FeNi-Based Aerogels Containing FeNi3 Nanoclusters Embedded with a Crystalline–Amorphous Heterojunction as High-Efficiency Oxygen Evolution Catalysts

In green hydrogen production via water electrolysis, catalysts with multiscale nanostructures synthesized by compositing micro-heterojunctions and nanoporous structures exhibit excellent electrocatalytic oxygen evolution reaction (OER) performance. Moreover, they are the most promising non-noble metal catalysts. Herein, FeNi-based aerogels with a three-dimensional nanoporous structure and amorphous matrix embedded with FeNi₃ nanoclusters were synthesized via wet chemical reduction coprecipitation. The FeNi₃ nanoclusters and the FeNi-based amorphous matrix formed a crystalline-amorphous heterojunction. These aerogels exhibited excellent OER performance and electrocatalytic stability in alkaline electrolytes. In 1 mol/L of KOH electrolyte, the as-synthesized aerogel exhibited an overpotential of 262 mV at a current density of 20 mA cm^-2 with a Tafel slope of only 46 mV dec^-1. It also demonstrated excellent stability during a 12 h chronopotentiometry test.