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/cm2 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.

The Cover Feature shows the oxygen evolution process catalyzed by a hierarchical FeCo oxide/hydroxide catalyst grown on Ni foam, which is prepared by a hydrothermal etching method with FeCo Prussian blue analogue as precursor. Spectroscopic and microscopic investigation demonstrated that the electronic structure of the surface was optimized by Fe doping, and more active sites were exposed with a self‐standing 2D/2D hierarchical structure. The harmony of these two aspects contributes greatly to the outstanding OER catalytic activity. More information can be found in the Research Article by R. Xiang and co‐workers.