Amorphous nickel-iron oxides/carbon nanohybrids for an efficient and durable oxygen evolution reaction

Highly efficient and durable water oxidation electrocatalysts are critically important in a wide range of clean energy technologies, including water electrolyzers and rechargeable metal-air batteries. Here, we report a novel sonochemical approach to synthesize amorphous nickel-iron oxides/carbon nanohybrids with tunable compositions for the oxygen evolution reaction (OER). The sonochemically synthesized amorphous electrocatalysts with optimal composition exhibit a low overpotential of 290 mV at 10 mA·cm^-2 and a Tafel slope of 31 mV·decade^-1 in a 0.1 M KOH electrolyte, outperforming the benchmark RuO₂ catalyst. Meanwhile, these nanohybrids are also highly stable and remain amorphous even after prolonged cycling. In addition to amorphism, sonochemistry endows as-prepared nickel-iron oxides/carbon nanohybrids with a simultaneously formed carbon scaffold and internal Ni(0), which can enhance the stability and activity for the OER. This work demonstrates that sonochemistry is a unique method for synthesizing amorphous metal oxides toward an efficient and durable OER.