Single-atom Cu anchored on Mo 2 C boosts nitrite electroreduction to ammonia.

We design single-atom Cu anchored on Mo 2 C (Cu 1 /Mo 2 C) as an effective electrocatalyst towards electrochemical nitrite reduction to ammonia (NO 2 RR), exhibiting an NH 3 -faradaic efficiency of 91.5% with a corresponding NH 3 yield rate of 472.9 μmol h -1 cm -2 at -0.6 V vs. RHE. Theoretical computations unravel that single-atomic Cu couples with the surface Mo atom of Mo 2 C to enable the construction of Cu-Mo dual-active centers, which can synergistically activate NO 2 - and minimize the NO 2 - -to-NH 3 reaction energy barrier, whilst suppressing the competing hydrogen evolution reaction.