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

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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)0.3TiO1.1F2.1) 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)0.3TiO1.1F2.1) 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.