fig6

Figure 6. Non-noble metal electrocatalysts with low-index facets for the NtrRR. (A) SEM images of the Cu₂O with specific exposed facet (left panel) and the time-dependent in-situ FT-IR spectra: Cu₂O (100) and (111) electrocatalyst at -1.2 V vs. Ag/AgCl in nitrate solution (middle and right). Reproduced with permission^[47]. Copyright 2022, Elsevier; (B) Surface energy diagrams of Ni₂P with different orientations. Reproduced with permission^[48]. Copyright 2021, American Chemical Society; (C) The NtrRR free energy diagram of In₃Sn (100). Reproduced with permission^[17]. Copyright 2023, American Chemical Society; (D) Illustrative diagram of the V_Cu-Au₁Cu SAAs synthetic procedure (left panel) and differential charge densities of the Cu NSs (top), V-Cu NSs (middle), and V_Cu-Au₁Cu SAAs (bottom). Blue: charge depletion, red: charge accumulation (right). Reproduced with permission^[50]. Copyright 2022, Elsevier; (E) SEM images: Au/Cu SAAs. Reproduced with permission^[51]. Copyright 2023, American Chemical Society. SEM: Scanning electron microscope; FT-IR: Fourier transform infrared spectroscopy; SAAs: single-atom alloys.