Two closed-loop nickel-based catalysts for use in alkaline water electrolysis under industrial conditions

This paper presents the preparation and performance evaluation of two closed-loop nickel-based catalysts. The (hydro)oxide coatings of nickel-molybdenum and nickel-iron were electrodeposited onto industrial nickel meshes, which were subsequently used as the cathode and anode (NiMo@NM and NiFe@NM) in alkaline water electrolysis. Both catalysts formed a fully closed-loop configuration, surrounding each nickel wire on the nickel mesh, thereby enhancing the bonding strength with the substrate. The NiMo@NM||NiFe@NM assembly achieved a current density of 200 mA cm⁻² at a cell voltage of only 1.91 V and room temperature, maintaining this level of performance for over 280 h. A single-stack flow cell was used to examine the changes in cell voltage in relation to temperature, current density, and electrolyte flow rate and concentration. The specific energy consumption for hydrogen production can be reduced to 4.1 kWh Nm⁻³ (H₂) under near-industrial conditions (70 °C, 6 M KOH, 400 mA cm⁻²). We hope that this study can help bridge the gap between catalyst studies and practical industrial applications.