Restructured Co‐Ru alloys via electrodeposition for efficient hydrogen production in proton exchange membrane water electrolyzers

The design of robust and high-performance hydrogen evolution reaction (HER) catalysts is crucial for the scalable production of hydrogen by electrochemical water splitting. In this work, we fabricated hierarchically porous Co-Ru catalysts with excellent catalytic activity and durability in acidic media. The morphology of the Co-Ru catalysts was successfully controlled through an optimized electrochemical process. Among all Co-Ru samples prepared in this study, the Co72Ru28 catalyst exhibited the largest catalytic surface area, as well as excellent HER activity (overpotential of 26.4 mV at −10 mA cm−2) and durability. X-ray photoelectron spectroscopy measurements revealed the electron transfer between Co and Ru, indicating that the formation of the Co-Ru alloy improved the activity and durability of the catalyst. Furthermore, a proton exchange membrane water electrolyzer (PEMWE) prepared with the Co72Ru28 sample showed excellent performances (3.4 A cm−2 at 2.0 Vcell), illustrating the promising potential of the present Co-Ru catalysts as cathode materials for PEMWE systems.