Aqueous Solution Synthesis of Crystalline Anatase Nanocolloids for the Fabrication of DSC Photoanodes

The production of anatase nanocolloids via a novel aqueous solution synthesis method is described. The process involves forced hydrolysis of 0.2 M TiCl4 aqueous solution at low temperature (80 degrees C) leading to fast nucleation of TiO2 anatase nanoparticles (4-5 nm). The isolated nanopowders were found to consist predominantly of anatase as the major phase (similar to 85 wt %), possess a very high surface area (up to 250-350 m(2)/g), and a relatively elevated surface hydroxyl content in comparison with the P25 reference material. Single-layer (similar to 12 mu m thick) photoanodes prepared with aqueous-synthesized powders were found to have a specific surface area of similar to 130 m(2)/g and the anatase nanocrystallites to have grown to similar to 12 nm and assume a higher degree of crystallinity but still carry similar to 1.5% surface OH groups. The pore size of the film was determined to be similar to 8 nm. By comparison, the film prepared with P25 nanoparticles had the following properties: 50 m(2)/g, 30 nm crystallite size, 0.2% surface OH, and 25 nm pore size. Dye-sensitized solar cell (DSC) devices assembled with the newly fabricated photoanodes showed equivalent photoelectrochemical performance [power conversion efficiency] eta, short-circuit current voltage I-sc, open-circuit voltage V-oc, and Fill Factor (FF)] to cells prepared using the benchmark P25 titania powder. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3529238] All rights reserved.