Self-Assembled Interwoven Nanohierarchitectures of NaNbO and NaNb Ta O (0.05 ≤ ≤ 0.20): Synthesis, Structural Characterization, Photocatalytic Applications, and Dielectric Properties.

Dependence on fossil fuels for energy purposes leads to the global energy crises due to the nonrenewable nature and high CO production for environmental pollution. Therefore, new ways of nanocatalysis for environmental remediation and sustainable energy resources are being explored. Herein, we report a facile surfactant free, low temperature, and environmentally benign hydrothermal route for development of pure and (5, 10, 15, and 20 mol %) Ta-doped horizontally and vertically interwoven NaNbO nanohierarchitecture photocatalysts. To the best of our knowledge, such a type of hierarchical structure of NaNbO has never been reported before, and changes in the microstructure of these nanoarchitectures on Ta-doping has also been examined for the first time. As-synthesized nanostructures were characterized by different techniques including X-ray diffraction analysis, electron microscopic studies, X-ray photoelectron spectroscopic studies, etc. Ta-doping considerably affects the microstructure of the nanohierarchitectures of NaNbO, which was analyzed by FESEM analysis. The UV-visible diffused reflectance spectroscopy study shows considerable change in the band gap of as-synthesized nanostructures and was found to be ranging from 2.8 to 3.5 eV in pure and different mole % Ta-doped NaNbO. With an increase in dopant concentration, the surface area increases and was equal to 5.8, 6.8, 7.0, 9.2, and 9.7 m/g for pure and 5, 10, 15, and 20 mol % Ta-doped NaNbO, respectively. Photocatalytic activity toward the degradation of methylene blue dye and H evolution reaction shows the highest activity (89% dye removal and 21.4 mmol g catalyst H evolution) for the 10 mol % NaNbO nanostructure which was attributed to a change in the conduction band maximum of the material. At 100 °C and 500 kHz, the dielectric constants of pure and 5, 10, 15, and 20 mol % Ta-doped NaNbO were found to be 111, 510, 491, 488, and 187, respectively. The current study provides the rational insight into the design of nanohierarchitectures and how microstructure affects different properties of the material upon doping.