Fabricating fiber, rice and leaf-shaped TiO2 by tuning the chemistry between TiO2 and the polymer during electrospinning

Abstract

Electrospinning is a facile technique for the fabrication of nanofibers (one-dimensional, 1D, nanostructures) of metals, metal oxides and polymers on a commercial scale which find applications in the fields of energy (dye-sensitized solar cells, Li-ion batteries, fuel cells, etc.), healthcare, environmental engineering and biotechnology (membranes and filters). While electrospinning polymer solutions results in polymer nanofibers, metal oxide nanofibers (say of TiO₂) are made by electrospinning a TiO₂ precursor along with a polymer into composite nanofibers and subsequently removing the polymer by a sintering process. However, we have found that the morphology of the electrospun TiO₂ depends on the chemical nature of the polymer involved and more precisely the chemical interactions between the polymer and the TiO₂ during the sintering process. When the polymer is changed from polyvinyl pyrrolidone (PVP) to polyvinyl acetate (PVAc) to a mixture of PVP and PVAc, the morphology of the TiO₂ varies from continuous fibre to rice-shaped to leaf-shaped. The present manuscript explores the chemistry between the TiO₂ and the above mentioned polymers which results in the structural anisotropy of the electrospun TiO₂. The electrospun metal oxides are useful for energy and environmental applications.