Review—Reference Electrodes in Proton Exchange Membrane Water Electrolysis: Previous Approaches, Current Application, and Perspectives

The commercialization of proton exchange membrane water electrolysis cells (PEMWEs), which are essential for a greener and more sustainable future, is hindered by the high costs of noble metal catalysts, as well as the degradation of the catalysts and membranes. Examining the electrodes’ characteristics with reference electrodes (REs) yields insights into their individual performance and can, e.g., help assess new catalyst layer designs, their interplay with the adjacent porous transport layer, or understand the complex and multi-faceted degradation mechanisms. This review provides an overview of previous approaches and the evolution of RE designs in PEMWE. By discussing the strengths and limitations of different RE setups, readers are enabled to make more informed decisions about their experiments’ design and choose the best RE setup for their specific research question.