Ionic liquid-assisted synthesis of F-doped titanium dioxide nanomaterials with high surface area for multi-functional catalytic and photocatalytic applications

Abstract

Ionic liquid (IL) assisted syntheses of ultrareactive F-doped mesoporous aggregates of titanium dioxide nanoparticles have been studied using different synthetic methods in order to obtain non-toxic, highly versatile systems able to combine the high photocatalytic activity of the F-doping with a high surface area, to be applied in different catalytic and photocatalytic processes of environmental interest. The synthesized materials were characterized by various techniques, showing that they consist of mesoporous aggregates of F-doped anatase nanoparticles with surface areas of up to ca. 200 m2/g, which, together with the incorporation of ultrareactive (001) anatase facets promoted by doping, made the synthesized titanium dioxide nanomaterials very active in photocatalytic processes. The studies systems showed in the photocatalytic degradation of organic contaminants degradations of up to 96 % of concentrated solutions of methylene blue and common emerging pollutants such as ciprofloxacin (90 % degradation) and naproxen (79 % degradation) under UV light (300 W) in 10 min. In addition, when doped with palladium nanoparticles they became effective heterogeneous catalysts in Suzuki–Miyaura C–C coupling reactions giving good to excellent halide conversions (between 60–99 % for the formation of biphenyl derivatives) and high TOF values (up to 120 h−1) at short reaction times and good degree of recyclability. In addition, the Pd- and Pt-doped systems were also tested in the green process of hydrogen production by methanol photoreforming, showing a good accumulated hydrogen amount of ca. 75 mmol after 400 min with moderate photonic efficiencies of up to ca. 4.1 %.