N‐Coordinated Cu–Ni Dual‐Single‐Atom Catalyst for Highly Selective Electrocatalytic Reduction of Nitrate to Ammonia

Abstract

As a traditional method of ammonia (NH₃ ) synthesis, Haber-Bosch method expends a vast amount of energy. An alternative route for NH₃ synthesis is proposed from nitrate (NO₃ ^- ) via electrocatalysis. However, the structure-activity relationship remains challenging and requires in-depth research both experimentally and theoretically. Here an N-coordinated Cu-Ni dual-single-atom catalyst anchored in N-doped carbon (Cu/Ni-NC) is reported, which has competitive activity with a maximal NH₃ Faradaic efficiency of 97.28%. Detailed characterizations demonstrate that the high activity of Cu/Ni-NC mainly comes from the contribution of Cu-Ni dual active sites. That is, (1) the electron transfer (Ni → Cu) reveals the strong electron interaction of Cu-Ni dual-single-atom; (2) the strong hybridizations of Cu 3d-and Ni 3d-O 2p orbitals of NO₃ ^- can accelerate electron transfer from Cu-Ni dual-site to NO₃ ^- ; (3) Cu/Ni-NC can effectively decrease the rate-limiting step barriers, suppress N-N coupling for N₂ O and N₂ formation and hydrogen production.