A facile approach for high surface area electrospun TiO2 nanostructures for photovoltaic and photocatalytic applications

Abstract

A rice-shaped TiO₂–ZnO composite was prepared by electrospinning a mixture comprising the precursors of TiO₂ and ZnO in polyvinyl acetate polymer dissolved in N,N-dimethyl acetamide. The electrospun nanofibers upon heat treatment in air resulted in collapse of the continuous fiber morphology and the formation of the rice-shaped TiO₂–ZnO composite. The TiO₂–ZnO composite was then treated with dilute acetic acid under hydrothermal conditions to etch ZnO from the TiO₂–ZnO composite to get coral-shaped anisotropic TiO₂. The structural anisotropy of TiO₂ produced by the selective etching of ZnO resulted in a high surface area of 148 m² g⁻¹ for the TiO₂. The initial and final materials were characterized by scanning electron microscopy, transmission electron microscopy, Raman and XPS spectroscopies, powder X-ray diffraction and BET surface area measurements. The utility of the anisotropic TiO₂ in photovoltaics and photocatalysis was explored. Dye-sensitized solar cells fabricated using the TiO₂ showed a conversion efficiency of 6.54% as against 4.8% for a control experiment with the rice-shaped TiO₂. The anisotropic TiO₂ also showed good photocatalysis in the degradation of methyl orange dye and phenol.