Alkaline electrolyte membrane electrolyzers are a promising technology to efficiently produce clean hydrogen without the use of critical raw materials. At the heart of these electrolyzers are the electrocatalysts, which facilitate the cathodic and anodic reactions, with the latter oxygen evolution reaction (OER) being the most sluggish. In recent years, aerogels have become a very well-studied class of materials due to their unique properties, including very high surface area. Until now, aerogels have not been used to catalyze the OER by themselves but were mainly considered catalyst supports. Here, mixed-metal nickel-iron oxide aerogels were synthesized with a modified epoxide route synthesis and tested as OER catalysts. Depending on the Ni/Fe ratio, they show very high catalytic activity and low overpotential to reach 10 mA cm-2(at η = 380 mV). This activity is beyond that of the existing state-of-the-art platinum group metal-free OER catalysts.
Bibliographical noteFunding Information:
The authors would like to thank the Israeli Ministry of Energy for funding this project. This work was conducted in the framework of the Israeli Fuel Cells Consortium. STEM research was conducted as part of a user project at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory.
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- PGM-free catalysts
- alkaline electrolyte membrane electrolyzers
- mixed-metal oxides
- oxygen evolution reaction