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

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. Ni‐Co‐Fe hydr(oxy)oxide@Ni‐Co layered double oxide yolk‐shelled microrods (NiCoFe‐HO@NiCo‐LDH YSMRs) are designed as an electrocatalyst for the oxygen evolution reaction (OER) through a two‐step conversion strategy. Owing to the enhanced mass transport of the structure and the modulated chemical environment of metal species, the obtained NiCoFe‐HO@NiCo‐LDH YSMRs demonstrate enhanced electrocatalytic activity for OER with good stability.