Functionalization of anatase nanoparticles with Glutaric acid and their photochemical and photocatalytic properties under visible light

Charge transfer complexes (CTCs) formed between TiO2 and chelating ligands have attracted extensive attention for photocatalytic applications under visible radiation due to their increased visible light absorption. Different TiO2-based CTCs have been widely studied. However, the sensitization of TiO2 to visible light by functionalization with glutaric acid (TiO2-GA) and its photocatalytic performance under visible light radiation have not yet been investigated, as far as the authors know. In this study, visible-light-sensitive TiO2-GA nanomaterials were synthesized via sol-gel and calcined under static air at 270 degrees C. The as-prepared TiO2-GA CTCs were characterized by XRPD, FTIR, TGA, DRS, PL, EPR and XPS techniques. FTIR data supported the formation of the CTC through bidentate chelating interaction between TiO2 and GA. TiO2-GA CTCs calcined at 270 degrees C under static air exhibited a long absorption tail in the visible light spectrum mainly due to the formation of F+ centers. The high content of GA molecules bounded to the TiO2 surface was not beneficial for photocatalytic performance of the TiO2-GA CTCs, since these molecules reduced the active sites on the nanostructure surface, resulting in a lower production of superoxide radicals by the TiO2-GA CTCs. Our findings indicated that: a) TiO2-GA CTCs are capable to degrade antibiotic liquid pollutants via interactions with superoxide radicals and also, b) provided fundamental insights into the influence of bulk Ti3+ defects and bulk oxygen vacancies on photocatalytic performance and photochemical properties of TiO2-based CTCs.