Annealing-free preparation of anatase TiO2 nanopopcorns on Ti foil via a hydrothermal process and their photocatalytic and photovoltaic applications

Abstract

Uniform and well-defined nanopopcorns of the tetragonal anatase TiO₂ having an average diameter of 670 nm have been facilely grown on Ti foil via a hydrothermal method and characterized by analyzing electron microscopic images and electron diffraction patterns as well as X-ray photoelectron, photoluminescence, and Raman spectra. The morphology of TiO₂ nanostructures on Ti foil has been controlled well by adjusting the volume ratio of H₂O₂ : HF : H₂O, VR(H₂O₂ : HF : H₂O). Truncated tetragonal pyramidal TiO₂ nanocrystals exposing the {001} and {101} facets have grown on the surface of TiO₂ nanostructures exposing the {001} facets to produce anatase TiO₂ nanopopcorns. Without being treated via any annealing process, our well-defined TiO₂ nanopopcorns on Ti foil have been directly employed for photocatalytic materials and dye-sensitized solar cells. Among our prepared samples, anatase TiO₂ nanopopcorns grown on Ti foil at a VR(H₂O₂ : HF : H₂O) of 1 : 1 : 1000 have shown the most reduced oxygen vacancy luminescence, the highest photocatalytic activity for the degradation of methylene blue, and the highest photovoltaic conversion efficiency of 3.98% as the working electrode of a dye-sensitized solar cell.