One-step electrodeposition synthesis of composites of NiFeMn alloy and its hydroxide as an efficient bifunctional water splitting catalyst

The rational design and synthesis of an efficient, durable, and inexpensive water splitting catalyst is essential for industrial electrochemical hydrogen production. In this paper, a composite catalyst of NiFeMn alloy and its hydroxide (NiFeMn/NM) has been grown in situ on a nickel mesh (NM) by a facile one-step electrodeposition method, which has hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) overpotentials of just 54 mV and 241 mV at 10 mA cm⁻² in 1.0 M KOH, respectively. Considering the actual production conditions, the NiFeMn/NM electrode is utilized as the cathode and anode in an electrolyzer with 6.0 M KOH electrolyte, it achieves a current density of up to 1145 mA cm⁻² at 90 °C at a cell voltage of 2.0 V, and shows no significant increase over 200 h under a constant current of 500 mA cm⁻². This study provides a reference value for the preparation of low-cost and high-activity bifunctional electrocatalysts.