Vanadium Diboride (VB 2 ) for NO Electroreduction to NH 3 .

We report VB as an efficient electrocatalyst for NO-to-NH electroreduction (NORR), showing the highest NH-Faradaic efficiency of 89.6% with the corresponding NH yield rate of 198.3 μmol h cm at -0.5 V vs RHE. Theoretical calculations demonstrate that B sites of VB act as the key active centers which can facilitate the NORR protonation energetics and inhibit the competitive hydrogen evolution, boosting both NORR activity and selectivity.