Synergistic Electronic Modulation via Dual‐Atomic Site Engineering in RuCo Hybrids for Optimized Hydrogen Adsorption and Enhanced Overall Water Splitting

Abstract Developing hydrogen as a clean, sustainable energy carrier relies on green electricity‐derived large‐scale water splitting production. However, it is greatly limited by the inherently sluggish reaction kinetics and high energy barriers associated with proton reduction. Herein, the study proposes heterostructured RuCo‐nanocubes (RuCo‐NC) engineered through phase control and metal integration to optimize hydrogen adsorption, enhancing catalytic efficiency by reducing energy barriers and improving mass and charge transport. Experimental and theoretical analyses revealed that incorporating Ru into Co‐NC induces electron redistribution and enhances the proton source, while reducing the adsorption of H^* on RuCo‐NC, thereby facilitating hydrogen spillover and accelerating HER kinetics. Consequently, the RuCo‐NC catalyst achieves 10 and 100 mA cm⁻² current densities with overpotentials of just 15 and 76 mV, under alkaline conditions, outperforming most Ru‐based catalysts and benchmark Pt/C. The assembled RuCo‐NC || Ir/C electrolyzer shows an excellent energy‐saving effect for water‐splitting, achieving the cell voltages of 1.510 and 1.731 V, at 10 and 100 mA cm⁻² current densities, respectively, with stable operation for over 120 h. This novel approach offers designing highly efficient HER electrocatalysts with low noble metal content through tailored structural features and interfacial synergy to accelerate proton reduction kinetics.