Effect of Reduced Graphene Oxide on the Ta₂O₅-IrO₂ Electrocatalyst for Water Splitting

There is a great interest in the development of advanced electrocatalysts for efficient water splitting. A tantalum iridium oxide (Ta₂O₅-IrO₂) coating is considered to be one of the best electrocatalysts for the oxygen evolution reaction (OER) in acidic media. In the present study, novel Ta₂O₅-IrO₂-rGO coatings with varying loads of reduced graphene oxide (rGO) were designed to investigate the effects of rGO on the catalytic activity and stability of the Ta₂O₅-IrO₂ coating for the OER. Five different electrodes comprised of Ta₂O₅-IrO₂-rGO on a titanium substrate were fabricated with incremental weight percentages of rGO (0.0 wt.%, 1.0 wt.%, 2.0 wt.%, 5.0 wt.% and 7.5 wt.%) using a facile thermal decomposition method. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDS) were employed to characterize the morphology and composition of the prepared Ta₂O₅-IrO₂-rGO coatings. Longevity tests revealed that the incorporation of rGO into the oxide layer strongly affected the stability of the Ta₂O₅-IrO₂-rGO electrodes. The electrochemical activities of the prepared Ta₂O₅-IrO₂-rGO electrodes were characterized by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). The Ta₂O₅-IrO₂-rGO coating containing 1.0 wt.% rGO exhibited the greatest stability, along with enhanced OER activity.