Electrochemical Growth Optimization of IrOx Films on Stainless Steel as Electrodes for High Performance Supercapacitors

Iridium oxide (IrOx) films were electrochemically deposited using cyclic voltammetry, varying the number of cycles and the scan rates to analyze their role in the electrochemical performance of the modified electrodes. The number of cycles was varied as 20, 40, 60 and 80 cycles, and the scan rates were varied as 25, 36, 42 and 50 mVs^-1. The SEM analysis showed that initially there is the formation of a homogenous layer of small iridium oxide nuclei and, as the films grow thicker, the nuclei start to merge and form nuclei with larger diameters. The electrochemical characterization was carried out in a three-electrode setup using 1M Na₂SO₄ with a potential window of 1.2 V vs SCE. The highest specific capacitance was approximately 445 Fg^-1, obtained by a sample synthesized at a scan rate of 50 mVs^-1 with 40 cycles. The same sample exhibited a capacitance retention of 98.15 % after 5000 cycles at 50 Ag^-1. Moreover, it also displayed a 91.2 % capacitance retention after 50,000 cycles at 50 Ag^-1. These results show the potential use of this material for supercapacitor applications where reliability and safety are key parameters rather than investment costs.