Recent Advances in Nickel-Based Anodes for Anion-Exchange Membrane Water Electrolyzers

Electrochemical water splitting, powered by renewable sources of energy, is proven to be an effective method for producing green hydrogen with high purity. In the class of different types of water-splitting technologies, an anion-exchange membrane water electrolyzer (AEMWE), become a primary alternative to low-cost green hydrogen production. However, electrolysis of water suffers from high overpotential losses because of sluggish oxygen evolution reaction (OER), which heavily impacts the overall performance of AEMWE. Owing to the high cost of benchmark OER catalysts (Ir/Ru-based oxides), platinum group metal (PGM)-free, especially nickel-based catalysts, are considered a potential low-cost catalyst. To scale up this technology, it is necessary to develop catalysts with low overpotential, high stability, and low production cost. This review summarizes recent developments and advancements in Ni-based OER catalysts, OER mechanisms, and their performance and stability both at the electrode and device levels. The quantification of AEMWE performance losses, membrane electrode assembly fabrication methods, single cell and stack level performance is discussed to remark the achievements. We comprehensively compared and analyzed the AEMWE performance and durability achieved using (i) Ni-based anode and PGM cathode, and (ii) Ni-based anode and PGM-free cathode and highlighted the research gap between laboratory-level and actual practical devices. Finally, it summarizes the potential challenges and the opportunities to improve the AEMWE technology beyond laboratories.