Evaluation of photoconductive and photoelectrochemical properties of mesoporous nanocrystalline TiO2 powders and films prepared in acidic and alkaline media

Abstract

Nanocomposite TiO2 powders were prepared via hydrothermal route using titanium(IV) butoxide as starting material at different pH media. In particular, three alkaline media composed of ammonium carbonate, ammonium bicarbonate and urea were used as modulators of the TiO2 nanostructure. Besides, sulfuric acid was also used succeeding an acidic environment for the growth of TiO2 nanoparticles. The structural properties of powders made either in acidic or alkaline environment were examined with microscopy techniques (FE-SEM), X-ray diffraction patterns (XRD), porosimetry (BET) and FTIR spectroscopy. TiO2 films were fabricated by suitably modifying the synthesized powders in the form of easily handled pastes. The powders were evaluated to their photoconductivity properties while films were sensitized with N719 ruthenium dye and employed as photoanodes in quasi-solid state dye sensitized solar cells (DSSCs). The cells were characterized in terms of their electrical and electrochemical characteristics using impedance spectroscopy. The overall performance of the solar cells employing TiO2 films prepared in acidic or alkaline environment was higher than that recorded for commercially obtained TiO2 powder (Degussa-P25) with a maximum difference of 16% in the case of TiO2 made in acidic environment.