Sol–gel engineered Zr-doped MgO nanostructures: Multifunctional characterization and electrochemical enhancement for energy storage applications

This research focuses on the systematic doping of magnesium oxide with zirconium to evaluate how compositional changes impact its different characteristics and enhance the electrochemical behavior of the sample for charge storage applications. Zirconium-doped magnesium oxide (Zr x Mg 1-x O) was synthesized in three different concentrations(x = 0, 0.015, and 0.0175) by the sol-gel method. Structural characteristics studied from PXRD showed enhancement in crystalline nature with crystallite size reduction from 53.35 nm to 47.84 nm by doping. The morphological analysis showed that the Zr doping enhances the morphology, which indicates a change in crystal growth dynamics. The band gap of the sample was found to be narrowed from 4.164 to 4.098 eV on doping was calculated from the Tauc plot drawn using UV-absorption data. Electrochemical characterization revealed significant improvements upon Zr doping. The 1.75% Zr-doped MgO sample exhibited a stable potential profile in galvanostatic charge–discharge (GCD) analysis, minimal resistance (R= 0.559 Ω), increased double-layer capacitance (admittance, Y 0 =446.5), and broader cyclic voltammetry (CV) loops with higher peak currents, confirming enhanced redox activity and charge storage. These findings demonstrate that sol–gel-engineered Zr-doped MgO nanostructures offer improved conductivity, ion diffusion pathways, and electrochemical robustness, making them suitable for hybrid energy storage applications.