Template-Free Synthesis of Core-Shell TiO2 Microspheres Covered with High-Energy {116}-Facet-Exposed N-Doped Nanosheets and Enhanced Photocatalytic Activity under Visible Light

• Published in: Chemistry : a European journal 2014-12, Vol.20 (51), p.17039-17046
• Main Authors: Chen, Qifeng, Ren, Baosheng, Zhao, Yubao, Xu, Xun, Ge, Heyi, Guan, Ruifang, Zhao, Jincai
• Format: Article
• Language: English
• Subjects: Chemistry; core-shell structures; high-energy facets; Photocatalysis; self-assembly; Shells; titanium dioxide
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201404816

Core–shell TiO2 microspheres possess a unique structure and interesting properties, and therefore, they have received much attention. The high‐energy facets of TiO2 also are being widely studied for the high photocatalytic activities they are associated with. However, the synthesis of the core–shell structure is difficult to achieve and requires multiple‐steps and/or is expensive. Hydrofluoric acid (HF), which is highly corrosive, is usually used in the controlling high‐energy facet production. Therefore, it is still a significant challenge to develop low‐temperature, template‐free, shape‐controlled, and relative green self‐assembly routes for the formation of core–shell‐structured TiO2 microspheres with high‐energy facets. Here, we report a template‐ and hydrofluoric acid free solvothermal self‐assembly approach to synthesize core–shell TiO2 microspheres covered with high‐energy {116}‐facet‐exposed nanosheets, an approach in which 1,4‐butanediamine plays a key role in the formation of nanosheets with exposed {116} facets and the doping of nitrogen in situ. In the structure, nanoparticle aggregates and nanosheets with {116} high‐energy facets exposed act as core and shell, respectively. The photocatalytic activity for degradation of 2,4,6‐tribromophenol and Rhodamine B under visible irradiation and UV/Vis irradiation has been examined, and improved photocatalytic activity under visible light owing to the hierarchical core–shell structure, {116}‐plane‐oriented nanosheets, in situ N doping, and large surface areas has been found. Core–shell TiO2 covered with high‐energy {116}‐plane‐oriented nanosheets was synthesized by a facile one‐step solvothermal reaction followed by calcination. Small organic molecules, such as 1,4‐butanediamine, played an important role in the formation of nanosheets with the {116} facets exposed and in the doping of nitrogen into interstitial positions of the TiO2 lattice, which enhanced the photocatalytic activity of the material under visible light.