“…To date, catalysts derived from the noble metal iridium (Ir), along with their corresponding metal oxides, have demonstrated the capability to fulfill the necessary criteria for the practical implementation of PEMWE. − The scarcity and relatively low intrinsic activity impede Ir-based catalysts for industrial-scale hydrogen (H 2 ) production. − In contrast, ruthenium-based catalysts (particularly RuO 2 ) offer lower costs and higher activity, making them more promising for catalyzing the OER. However, the excessive oxidation of ruthenium leads to the production of highly soluble Ru species (Ru n + , n > 4), which accelerates catalyst degradation and significantly reduces electrochemical efficiency. − The insufficient durability of these catalysts remains a critical obstacle in their utilization. , Thus far, numerous strategies, such as metal doping, − engineered nanostructures, − and fabricating heterostructures, − have been proposed to enhance the activity and stability of RuO 2 .…”