Evaluation of the anatase/rutile phase composition influence on the photocatalytic performances of mesoporous TiO2 powders

We investigated the influence of the microstructure, texture and the relative amount of anatase and rutile phases on the photoelectrocatalytic H2 evolution over mesoporous TiO2 (m-TiO2). This study was carried out by means of ex-situ powder X-ray diffraction (XRPD), N2 physisorption, transmission electron microscopy (TEM), and photoelectrolysis measurements. The synthesis of nanocrystalline TiO2 powders with different anatase/rutile weight ratios was successfully approached by evaporation-induced self assembly (EISA) method simply varying the volume amount of TiCl4 and Ti(OBu)4 (acid-base pair) as metal precursors. In particular, m-TiO2 with anatase/rutile weight ratios similar to commercial TiO2 (P25) was obtained. The microstructure, texture and photocatalytic properties toward hydrogen evolution reaction (HER) of the as-synthesized TiO2 were compared with commercial P25. Interestingly, the m-TiO2 with a high surface area of 196m2/g, uniform pore size and 87/13 anatase/rutile weight ratio, showed a significant increase in the photoactivity with respect to the powders richer in either anatase or rutile phases. Furthermore, it was claimed that the crystallinity and specific surface area play a key role on the photocatalytic activity of the synthesized m-TiO2 samples