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 mgcat.-1 or 69.4 mg h-1 mgAg-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.