Employing the alkaline water electrolysis system to generate hydrogen holds great prospects but still poses significant challenges, particularly for the construction of hydrogen evolution reaction (HER) catalysts operating at ampere-level current density. Herein, the unique Ru and RuP₂ dual nano-islands are deliberately implanted on N-doped carbon substrate (denoted as Ru-RuP₂/NC), in which a built-in electric field (BEF) is spontaneously generated between Ru-RuP₂ dual nano-islands driven by their work function difference. Experimental and theoretical results unveil that such constructed BEF could serve as the driving force for triggering fast hydrogen spillover process on bridged Ru-RuP₂ dual nano-islands, which could invalidate the inhibitory effect of high hydrogen coverage at ampere-level current density, and synchronously speed up the water dissociation on Ru nano-islands and hydrogen adsorption/desorption on RuP₂ nano-islands through hydrogen spillover process. As a result, the Ru-RuP₂/NC affords an ultra-low overpotential of 218 mV to achieve 1.0 A·cm⁻² along with the superior stability over 1000 h, holding the great promising prospect in practical applications at ampere-level current density. More importantly, this work is the first to advance the scientific understanding of the relationship between the constructed BEF and hydrogen spillover process, which could be enlightening for the rational design of the cost-effective alkaline HER catalysts at ampere-level current density.

Oxygen reduction reaction (ORR) plays an important role in the next-generation energy storage technologies, whereas it involves the sluggish and complicated proton-coupled electron transfer (PCET) steps that greatly limit the ORR kinetics. Therefore, it is urgent to construct an efficient catalyst that could simultaneously achieve the rapid oxygen-containing intermediates conversion and fast PCET process but remain challenging. Herein, the adjacent Fe₃C nanoparticles coupling with single Fe sites on the bubble-wrap-like porous N-doped carbon (Fe₃C@Fe_SA-NC) were deliberately constructed. Theoretical investigations reveal that the adjacent Fe₃C nanoparticles speed up the water dissociation and serve as proton-feeding centers for boosting the ORR kinetics of single Fe sites. Benefiting from the synergistic effect of the Fe₃C and single Fe sites, the Fe₃C@Fe_SA-NC affords an excellent half-wave potential of 0.88 V, and enables the assembled Zn-air batteries with the high peak power density of 164.5 mW·cm⁻² and long-term stability of over 200 h at high current densities at 50 mA·cm⁻². This work clarifies the mechanism for improving ORR kinetics of single atomic sites by engineering the adjacent proton-feeding centers, shedding light on the rational design of cost-effective electrocatalysts for energy conversion and storage technologies.