Highly Productive Electrosynthesis of Ammonia by Admolecule-Targeting Single Ag Sites

The ambient electrocatalytic N₂ reduction reaction (NRR) is a promising alternative to the Haber-Bosch process for producing NH₃. However, a guideless search for single-atom-based and other electrocatalysts cannot promote the NH₃ yield rates by NRR efficiently. Herein, our first-principles calculations reveal that the successive emergence of vertical end-on *N₂ and oblique end-on *NNH admolecules on single metal sites is key to high-performance NRR. By targeting the admolecules, single Ag sites with the Ag-N₄ coordination are found and synthesized massively. They exhibit a record-high NH₃ yield rate (270.9 μg h^-1 mg_cat.^-1 or 69.4 mg h^-1 mg_Ag^-1) and a desirable Faradaic efficiency (21.9%) in HCl aqueous solution under ambient conditions. The generation rate of NH₃ is stable during 20 consecutive reaction cycles, and the reduction current density is almost constant for 60 h. This work provides an effective targeting-design principle to purposefully synthesize active and durable single-atom-based NRR electrocatalysts.