Tayloring the photocatalytical activity of anatase TiO2 thin film electrodes by three-dimensional mesoporosity

Mesoporous titanium dioxide (m-TiO2) thin film electrodes were synthesized by evaporation-induced self-assembly (EISA), utilizing a novel type of amphiphilic block copolymer as template. The ordered network of pores shows an accessible inner volume that results in a huge BET-surface and a distinct transparency. According to X-ray diffraction analyses the mesoporous films are highly crystalline after calcination at 550°C. 1D and 2D small-angle X-ray scattering and transmission electron microscopy investigations prove the high quality of the mesopore texture over micrometer-sized areas. These well-defined, crystalline m-TiO2 films show an increased photoactivity for overall water splitting and oxidation of formic acid as compared to porous films prepared in the same manner without a template. The performance of the electrodes was analyzed by measuring the photocurrent and the mass signal of liberated gas by electrochemical mass spectroscopy (EMS). These experiments reveal that film morphology have a great influence to the IV characteristic of photoelectrodes. An appropriate crystallization temperature is indispensable to obtain an optimum between crystallinity, morphology and photoactivity and to prevent collapse of the mesopore architecture. © (2010) Trans Tech Publications, Switzerland.