Ionomer-free Co-Ru based electrode for efficient proton exchange membrane water electrolysis via synergistic catalysis

Proton exchange membrane water electrolysis (PEMWE) is a sustainable method for green hydrogen production. However, its application is hindered by the high cost of the requisite noble-metal-based electrocatalysts such as iridium (Ir). Herein, self-supported Co-Ru-based electrodes are fabricated on titanium (Ti) paper and carbon paper (CP) substrates for a highly efficient PEMWE. The Co-Ru/CP and Co-Ru-O/Ti electrodes exhibit porous surface structures, along with uniform Ru distributions and coupling interfaces formed by Co-and Ru-related metal and oxide components. These features, combined with electronic interactions in the Co-Ru bonds and the suppression of Ru over-oxidation by the Co species, significantly enhance the catalytic activity and stability in 0.5 M H2SO4. These self-supported electrodes achieve low overpotentials of 24.8 mV for the hydrogen evolution reaction and 209 mV for the oxygen evolution reaction at 10 mA cm-2, along with a durability of 70 h. A fabricated two-electrode cell for overall water splitting exhibits a cell voltage of 1.52 V at 10 mA cm-2, with a durability of 20 h. The developed Co-Ru-based PEMWE single-cell demonstrates superior performance (1.5 A cm-2 at 2.0 V) and durability (stable at 0.5 A cm-2 for 75 h), achieving significantly higher catalyst cost efficiency (783 A USD-1) than Ru (195 A USD-1) and commercial catalysts such as Pt and Ir (23 A USD-1) The lowcost, high-performance, and ionomer-free electrode shows strong potential for practical Ru-based water electrolysis in PEMWE.