Abstract and subjects
Anion exchange membrane water electrolyzers (AEMWEs) can generate hydrogen with a pure water feed using noble metal-free catalysts. The development of highly active and stable catalysts for oxygen evolution reaction (OER) is required for improving performance of AEMWEs systems. Ni-Fe (oxy)hydroxides show high OER catalytic activity in alkaline media, but typically have low surface area. In this work, we investigate a series of Ni-Fe oxides with high surface area and disordered morphology, obtained using an aerogel synthesis method. We evaluate the impact of different synthesis variables on the OER activity and demonstrate that heat treatment at high temperatures generates more ordered structure, resulting in a decrease in OER activity. Advanced characterization reveals that maintaining highly disordered and porous structure of the aerogel is essential to achieving high OER activity, as it enables the formation of highly OER-active lamellar structures of the catalyst.
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•Ni-Fe-based aerogels synthesized via sol-gel method and supercritical drying.•High surface area likely a major contributing factor to high OER activity.•Heat treatment has strong impact on catalyst morphology and activity.•High level of structural disorder is essential for high OER activity.•2.0Acm−2 at 1.9 V in AEMWE with 0.1 M KOH..