Single‐Atom Bi Alloyed Pd Metallene for Nitrate Electroreduction to Ammonia

Electrochemical reduction of nitrate to ammonia (NO3RR) holds a great promise for attaining both NH3 electrosynthesis and wastewater purification. Herein, single-atom Bi alloyed Pd metallene (Bi1Pd) is reported as a highly effective NO3RR catalyst, showing a near 100% NH3-Faradaic efficiency with the corresponding NH3 yield of 33.8 mg h(-1) cm(-2) at -0.6 V versus RHE, surpassing those of almost all ever reported NO3RR catalysts. In-depth theoretical and operando spectroscopic investigations unveil that single-atom Bi electronically couples with its neighboring Pd atoms to synergistically activate NO3- and destabilize *NO on Bi1Pd, leading to the reduced energy barrier of the potential-determining step (*NO ->*NOH) and enhanced protonation energetics of NO3--to-NH3 pathway.