Structural and Electrochemical Insights into Ultrasonic Spray Pyrolysis‐Derived Pure and Zn‐Modified Mn ₃ O ₄ for High‐Performance Supercapacitors

In this study, Mn ₃ O ₄ and Zn‐modified Mn ₃ O ₄ thin films are synthesized on glass substrates using ultrasonic spray pyrolysis. A comprehensive analysis is performed on their structural, optical, chemical, photoluminescent, and electrochemical properties. X‐ray diffraction confirmed the formation of a tetragonal hausmannite phase, with peak shifts indicating lattice distortion due to Zn incorporation. Ultraviolet–Visible (UV–Vis) analysis showed a band gap increase from 2.00 to 2.51 eV with Zn doping, alongside reduced visible‐region absorbance. X‐ray photoelectron spectroscopy validated the substitution of Zn ²⁺ ions and provided insight into the Mn and Zn oxidation states. Photoluminescence spectra indicated reduced radiative recombination upon doping. Electrochemical evaluations using galvanostatic charge–discharge, electrochemical impedance spectroscopy, and cyclic voltammetry demonstrated significant improvement in charge storage for Zn‐doped electrodes. Capacitance values increased from 25 F g ⁻¹ (pure) to 93 F g ⁻¹ (Zn‐doped) at 10 mV s ⁻¹ , with a maximum value of 333 F g ⁻¹ observed for 2% Zn‐doped Mn ₃ O ₄ at 1 A g ⁻¹ . The Zn additive enhanced both the charge transport and capacitive behavior, affirming its promise for energy‐storage applications.