Advancing layered double hydroxides (LDHs) as the anodes for efficient anion-exchange-membrane water electrolyzers

Abstract

The transition to sustainable energy systems necessitates efficient hydrogen production via water electrolysis, with anion-exchange membrane water electrolyzers (AEMWEs) emerging as a cost-effective alternative by combining the merits of alkaline water electrolyzers (AWEs) and proton-exchange membrane water electrolyzers (PEMWEs). However, challenges persist in membrane stability, oxygen evolution reaction (OER) kinetics, and mass transport efficiency. This review highlights the pivotal role of transition metal-based layered double hydroxides (LDHs) as high-performance, non-precious OER catalysts for AEMWEs, emphasizing their tunable electronic structures, abundant active sites, and alkaline stability. We systematically outline LDHs synthesis strategies (top-down/bottom-up approaches, and self-supporting LDHs engineering on the conductive substrates), and AEMWE component design, including membrane-electrode assembly optimization and ionomer-free architectures. Standardized evaluation protocols-short-circuit inspection, impedance spectroscopy, and durability assessment are detailed to benchmark performance. Moreover, recent advances in LDHs modification (cation/anion doping, heterojunction design, three-dimensional (3D) electrode structuring) are discussed for alkaline-fed systems, alongside emerging applications in seawater and pure-water electrolysis. By correlating material innovations with device-level metrics, this work provides a roadmap to address scalability challenges, offering perspectives on advancing AEMWEs for sustainable, large-scale hydrogen production.