Iron Diboride (FeB 2 ) for the Electroreduction of NO to NH 3 .

We report iron diboride (FeB 2 ) as a high-performance metal diboride catalyst for electrochemical NO-to-NH 3 reduction (NORR), which shows a maximum NH 3 yield rate of 289.3 μmol h -1 cm -2 and a NH 3 -Faradaic efficiency of 93.8% at -0.4 V versus reversible hydrogen electrode. Theoretical computations reveal that Fe and B sites synergetically activate the NO molecule, while the protonation of NO is energetically more favorable on B sites. Meanwhile, both Fe and B sites preferentially absorb NO over H atoms to suppress the competing hydrogen evolution.