A hierarchical Ag2O-nanoparticle/TiO2-nanotube composite derived from natural cellulose substance with enhanced photocatalytic performance

Abstract

A series of hierarchical Ag2O-nanoparticle/TiO2-nanotube heterostructured nanocomposites with varied Ag2O contents were fabricated by employing natural cellulose substance as the template. The nanocomposites possessed fine three-dimensional porous network structures, which were composed of TiO2 nanotubes and fine Ag2O nanoparticles that anchored on the surfaces. The composites exhibited enhanced photocatalytic performances in degrading different organic pollutants under ultraviolet light irradiation. The optimal Ag2O-NP/TiO2-NT nanocomposites exhibited apparent rate constants of 0.62, 0.37 and 0.39 min−1 in photocatalytic degrading methylene blue, Rhodamine B and norfloxacin, respectively; which were correspondingly 2.6, 2.2, and 1.4 times higher than those of the pure TiO2 nanotubes; and 3.9, 9.3, and 5.6 folds higher than those of the pure Ag2O nanoparticles. It was demonstrated that the improved photocatalytic performances of the nanocomposites were attributed to the hierarchical nanotubular structures that inherited from the natural cellulose substances and the effective heterostructure between the titania and silver oxide phases derived from the unique structure. Hence, the close relationship between the cellulose derived structures and the photocatalytic performances of the nanocomposites were demonstrated. The related possible photocatalytic mechanism was revealed that the separation and transfer of the photogenerated electron–hole pairs was accelerated, and the superoxide radicals and reactive holes played a main role in the photocatalytic processes.