Coupling Joule Heating with Vibration Ball Milling for Synthesizing Carbon-Supported Ni_{100–<i>x</i>}Fe_<i>x</i> Nanoparticles Achieving Efficient Oxygen Evolution and Alkaline Water Electrolysis

Rapid and cost-effective synthesis of electrocatalysts for oxygen evolution reaction (OER) poses a significant technical challenge for the commercialization of water electrolysis. We, herein, report a facile strategy that couples quick Joule heating with mechanical ball milling for synthesizing well-defined Ni100–xFex (0 ≤ x ≤ 100) alloy nanoparticles on carbon substrate toward high-efficiency OER and water splitting. This synthetic strategy involves first simply mixing the precursors and carbon substrate through ball milling and subsequent Joule heating on an electrical device for fast forming carbon-supported alloy nanoparticles with fine sizes and uniform distribution. In particular, the single-component Ni/C nanoparticles (i.e., x = 0) synthesized by this way include both fcc and hcp crystal phases, with the highest proportion of hcp phase at 370 °C, which endows the Ni/C nanoparticles with better OER activity than that of Ni/C samples synthesized at other temperatures. In addition, the Ni100–xFex/C nanoparticles at an appropriate Ni/Fe ratio of 72/28 (Ni72Fe28/C) exhibit the best OER electrocatalysis, with a low overpotential of only 276 mV at a current density of 10 mA cm–2, due to the optimal electronic interaction between Ni and Fe in the alloys. More importantly, under simulated industrial electrolysis conditions (30 wt % KOH at 60 °C), a two-electrode alkaline electrolyzer assembled with Ni72Fe28/C at the anode and commercial Pt/C at the cathode (Ni72Fe28/C||Pt/C) requires only 1.39 V to deliver the current density of 100 mA cm–2, along with an excellent 120-h durability at the same current density.