Synergetic effects in novel hydrogenated F-doped TiO₂ photocatalysts

Highlights: • Novel hydrogenated F-doped TiO₂. • UV, visible and infrared light absorption. • Large presence of surface active sites. • Inhibit electrons and holes recombination. • Superior photocatalytic activity. - Abstract: The synergistic effect between fluorine and hydrogen in hydrogenated F-doped TiO₂ photocatalysts is evaluated for the photocatalytic degradation of atrazine. The interaction between fluorine and hydrogen species in hydrogenated F-doped TiO₂ overcomes the limitations of individual F-doped TiO₂ and hydrogenated TiO₂ photocatalyst properties. Hydrogenated F-doped TiO₂ is photo-active under UV, visible and infrared light illumination with efficient electrons and holes separations. The optimized concentration of surface vacancies and Ti³⁺ centers coupled with enhanced surface hydrophilicity facilitates the production of surface-bound and free hydroxyl radicals. The surface of the catalyst contains =Ti−F, =Ti−OH, =Ti−O_vacancy and =Ti−H bonds as evidenced by XPS, Raman, FTIR and HR-TEM analysis. This combination also triggers the formation of new Ti³⁺ occupied states under the conduction band of hydrogenated F-doped TiO₂. Moreover, the change in the pore structure from cylindrical to slits and larger surface area facilitates surface charge interactions. The thermal stability is also enhanced and a single anatase phase is obtained. The size of the particles of hydrogenated F-doped TiO₂ is also uniform with defined and homogeneous crystal structure. This synergetic effect between fluorine and hydrogen opens up new alternatives in improving the properties of TiO₂ and its photocatalytic activity.