High-conductivity NiFe@Ni@Cu composite electrodes for durable and efficient industrial oxygen evolution

Abstract

The oxygen evolution reaction (OER) is a key bottleneck in water electrolysis due to its sluggish kinetics. Although nickel–iron layered double hydroxides (NiFe LDHs) are promising OER catalysts in alkaline media, their low electrical conductivity hinders industrial-scale applications. Copper mesh substrates offer excellent conductivity and low cost but suffer from poor corrosion resistance, limiting their use as electrode supports. Herein, we report a self-supported NiFe@Ni@Cu composite electrode, fabricated by sequential electrodeposition of a nickel interlayer and Ni₃Fe alloy–NiFe LDH hybrid nanosheets onto a copper mesh. This hierarchical structure synergistically combines the high conductivity of copper and the corrosion resistance of the nickel interlayer, leading to a substantial enhancement in OER activity and stability. The electrode shows a low overpotential of 283 mV at 100 mA cm⁻² and a Tafel slope of 33.4 mV dec⁻¹ in 1 M KOH. As a full water-splitting electrocatalyst, it operates stably at 500 mA cm⁻², with a 23.3% reduction in cell voltage compared to NiFe@Ni, and demonstrates outstanding durability under industrial conditions (30 wt% KOH, 80 °C) for over 80 hours. Moreover, coupled with a NiFe@Ni@Cu cathode, the integrated electrolyzer delivers 100 mA cm⁻² at 1.53 V. This substrate engineering strategy offers a scalable and cost-effective approach to efficient and durable alkaline water electrolysis.