DFT-Guided Design and Synthesis of Bipyridine-Anchored Copper Single-Atom Catalysts for Efficient Nitrate-to-Ammonia...

The electrochemical conversion of nitrate to ammonia represents an efficient approach to alleviate nitrate pollution, concurrently providing a sustainable strategy for ammonia synthesis. The development of cost-effective electrocatalysts that exhibit both high activity and selectivity in nitrate reduction reaction (NO₃RR) constitutes a substantial challenge. Herein, we demonstrate the rational design of single-atom catalysts (SACs) for the NO₃RR through theoretical screening and precise synthesis techniques. A series of bipyridine-anchored 3d transition metal SACs has been computationally pre-evaluated for their NO₃RR activity and selectivity, and bipyridine-Cu SAC stands out as the optimal candidate. Guided by the computational predictions, the bipyridine-Cu encapsulated inside a zirconium-containing metal-organic framework (namely Cu-SA/UiO-bpy) is synthesized and achieves an impressive ammonia yield rate of 7.4 mg_NH3 h^-1 cm^-2 and a faradaic efficiency of 98.1% in NO₃RR under neutral conditions. Additionally, Cu-SA/UiO-bpy exhibits remarkable catalytic performance (FE > 90%) across a wide pH range. In situ characterizations and theoretical calculations further reveal that bipyridine-Cu sites facilitate the interfacial dissociation of water and the efficient generation of reactive hydrogen species, enabling the selective hydrogenation of NO_x intermediates into ammonia. This integration of a data-driven approach with precise synthesis presents a novel paradigm for developing high-performance catalysts toward NO₃RR and other catalytic applications.