Supercapacitive Performance of SILAR Grown Mn₃O₄ Nanoclusters: Effect of Cationic Precursor Concentration

Herein, we have investigated the effect of cationic precursor (manganese chloride tetrahydrate) concentration on the electrochemical performance of successive ionic layer adsorption and reaction (SILAR)-deposited Mn₃O₄ thin films. The concentration of the cationic precursor was varied from 0.05 to 0.15 M, and its effect on physicochemical and electrochemical properties was studied. X-ray diffraction and X-ray photoelectron spectroscopy analyses confirmed that Mn₃O₄ has a tetragonal structure with Mn²⁺ and Mn³⁺ oxidation states. SEM micrographs revealed that nanoclusters of Mn₃O₄ with an average size of ~200 nm were formed. Moreover, transmission electron microscopy analysis revealed that these nanoclusters were formed from tiny square nanoplates with a size of ~40 nm. Electrochemical studies of the synthesized Mn₃O₄ thin films were recorded in a three-electrode system, which suggests that 0.1 M cationic precursor concentration has a good electrochemical signature with a specific capacitance of 470 F/g at 1 mA/cm² current density in 1 M Na₂SO₄ aqueous electrolyte. The cyclic stability offered was appreciable, with capacitive retention of 75% up to 10,000 CV cycles scanned at 100 mV/s. The charge storage kinetics of the SILAR-grown Mn₃O₄ thin film were investigated. With systematic study we concluded that, the molarity of the cationic precursor plays a vital role in the porosity and microstructure which drastically affects the electrochemical performance.