Preparation of Co(OH)2@NiFe/NF bifunctional electrocatalyst by electrodeposition for efficient water splitting

The use of earth-abundant metals such as nickel, iron and cobalt is an effective strategy to develop active bifunctional electrocatalysts for water splitting. Herein, a novel binder-free nickel foam (NF) supported Co(OH)2 composite on NiFe electrocatalyst (denoted as Co(OH)2@NiFe/NF) is developed using simple two-step electrodeposition. The unique structure of Co(OH)2 nanoflowers grown on NiFe nanosheets is observed by SEM. The prepared catalyst has high activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The overpotential of HER is 87 mV and that of OER is only 191 mV with current density of 10 mA cm−2 in 1 M KOH. In addition, Co(OH)2@NiFe/NF is used as anode and cathode, which requires only 1.52 V to reach current density of 10 mA cm−2 and 60 h stability, superior to many other advanced electrocatalysts. This provides a new way to prepare low-cost, high-performance and stable electrochemical water electrolysis electrocatalyst.