Microsphere Assembly of TiO2 Rectangular Nanotubes: Facile Fabrication and Photovoltaic Property

Novel hierarchical microspheres constructed with TiO2 rectangular nanotubes (TRTMs) were fabricated via a facile route. The obtained samples were investigated by the field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The FESEM results showed that the solid cuboids precursor become rectangular and hollow TiO2 nanotube after calcination at 500 degrees C for 3 h. The XRD spectra and TEM results confirmed that crystalline anatase TiO2 was formed. Meanwhile, a possible mechanism for the formation of the hollow structure was also briefly proposed. The prepared TRTMs were applied as the scattering layer on the top of Deguss P-25 nanoparticles thin film and were then used as the photoanode of dye-sensitized solar cell (DSSCs). This prepared photoanode had enhanced light harvesting capabilities due to the ability to reflect the transmission light into the P-25 sub-layer, which ultimately led to an increase in the electron density. The EIS spectra showed that the optimized photoanode using TRTMs as the scattering layer is benificial for electron transport due to the synergistic effect of the excellent light-scattering ability of TRTMs and the relatively high dye adsorption amount of P-25 sublayer. An overall conversion efficiency of 7.34% was obtained for the optimized bi-layer photoanode, and a 40.9% increment in conversion efficiency was achieved even though the dye adsorption is 45.8% lower than that of pure P-25 photoanode. (C) 2016 Elsevier Ltd. All rights reserved.