Improved Electrocatalytic Performance in Overall Water Splitting with Rational Design of Hierarchical Co3O4@NiFe Layered Double Hydroxide Core‐Shell Nanostructure.

Abstract: The development of low‐cost and highly reactive electrocatalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in basic media is still a great challenge. Herein, we design a three‐dimensional Co₃O₄@NiFe‐LDH (LDH: layered double hydroxide) core‐shell nanostructure on Ni foam, in which the core Co₃O₄ nanowires play a key role in the stability and the shell NiFe‐LDH nanosheets provide the main active sites for electrocatalytic water splitting. The as‐prepared Co₃O₄@NiFe‐LDH exhibits excellent electrocatalytic activity for OER with a low overpotential of 269 mV at a current density of 100 mA cm⁻², a small Tafel slope of 66 mV dec⁻¹, and excellent stability without degradation over 40 h. Furthermore, the sample also demonstrates robust performance for HER with a low overpotential of 74 mV at a current density of 10 mA cm⁻². Most importantly, when employing the Co₃O₄@NiFe‐LDH/NF as both anode and cathode, only 1.56 V is needed to achieve a current density of 10 mA cm⁻², which is lower than the combination of Pt/C and IrO₂ catalysts for overall water splitting. This work provides a significant strategy toward the rational design of novel core‐shell electrocatalysts for overall water splitting. [ABSTRACT FROM AUTHOR]