Synergistic coupling of CoFe-LDH arrays with NiFe-LDH nanosheet for highly efficient overall water splitting in alkaline media

Developing active, stable and cost-effective bifunctional electrocatalysts with earth-abundant metals (Ni, Fe, Co) is a prerequisite to achieve overall water splitting. In this work, a novel CoFe-layered double hydroxide (LDH) coupled with NiFe-LDH nanosheet array supported on nickel foam (denoted as CoFe@NiFe/NF) is developed through a facile hydrothermal and electrodeposition method. Remarkably, benefiting from strong synergistic effect between CoFe-LDH and NiFe-LDH and the unique structural features, the resulting CoFe@NiFe/NF architectures catalyst exhibits excellent activities and stabilities for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Furthermore, an efficient and stable alkali-electrolyzer using CoFe@NiFe/NF as both the cathode and anode achieve a voltage of 1.59 V at the current density of 10 mA cm(-2), which is superior to many other state-of-the-art earth-abundant electrocatalysts. This work provides a facile method for enhancing the electrocatalytic activity by constructing hierarchical core-shell architectures using the LDH nanosheet materials.