N-doped Na2Ti6O13@TiO2 core-shell nanobelts with exposed {101} anatase facets and enhanced visible light photocatalytic performance

摘要

N-doped Na2Ti6O13@TiO2 core-shell nanobelts have been successfully synthesized by first mixing Na2Ti3O7 with titanium isopropoxide, and then calcinating with urea in air. A structural evolution from the phase Na2Ti3O7 to Na2Ti6O13 occurred as the TiO6 octahedra in Na2Ti6O13 is more regular. Anatase TiO2 nanoparticles (NPs) with specifically exposed {1 0 1} facets were deposited on the external surface of Na2Ti6O13 nanobelts, forming the closely contacted interface between two components due to the common structural features of TiO6 octahedra in anatase TiO2 and Na2Ti6O13. The reductive {1 0 1} facets could be acted as a possible reservoir of the photogenerated electrons, yielding a highly reactive surface for the reduction of O-2-O-2 center dot- and thus, lowering the recombination rate of photogenerated electron-hole pairs. The anisotropically shaped titanate nanobelts in the obtained composites possessed a higher charge carrier mobility and provided the pathway for quick transport of charge carriers throughout the longitudinal direction to different reaction sites for subsequent reactions. The doped N atoms were mainly located in the crystal lattices of TiO2, giving rise to the visible light response. Owing to the combined effects of hybridization, morphology engineering, and N doping, the obtained composite showed a high stability and an enhanced catalytic activity for the photodegradation of methylene blue (MB) solution under visible light irradiation. In addition, it was found that both an appropriate mass ratio of TiO2 to titanate and a suitable content of doped N were essential for achieving an excellent performance. The present work may provide an insight for the fabrication of delicate composite photocatalysts with a high performance. (C) 2015 Elsevier B.V. All rights reserved.