Controlled doping of ultralow amounts Ru on Ni cathode for PEMWE: Experimental and theoretical elucidation of enhanced performance

Proton exchange membrane water electrolysis (PEMWE) is an environmentally benign technology for large-scale hydrogen production. Despite many catalysts being developed to replace Pt, successful development of low-cost catalysts that meet the balance of performance and durability is limited. In this work, atomically dispersed Ru on Ni catalyst-integrated porous transport electrodes were fabricated by a simple electrodeposition. With a trace amount of Ru (< 0.05 mg_Ru·cm⁻²), the Ni_98.1Ru_1.9 cathode catalyst exhibited an overpotential of 35 mV at –10 mA·cm⁻² with excellent stability. Density functional theory calculation revealed that the high performance was driven by optimized adsorption strength and improved mobility of hydrogen on the catalyst surface. The Ni_98.1Ru_1.9 electrode was further verified in a PEMWE cell and resulting performance (6.0 A·cm⁻² at 2.25 V_cell) and stability (0.13 mV·h⁻¹ decay rate at 1 A·cm⁻²) surpassed previously reported non-Pt and even Pt electrodes, demonstrating its readiness as an advanced cathode to replace Pt.