Photodegradation of dye acridine yellow on the surface of mesoporous TiO2, SiO2/TiO2 and SiO2 films: spectroscopic and theoretical studies

Electronic spectra and LDI mass spectra changes accompanying photodegradation of acridine yellow (AY) adsorbed on the surface of prepared via templated sol–gel synthesis TiO2, SiO2, and TiO2/SiO2 mesoporous films have been investigated and the main photodegradation products have been determined. The results of calculations show the adsorption energy of the molecular state of AY to be the greatest for the complex with titania–silica where Lewis acidic sites are present, the smallest one being related to the complex with titania what corresponds to the experimental data. Effectiveness of acridine yellow photodegradation on the surfaces of mesoporous films under UV irradiation increases in a row SiO2/TiO2/SiO2/TiO2. Electronic and laser desorption/ ionization mass spectra and theoretical modeling give evidence that efficient photobleach of AY localized at the surface of anatase films proceeds through the following steps: 1—N-demethylation/deamination; 2—photodimerization; 3—photodegradation.