Mesoporous Titania powders: the role of precursors, ligand addition and calcination rate on their morphology, crystalline structure and photocatalytic activity

We evaluate the influence of the use of different titania precursors, calcination
rate, and ligand addition on the morphology, texture and phase content of synthesized
mesoporous titania samples, parameters which, in turn, can play a key role in titania
photocatalytic performances. The powders, obtained through the evaporation-induced
self-assembly method, are characterized by means of ex situ X-Ray Powder Diffraction
(XRPD) measurements, N2 physisorption isotherms and transmission electron microscopy.
The precursors are selected basing on two different approaches: the acid-base pair, using
TiCl4 and Ti(OBu)4, and a more classic route with Ti(OiPr)4 and HCl. For both precursors,
different specimens were prepared by resorting to different calcination rates and with and
without the addition of acetylacetone, that creates coordinated species with lower hydrolysis
rates, and with different calcination rates. Each sample was employed as photo anode and tested in the water splitting reaction by recording I-V curves and comparing the results with
commercial P25 powders. The complex data framework suggests that a narrow pore size
distribution, due to the use of acetylacetone, plays a major role in the photoactivity, leading
to a current density value higher than that of P25.