Fabrication of Hollow and Porous Tin-Doped Indium Oxide Nanofibers and Microtubes via a Gas Jet Fiber Spinning Process.

Monoj Ghosh,Sadhan C Jana

doi:10.3390/ma13071539

Abstract

We report the morphologies of tin-doped indium oxide (ITO) hollow microtubes and porous nanofibers produced from precursor solutions of polyvinylpyrrolidone (PVP), indium chloride (InCl3), and stannic chloride (SnCl4). The polymer precursor fibers are produced via a facile gas jet fiber (GJF) spinning process and subsequently calcined to produce ITO materials. The morphology shows strong dependence on heating rate in calcination step. Solid porous ITO nanofibers result from slow heating rates while hollow tubular ITO microfibers with porous shells are produced at high heating rates when calcined at a peak temperature of 700 °C. The mechanisms of formation of different morphological forms are proposed. The ITO fibers are characterized using several microscopy tools and thermogravimetric analysis. The concentration of inorganic salts in precursor solution is identified as a key factor in determining the porosity of the shell in hollow fibers. The data presented in this paper show that GJF method may be suitable for fabrication of hollow and multi-tubular metal oxide nanofibers from other inorganic precursor materials.

Highlights

One dimensional (1-D) nanostructures of inorganic oxides namely nanofibers [1,2,3,4,5,6,7], nanorods [6], nanotubes [7], or nanowires [8] present unique optical, electronic, magnetic, sensor, and opto-electronic properties, and are suitable for many applications
Zhang et al [14] synthesized hollow TiO2 nanofibers with surface area as high as 118 m2 g−1 using a two-step synthesis approach consisting of electrospinning of titanium isopropoxide (Ti(OiPr)4 )
With two immiscible polymers polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell needle followed by template removal via annealing at 450 ◦ C

Summary

Introduction

One dimensional (1-D) nanostructures of inorganic oxides namely nanofibers [1,2,3,4,5,6,7], nanorods [6], nanotubes [7], or nanowires [8] present unique optical, electronic, magnetic, sensor, and opto-electronic properties, and are suitable for many applications. A number of methods have emerged reporting the synthesis of inorganic oxide nanotubes or nanofibers, namely template synthesis [16], co-axial electrospinning techniques [17], microfluidic compound jet electrospinning [18], anodization technique [19], and hydrothermal method [20]. Zhang et al [14] synthesized hollow TiO2 nanofibers with surface area as high as 118 m2 g−1 using a two-step synthesis approach consisting of electrospinning of titanium isopropoxide (Ti(OiPr) ). With two immiscible polymers polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) using a core-shell needle followed by template removal via annealing at 450 ◦ C. The idea of co-axial electrospinning technique was utilized later for the fabrication of hollow TiO2 nanostructure from a PVP solution containing Ti(OiPr) and mineral oil, followed by selective removal of the liquid core and calcination [17]

Methods

Results

Conclusion