Anatase TiO2 single crystal hollow nanoparticles: their facile synthesis and high-performance in dye-sensitized solar cells

In this paper, we successfully synthesized anatase TiO2 hierarchical microspheres (S0), anatase TiO2 sub-micro hollow mesospheres (S50), anatase TiO2 single crystal hollow nanoparticles (S100), nanoparticles (S250) and (S500) by using different amounts of hydrofluoric acid (HF) versus titanium n-tetrabutoxide (TBT) and acetic acid (AcOH). The structure and morphology of the as-prepared materials were confirmed by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The DSSCs (dye-sensitized solar cells) based on anatase single crystal hollow TiO2 nanoparticles (S100) as a photoanode showed an efficient power conversion efficiency of 8.94% along with a current density of 17.39 mA cm-2 and an open circuit voltage of 778 mV, which is higher than the DSSCs based on S0 (8.10%), S50 (8.57%), S250 (7.25%) and S500 (6.12%). The high performance of S100 as a DSSC is attributed to their hollow structure which might help to harvest more light, higher light scattering and trapping abilities and comparatively higher surface area. Therefore, we can expect that our materials are promising for assembling superior photoelectrodes for future preparation of highly-efficient DSSCs and may lead to applications for energy storage, water splitting, catalysis, and gas sensing.