Constructing the confined RuCo nanoalloys with modulated d-band centers for efficient pH-robust hydrogen evolution

The development of pH‐robust electrocatalysts is highly desirable but challenging for the hydrogen evolution reaction (HER) in water electrolysis. Among the noble metal groups, ruthenium (Ru) holds the promise in balancing the cost and activity in HER, but it is restricted by the strong H adsorption and the sluggish Heyrovsky step. It appeals for a rational d-band manipulation to neutralize the hydrogen adsorption to promote the HER kinetics. Herein, we profiled a confined structure with RuCo alloy nanoparticles in N-doped carbon nanofiber (RuCo@NCNF) by a facile electrospinning-pyrolysis process for HER electrocatalysis. An electron transfer from Co to Ru is indicated in the RuCo@NCNF composite to enhance the electron-donating character of Ru active sites to couple the HER. Resultantly, the optimized Ru₁Co_2.5@NCNF catalyst stably exhibits the Pt-beyond HER activity in both alkaline (10 mV at 10 mA cm⁻²) and acidic electrolytes (23 mV at 10 mA cm⁻²), while delivering competitive HER performance in neutral electrolytes. Density functional theory (DFT) calculations also confirm that the Ru-Co electronic interactions can effectuate the d-band center downshift, moderating the adsorption energies of hydrogen (ΔG_H*) and H₂O for efficient hydrogen production. This study provides a reference for the rational design of Ru-based pH-robust HER electrocatalyst through confined nanoalloy structures.