Self-assembly of (NH4)0.3TiO1.1F2.1 crystal by dinitrogen fixation as a precursor of N-doped TiO2 nanosheets

Semiconductor TiO₂ has been always extensively studied for maximizing its environmental- and energy-related applications with tailored facets or doped crystal structure, especially for photocatalysis, solar cell devices, sensors, catalyst supports, and supercapacitor. In this study, in air or argon atmosphere, a novel facile and effective method has been successfully exploited to prepare N-doped TiO₂ nanosheets (air-TiO₂ and Ar-TiO₂) by annealing treatment of non-stoichiometric ammonium oxofluorotitanates crystal ((NH₄)_0.3TiO_1.1F_2.1) with layer-by-layer self-assembled morphology, which is obtained based on the dinitrogen fixation of TiCl₄ in the presence of hydrogen fluoride under mild condition. In this method, the conversion of dinitrogen to ammonium salt has been demonstrated by means of isotopic labeling experiments with labeled ¹⁵N₂ gas acting as benign oxidant and isopropanol as suitable reductant. The resultant of N-doped TiO₂ nanosheets exhibits an enhancement of photocatalytic activity by degrading RhB under visible-light irradiation. In addition, the as-prepared Ar-TiO₂ of N-doped TiO₂ nanosheets obtained from Ar atmosphere also shows a higher electrochemical performance compared with reported pure TiO₂ in the application of supercapacitor. In this study, in air or argon atmosphere, a novel facile and effective method has been successfully exploited to prepare N-doped TiO₂ nanosheets (air-TiO₂ and Ar-TiO₂) by annealing treatment of non-stoichiometric ammonium oxofluorotitanates crystal ((NH₄)_0.3TiO_1.1F_2.1) with layer-by-layer self-assembled morphology, which is obtained based on the dinitrogen fixation of TiCl₄ in the presence of hydrogen fluoride under mild condition.