Dynamic Confinement via Core‐Shell Built‐In Electric Field Achieves Sustainable High‐Current PEMWE

Abstract Developing efficient and durable bifunctional electrocatalysts for the acidic oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is crucial for cost‐effective green hydrogen production. Although ruthenium (Ru) is widely recognized as a low‐cost alternative to iridium, their practical application is hindered by sluggish kinetics and dissolution. To address these limitations, a dynamic confinement strategy is developed through a novel core‐shell built‐in electric field (BIEF) to enhance both catalytic stability and activity of Ru‐based catalysts in acidic environments. The constructed Co 3 O 4 @RuO 2 catalyst exhibits an OER overpotential of 189 mV and a HER overpotential of 55 mV at 10 mA cm −2 . When integrated into a proton exchange membrane water electrolysis (PEMWE) system, it requires only 1.68 V to reach 1000 mA cm −2 and maintains stable operation for 400 h with a degradation rate of only 14.5 µV h −1 . Experimental and theoretical results reveal that Co 3 O 4 acts as an invisible protective shield to facilitate proton consumption at the catalyst surface and mitigate the electron depletion at the Ru site, thus preventing the over‐oxidation and dissolution of Ru. Furthermore, the enriched active sites and reduced adsorption energy of intermediates significantly boost the catalytic performance, making this catalyst highly promising for hydrogen production applications.