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Metal oxides of earth‐abundant elements are promising electrocatalysts to overcome the sluggish oxygen evolution and oxygen reduction reaction (OER/ORR) in many electrochemical energy‐conversion devices. However, it is difficult to control their catalytic activity precisely. Here, a general three‐stage synthesis strategy is described to produce a family of hybrid materials comprising amorphous bimetallic oxide nanoparticles anchored on N‐doped reduced graphene oxide with simultaneous control of nanoparticle elemental composition, size, and crystallinity. Amorphous Fe_0.5Co_0.5O_x is obtained from Prussian blue analog nanocrystals, showing excellent OER activity with a Tafel slope of 30.1 mV dec⁻¹ and an overpotential of 257 mV for 10 mA cm⁻² and superior ORR activity with a large limiting current density of −5.25 mA cm⁻² at 0.6 V. A fabricated Zn–air battery delivers a specific capacity of 756 mA h g_Zn …