Separation of anatase phase from commercially available P25 powder for dye-sensitized solar cells

The anatase and rutile phases existing in commercially available P25 powder were separated according to their different particle size and chemical affinity. Firstly, electrical double layer was established on TiO2 surface to achieve a highly dispersed TiO2 colloid due to electrostatic repulsive forces. Additionally, strong electrolyte HCl was added to neutralize the weak electrical double layer of rutile particles, and makes them precipitated from TiO2 colloid priorly by centrifugal force. As the amount of HCl increased from 0 to 2 ml, the anatase percent increased from 83.2 to 100%, the diameter decreased from 30.0 to 19.7 nm while the specific surface increased from 52.9 to 76.3 m2/g. Further, the conversion efficiency of dye-sensitized solar cells fabricated from the separated powder increased from 8.52 to 10.1% under 100 mW cm−2 AM 1.5 illumination.