The strong polarization effect of lanthanide metals for efficient alkaline hydrogen evolution

Alkaline water (H₂O) electrolysis represents a commercially viable route for green hydrogen (H₂) production, but its efficiency remains fundamentally limited by the sluggish hydrogen evolution reaction (HER) kinetics. Herein, we synthesized PtRuLaPrEu high-entropy alloy aerogels (HEAAs) <i>via</i> a freeze-thaw synthesis strategy as a high-performance alkaline HER catalyst. The PtRuLaPrEu HEAAs achieve an ultralow overpotential of 19.2 mV at 10 mA cm^-2, outperforming PtRu metal aerogels (MAs, 55.7 mV) and commercial Pt/C (93.1 mV), with a lower Tafel slope of 32 mV dec^-1. Mechanism studies reveal that the excellent alkaline HER performance of the PtRuLaPrEu HEAAs is attributed to the strong polarization effect of the lanthanide elements (La, Pr, and Eu), which induces interfacial electric fields that promote H₂O polarization, facilitating the dynamic reconstruction of the optimized hydrogen-bond networks at the catalyst-electrolyte interface, accelerating the proton transfer kinetics. This work establishes a new paradigm for synergistic electronic structure engineering and interfacial microenvironment control in advanced electrocatalyst design.