FTIR, XRD, SEM, TEM and so on.

Section snippets

Materials and preparation of the fibers

Zirconium source was using polyacetylacetonatozirconium (PAZ), which was synthesized by our group [16]. Triblock co-polymer Pluronic P123 (PEO20-PPO70-PEO20) and tetrabutyl titanate (TBOT) are all of AR grade.

In the typical synthesis, 5 g PAZ was dissolved in the 30 ml absolute ethanol, and 6.6 ml TBOT was added in to the above solution dropwise with vigorous stirring (the molar ratio of PAZ and TBOT was 1:1). The golden yellow solution was formed and 5 g P123 was added to the mixture solution and

Hydrolysis–condensation process of the fibers

From the FTIR curves of Fig. 2(a), it can be seen that all the absorption peaks of the CH3, Csingle bondC, Cdouble bondO and absorbed water gradually get weak with the temperature increasing. It means that the absorbed water and alkoxyl groups are effectively reduced when the fibers are pretreated to 200 °C and fully removed up to 400 °C. The absorption bands at 650 cm−1 and 460 cm−1 are attributed to the characteristic vibration of Tisingle bondOsingle bondTi and Zrsingle bondOsingle bondZr vibration, respectively, which indicates the formation of crystalline

Conclusions

The mesoporous ZrO2/TiO2 fibers with well-organized linear and spring structures can be fabricated in large scale by simple EISA process combined with water vapor heat-treatment. The fibers were with two different ordered structures. One is the pinstripe configuration and the pinstripe is very orderly along or perpendicular to the axial direction of the fibers. The diameters of the pinstripe shape are in the region of 200–400 nm and arrange regularly, which is composed of oval rod nanocrystals.

Acknowledgements

The authors acknowledge the financial support of the National Natural Science Foundations (Grant nos. 51472144, 51372140and 51102155), the Research Fund for the Doctoral Program of Higher Education (RFDP, 20110131120018), the Youth Scientist Fund of Shandong Province (BS2011CL025).

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