Anatase TiO2 Nanoparticles with Exposed {001} Facets for Efficient Dye-Sensitized Solar Cells

Anatase TiO 2 nanoparticles with exposed {001} facets were synthesized from Ti powder via a sequential hydrothermal reaction process. At the first-step hydrothermal reaction, H-titanate nanowires were obtained in NaOH solution with Ti powder and at second-step hydrothermal reaction, anatase TiO 2 nanoparticles with exposed {001} facets were formed in NH 4 F solution. If the second-step hydrothermal reaction was carried out in pure water, the H-titanate nanowires were decomposed into random shape anatase-TiO 2 nanostructures, as well as few impurity of H 2 Ti 8 O 17 phase and rutile TiO 2 phase. Then, the as-prepared TiO 2 nanostructures synthesized in NH 4 F solution and pure water were applied to the photoanodes of dye-sensitized solar cells (DSSCs), which exhibited power conversion efficiency (PCE) of 7.06% ( V OC of 0.756 V, J SC of 14.80 mA/cm 2 , FF of 0.631) and 3.47% ( V OC of 0.764 V, J SC of 6.86 mA/cm 2 , FF of 0.662), respectively. The outstanding performance of DSSCs based on anatase TiO 2 nanoparticles with exposed {001} facets was attributed to the high activity and large special surface area for excellent capacity of dye adsorption.