Enhanced Alkaline Hydrogen Evolution Reaction through Lanthanide‐Modified Rhodium Intermetallic Catalysts

Abstract Design of highly efficient electrocatalysts for alkaline hydrogen evolution reaction (HER) is of paramount importance for water electrolysis, but still a considerable challenge because of the slow HER kinetics in alkaline environments. Alloying is recognized as an effective strategy to enhance the catalytic properties. Lanthanides (Ln) are recognized as an electronic and structural regulator, attributed to their unique 4f electron behavior and the phenomenon known as lanthanide contraction. Here, a new class of Rh 3 Ln intermetallics (IMs) are synthesized using the sodium vapor reduction method. The alloying process induced an upshift of the d‐band center and electron transfer from Ln to Rh, resulting in optimized adsorption and dissociation energies for H 2 O molecules. Consequently, Rh 3 Tb IMs exhibited outstanding HER activity in both alkaline environments and seawater, displaying an overpotential of only 19 mV at 10 mA cm −2 and a Tafel slope of 22.2 mV dec −1 . Remarkably, the current density of Rh 3 Tb IMs at 100 mV overpotential is 8.6 and 5.7 times higher than that of Rh/C and commercial Pt/C, respectively. This work introduces a novel approach to the rational design of HER electrocatalysis and sheds light on the role of lanthanides in electrocatalyst systems.