CuMn2O4 spinel electrodes: effect of the hydrothermal treatment duration on electrochemical performance

CuMn₂O₄ (CMO) thin films are produced using a simple hydrothermal method. The influence of reaction duration on the electrodes’ electrochemical performance is investigated. XRD data shows improved crystal structure after 24-h reaction time, with a crystallite size of 12.17 nm. Distinct vibrational peaks associated with Cu–O and Mn–O are observed in the ATR-FTIR spectra, corroborating the spinel formation after 24 h. XPS analysis shows a compositional shift over time, starting with copper hydroxide at 12 h, evolving into a mix of copper and manganese oxides, hydroxides, and oxyhydroxides by 18 h, and achieving the desired spinel composition by 24 h. Microscopic analysis reveals CMO is arranged as small sheet structures, with 4.95 ± 2.92 µm in length after 24-h reaction. The CMO_24h electrode displays a maximum specific capacitance of 1187.50 Fg⁻¹ at a scan rate of 1 mVs⁻¹ in 1 M Na₂SO₄ electrolyte. The electrochemical performance of the synthesized CMO electrodes reveals a high potential for energy storage applications.