Recent advances in nickel-based anodes for anion-exchange membrane water electrolyzers

Abstract

Electrochemical water splitting, powered by renewable sources of energy, has proven to be an effective method for producing green hydrogen with high purity. Among the different types of water-splitting technologies, anion-exchange membrane water electrolyzers (AEMWEs) have become primary alternatives for low-cost green hydrogen production. However, electrolysis of water suffers from high overpotential losses because of the sluggish oxygen evolution reaction (OER), which heavily impacts the overall performance of AEMWEs. Owing to the high cost of benchmark OER catalysts (Ir/Ru-based oxides), platinum group metal (PGM)-free catalysts, especially nickel-based catalysts, are considered potential low-cost alternatives. 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 at both the electrode and device levels. The quantification of AEMWE performance losses and single-cell and stack-level performance, along with the analysis of membrane electrode assembly fabrication methods, is discussed. We comprehensively compared and analyzed the AEMWE performance and durability achieved using (i) Ni-based anodes and PGM cathodes, and (ii) Ni-based anodes and PGM-free cathodes and highlighted the research gap between laboratory-level and practical devices. Finally, it summarizes the potential challenges and opportunities to improve the AEMWE technology beyond laboratories.