Interfacial work function matching enables efficient hydrogen spillover for superior alkaline hydrogen evolution

The sluggish kinetics of alkaline hydrogen evolution reaction (HER) governed by the consecutive steps of water adsorption/dissociation and hydrogen desorption remains a major obstacle to efficient green hydrogen production. Though hydrogen spillover offers a promising strategy to bridge these steps, it requires overcoming high energy barriers at the metal-support interface as a prerequisite.

This study aims to design a hydrogen spillover-based binary metal-based electrocatalyst by precisely tailoring work function difference (ΔΦ) and d-band center offset (Δε_d) at the metal-metal interface, thereby minimizing the interfacial energy barrier and enhancing HER performance.

We report the rational design of Ni_xRu_y nanocrystals anchored on Cu nanorods (Ni_xRu_y@Cu), wherein the ΔΦ and Δε_d are precisely tailored to minimize the interfacial energy barrier for hydrogen spillover.

The combination of operando electrochemical measurements, electrochemical analysis and density functional theory (DFT) calculations demonstrate that the optimal Ni₁Ru₂@Cu achieves an ultralow ΔΦ of 0.03 eV, between Ni₁Ru₂ alloy and Cu, enabling efficient hydrogen spillover from NiRu alloys to the Cu support. This results in exceptional HER performance, requiring only 57 mV overpotential to reach 20 mA cm^-2 and a small Tafel slope of 81.7 mV dec^-1, alongside remarkable long-term stability.

This work not only establishes a general paradigm for the design of advanced hydrogen spillover-based catalysts but also provides fundamental insights into multi-step reactions involving hydrogen intermediates, paving the way for high-performance alkaline water electrolysis.