Construction of Ni‐Co‐Fe Hydr(oxy)oxide@Ni‐Co Layered Double Hydroxide Yolk‐Shelled Microrods for Enhanced Oxygen Evolution

Abstract The exploration of earth‐abundant and efficient electrocatalysts toward the oxygen evolution reaction (OER) is critical for sustainable energy storage and conversion devices. In this work, we report a self‐engaged strategy to fabricate a yolk‐shelled OER electrocatalyst. Starting with a metal–organic framework, Co‐Fe layered double hydroxide (LDH)@zeolitic imidazolate framework‐67 (ZIF‐67) yolk‐shelled structures are formed in one step. Afterwards, these ZIF‐67 building blocks are transformed into Ni‐Co LDH nanocages to form the Ni‐Co‐Fe hydr(oxy)oxide@Ni‐Co LDH yolk‐shelled microrods (NiCoFe‐HO@NiCo‐LDH YSMRs) through an ion‐exchange reaction. Owing to the structural and compositional merits, the NiCoFe‐HO@NiCo‐LDH YSMR electrocatalyst exhibits an overpotential of 278 mV to reach the current density of 10 mA cm −2 , a small Tafel slope of 49.7 mV dec −1 , and good stability in alkaline media.