Low-Temperature Synthesis of NiO Structures: Tailoring Morphology for Enhanced Dielectric Performance

Nickel oxide (NiO) is a widely studied material for energy storage applications due to its excellent structural and functional properties. This study explores the effect of synthesis pH on the structural, optical, and dielectric properties of NiO nanoparticles to optimize their performance. NiO was synthesized via a hydrothermal method at pH 8 and 12, followed by calcination at 200 °C. At pH 12, X-ray diffraction confirmed the phase transition from β -Ni(OH)₂ to NiO, while TEM analysis revealed the formation of a one-dimensional (1D) structure. Optical studies using UV-visible spectroscopy and photoluminescence revealed defect states that contribute to improved energy storage performance. Dielectric studies revealed superior performance at pH 12. Electrochemical cyclic voltammetry confirmed the enhanced stability and energy storage capabilities of NiO with 1D structure. These findings establish NiO synthesized at pH 12 as a promising candidate for advanced energy storage technologies.