Precise Control of Active Site Configurations in High-Entropy Intermetallic Compounds for Electrocatalytic Nitrate Reduction to Ammonia.

High-entropy alloys (HEAs), composed of five or more elements in similar proportions, exhibit unique physicochemical properties, but their disordered atomic structures pose challenges in the precise control of active sites. In contrast, high-entropy intermetallic compounds (HEIs), with an ordered atomic arrangement and well-defined atomic positions, provide clear active site configurations, making them particularly advantageous for complex electrocatalytic reactions like the nitrate reduction reaction (NORR). Herein, we present the FeCoNiGeSb-HEI with precisely controlled elemental distributions, leading to the formation of distinct active sites. The FeCoNiGeSb-HEI catalyst exhibits high activity for NORR, achieving a high NH yield rate of 7.5 mg h cm at -0.4 V and a faradaic efficiency (FE) of 97.6% at -0.30 V, along with excellent stability. Density functional theory (DFT) calculations and experimental results reveal that Co sites act as key active sites, whereas Fe and Ni atoms contribute a synergistic effect. Additionally, the FeCoNiGeSb-HEI catalyst functions in a bifunctional system coupling NH production with the glycerol oxidation reaction (GOR), achieving an NH yield of 9.8 mg h cm at 1.8 V, maintaining stable performance for 100 h.