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.