RESUMEN

Borate toxicity is a concern in agriculture since a high level of borates may likely exist in irrigation water systems. In this research, transmission infrared spectroscopy and X-ray photoelectron spectroscopy are employed to study the thermal and photochemical reactions of isopropoxy tetramethyl dioxaborolane (ITDB) on TiO2, with the aid of density functional theory calculations. In addition, the possibility for the formation of a boron-modified TiO2 (B/TiO2) surface, using ITDB as the boron source, is explored and the photocatalytic activity of the B/TiO2 is tested. After adsorption of ITDB on TiO2 at 35 °C and heating the surface to a temperature higher than ∼200 °C in a vacuum, the surface is found to be covered with both the organic components of OC(CH3)2-C(CH3)2O and OCH(CH3)2 and the inorganic components of (TiO2)BO and Ti-B-O. The organic intermediates can be further thermally transformed into pinacolone and acetone; however, the inorganic parts exist at 400 °C, forming a boron-modified surface. The thermal decomposition of ITDB is proposed to be initiated by breaking one B-O bond, forming -OC(CH3)2-C(CH3)2O-B-OCH(CH3)2 on the surface. In the case of photoreaction, the ITDB on TiO2 decomposes under photoirradiation at 325 nm to form acetone. The boron-modified TiO2 surface can absorb visible light, likely due to the presence of new states in the band gap, and shows a photocatalytical activity in degrading methylene blue, under 500 nm irradiation in air.