Mohammed Ismael
Hydrogen is a compelling alternative to fossil fuels because it's clean, has zero emissions, and boasts a high energy output. Renewable energy can be used to achieve large-scale green hydrogen production via proton exchange membrane water electrolyzers (PEMWEs). As a key component of PEMWE cells, porous transport layers (PTLs) play a critical role in enhancing cell performance. The PTLs are responsible for transporting hydrogen on the cathode side as well as water and oxygen on the anode side. In PEMWE cells, passivation of the Ti-based PTLs is a critical issue because it dramatically raises surface contact resistance. Thus, for long-time operations, PTLs are frequently coated with substantial quantities of platinum group metals such as platinum, gold, or iridium to achieve adequate performance profiles. In the present review, the degradation of PTLs in PEMWE was interpreted. Then, we discussed the role of noble metals coated Ti-based PTL in enhancing the performance and durability of PEMWE cells. Other rationally modified PTL methods, like non-noble metal coating, microporous layer, chemical etching, and others were also discussed. This review will contribute to future research advancements and provide a roadmap to assist in the development of the PEM water electrolyzers to produce commercially viable hydrogen.