The use of silica in IrO2-based DSA type electrode: An efficient approach to construct cost-effective, potent electrodes for oxygen evolution reaction

Two types of coating, coatings, i.e. IrO₂–Ta₂O₅/Ti and IrO₂–Ta₂O₅–SiO₂/Ti were fabricated by the sol-gel method to investigate the effect of silica on the electrode characteristics. The characterization of the coatings was performed by the scanning electron microscope (SEM), energy dispersive X-ray spectroscopy mapping (EDS), and X-ray diffraction (XRD). The analysis of surface morphology indicated that the presence of SiO₂ in the coatings decreased the size of cracks, where the minimum crack size was observed for the coating containing 35% of SiO₂. The catalytic activities of the prepared electrodes to conduct the oxygen evolution reaction were evaluated in 0.5 M H₂SO₄ solution by electrochemical measurements including cycling voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrodes constructed were named hereafter as IT-0, ITS-35, and ITS-55 with the compositions of IrO₂ (70%)-Ta₂O₅ (30%)/Ti, IrO₂ (35%)-Ta₂O₅ (30%)-SiO₂ (35%)/Ti and IrO₂ (15%)-Ta₂O₅ (30%)-SiO₂ (55%)/Ti, respectively. The accelerated lifetimes measured for the IT-0, ITS-35, and ITS-55 electrodes were obtained as 210, 230, and 173 h, respectively. Such a result was remarkable from the point of view that the optimization of SiO₂ quantity in the coating composition not only decreased the content of IrO₂ but also improved the stability of the electrode. Furthermore, the resulted electrode (ITS-35) exhibited no significant reduction in its catalytic activity when compared to the electrode with a higher amount of IrO₂ (IT-0). Due to the high service lifetime of prepared electrodes, these electrodes are good candidates for OER processes such as electrowinning.