Unveiling the Enhancement of Electrocatalytic Oxygen Evolution Activity in Ru-Fe₂O₃/CoS Heterojunction Catalysts

The development of highly efficient electrocatalysts for the sluggish anodic oxygen evolution reaction (OER) is crucial to meet the practical demand for water splitting. In this study, an effective approach is proposed that simultaneously enhances interfacial interaction and catalytic activity by modifying Fe₂O₃/CoS heterojunction using Ru doping strategy to construct an efficient electrocatalytic oxygen evolution catalyst. The unique morphology of Ru doped Fe₂O₃ (Ru-Fe₂O₃) nanoring decorated by CoS nanoparticles ensures a large active surface area and a high number of active sites. The designed Ru-Fe₂O₃/CoS catalyst achieves a low OER overpotential (264 mV) at 10 mA cm^-2 and demonstrates exceptional stability even at high current density of 100 mA cm^-2, maintaining its performance for an impressive duration of 90 h. The catalytic performance of this Ru-Fe₂O₃/CoS catalyst surpasses that of other iron-based oxide catalysts and even outperforms the state-of-the-art RuO₂. Density functional theory (DFT) calculation as well as experimental in situ characterization confirm that the introduction of Ru atoms can enhance the interfacial electron interaction, accelerating the electron transfer, and serve as highly active sites reducing the energy barrier for rate determination step. This work provides an efficient strategy to reveal the enhancement of electrocatalytic oxygen evolution activity of heterojunction catalysts by doping engineering.