Hierarchical Fe Doped Co Oxide/Hydroxide Nanosheet Arrays as Highly Efficient Oxygen Evolution Catalysts Prepared by Hydrothermal Etching of FeCo Prussian Blue Analogue

Earth-abundant metal oxides/hydroxides have recently been identified as promising catalysts for oxygen evolution reaction (OER) in alkaline media, while the overall efficiency is still limited by the sluggish kinetics. Therefore, searching for facile and effective method to prepare composition and morphology tunable catalyst, as well as understanding its reactivity are urgent tasks. Here, we report a hydrothermal etching strategy for the synthesis of Fe doped Co oxides/hydroxide hybrid catalyst with hierarchical nanosheet array architecture. The as-obtained catalyst shows an overpotential of 219 mV without iR compensation at 10 mA/cm(2) and a low Tafel slope of 46.4 mV/dec, surpassing the other control catalysts in this work and most similar catalysts in literature. Comprehensive studies confirm that both composition and morphology can be rationally tuned by adjusting the hydrothermal etching parameters, and the improvement of activity is attributed to the highly active Fe doped Co oxides/hydroxide species together with the unique 3D hierarchical structure.