Intermediate Confinement for Selective Ammonia Electrosynthesis from Nitrate on Robust Mesoporous Metal Catalysts

Abstract Mesoporous metals have received massive research interests in catalysis and electrocatalysis due to their unique structural features. However, most studies have focused on enhancing activity with much less focus on promoting selectivity. Here, it is reported that the design of bimetallic palladium‐copper (PdCu) alloys at mesoscopic level is a reliable and robust strategy to confine the reaction intermediate and thus boost nitrate reduction reaction (NITRR) electrocatalysis for selective NH₃ electrosynthesis. The optimized PdCu mesoporous nanospheres (MSs) disclose a high electrocatalytic NO₃⁻‐to‐NH₃ performance with NH₃ Faradaic efficiency () of 85%, yield rate of 3058 µg h⁻¹ mg⁻¹, energy efficiency of 31%, and multi‐turn stability. The combination of surface analysis and experimental techniques reveals that the high NO₃⁻‐to‐NH₃ performance results from highly penetrated and active mesoporous channels of PdCu MSs that not only kinetically facilitate the adsorption and reactivity of NO₃⁻ but also enhance the confinement of key intermediate (NO₂⁻) toward an eight‐electron NITRR pathway for selective NH₃ electrosynthesis. More importantly, in accompany with compositional control, trimetallic PdCuRu alloy MSs disclose a superior of 95% and an impressive NH₃ yield rate of 8518 µg h⁻¹ mg⁻¹ for selective NO₃⁻‐to‐NH₃ electroreduction.