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.