Self-Assembled Interwoven Nanohierarchitectures of NaNbO3 and NaNb1- x Ta x O3 (0.05 ≤ x ≤ 0.20): Synthesis, Structural Characterization, Photocatalytic Applications, and Dielectric Properties

Umar Farooq; Jahangeer Ahmed; Saad M Alshehri; Yuanbing Mao; Tokeer Ahmad

doi:10.1021/acsomega.1c07250

Self-Assembled Interwoven Nanohierarchitectures of NaNbO₃ and NaNb_{1- x} Ta _x O₃ (0.05 ≤ x ≤ 0.20): Synthesis, Structural Characterization, Photocatalytic Applications, and Dielectric Properties

ACS Omega. 2022 May 9;7(20):16952-16967. doi: 10.1021/acsomega.1c07250. eCollection 2022 May 24.

Authors

Umar Farooq¹, Jahangeer Ahmed², Saad M Alshehri², Yuanbing Mao³, Tokeer Ahmad¹

Affiliations

¹ Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025, India.
² Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
³ Department of Chemistry, Illinois Institute of Technology, 3105 South Dearborn Street, Chicago, Illinois 60616, United States.

Abstract

Dependence on fossil fuels for energy purposes leads to the global energy crises due to the nonrenewable nature and high CO₂ 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 NaNbO₃ nanohierarchitecture photocatalysts. To the best of our knowledge, such a type of hierarchical structure of NaNbO₃ 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 NaNbO₃, 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 NaNbO₃. 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 m²/g for pure and 5, 10, 15, and 20 mol % Ta-doped NaNbO₃, respectively. Photocatalytic activity toward the degradation of methylene blue dye and H₂ evolution reaction shows the highest activity (89% dye removal and 21.4 mmol g^-1 catalyst H₂ evolution) for the 10 mol % NaNbO₃ 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 NaNbO₃ 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.