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This study examined the photoelectric conversion efficiency of the dye-sensitized solar cell (DSSC) when the surface of a nanometer-sized TiO 2 film, which was prepared using the solvothermal method, was modified by five acid compounds. The TiO 2 film exhibited an anatase structure with an average particle size in the range of 10-15 nm, and the maximum absorption band was shown in the UV-visible spectrum around 360 nm. The surface colors of the carboxylic acid-modified TiO 2 films were changed to light or dark with differing energy conversion efficiencies. Particularly, the conversion efficiency was considerably enhanced from approximately 6.25% for the non-modified TiO 2 film to approximately 7.50% for the film treated by acetic acid of 1.0 mole, with the N719 dye under 100 mW/cm 2 of simulated sunlight. FT-IR analysis of the films after N719 dye adsorption confirmed that the IR spectrum of the modified TiO 2 showed a sharp and strong band at 500 cm −1 , which was assigned to a metal-O bond, due to the formation of a new Ti-O bond between the O of COO − and the Ti atom, which was relatively weaker in the non-modified TiO 2 . Furthermore, these results were in agreement with an electrostatic force microscopy (EFM) study showing that the electrons were transferred rapidly to the surface of the acetic acid-modified TiO 2 film, compared with that on the nonmodified TiO 2 film.

To improve the ortho-or para-xylene selectivity via the isomerization of meta-xylene, the acid sites located on the external surface of zeolite Y crystals were neutralized by using the intrinsic mechanochemical method, which resulted in reduced coke formation. Zeolite Y crystals were mixed in an agate mortar with alkaline earth metal oxides supported on micro spherical non-porous silica. The catalytic performances into o-or p-xylene from the m-xylene isomerization reaction were enhanced, especially with either the CaO-or MgO-neutralized catalyst, as verified by adsorption of bipyridine, which could not access the pore channel due to its bulky molecular size. These consistent changes in the reaction performance could be ascribed to the decrease in the number of acid sites on the external surfaces.