Enhanced Alkaline Hydrogen Evolution Reaction via Electronic Structure Regulation: Activating PtRh with Rare Earth Tm Alloying

Abstract Developing high‐performance electrocatalysts for alkaline hydrogen evolution reaction (HER) is crucial for producing green hydrogen, yet it remains challenging due to the sluggish kinetics in alkaline environments. Pt is located near the peak of HER volcano plot, owing to its exceptional performance in hydrogen adsorption and desorption, and Rh plays an important role in H 2 O dissociation. Lanthanides (Ln) are commonly used to modulate the electronic structure of materials and further influence the adsorption/desorption of reactants, intermediates, and products, and noble metal‐Ln alloys are recognized as effective platforms where Ln elements regulate the catalytic properties of noble metals. Here Pt 1.5 Rh 1.5 Tm alloy is synthesized using the sodium vapor reduction method. This alloy demonstrates superior catalytic activity, being 4.4 and 6.6 times more effective than Pt/C and Rh/C, respectively. Density Functional Theory (DFT) calculations reveal that the upshift of d‐band center and the charge transfer induced by alloying promote adsorption and dissociation of H 2 O, making Pt 1.5 Rh 1.5 Tm alloy more favorable for the alkaline HER reaction, both kinetically and thermodynamically.