fig6

Figure 6. (A) Design and operation of the Cu₃N/GDY catalyst for NtRR; (B) HRTEM image of the Cu₃N/GDY catalyst; (C) Y_NH3 and FEs of the Cu₃N/GDY and the other samples at different potentials; (D) Comparison of Cu₃N/GDY with recently reported catalysts. (The nitrate concentrations of these reports are equal to or exceed 0.1 M)^[89]; (A-D) are reprinted with permission from reference^[89]. Copyright 2024 American Chemical Society; (E) Electron beam irradiation synthesis; (F) HRTEM image of Cu₂O/GDY NtRR performance and mechanistic analysis; (G) NH₃ yield rates and FEs at different Cu loadings and (H) for Cu₂O/GDY at different potentials^[90]; (E-H) are reprinted with permission from reference^[90]. Copyright 2025 Wiley-VCH GmbH; (I) Synthesis routes of CuCo₂Ox/GDY; (J) HRTEM image showing the lattice fringes and high-angle grain boundaries of CuCo₂O_x/GDY; (K) Comparison of Y_NH3 and FEs of CuCo₂Ox and CuCo₂Ox/GDY; (L) Free energy diagram for CuCo₂Ox/GDY and CuCo₂Ox^[92]; (I-L) are reprinted with permission from reference^[92]. Copyright 2025 Wiley-VCH GmbH; (M) Synthesis routes to GDY-MnO_x; (N) HRTEM image of GDY-MnO_x; (O) FEs and Y_NH3 of GDY-MnO_x at different potentials; (P) ¹H NMR of electrolytes following reduction of ¹⁵NO₃^- and ¹⁴NO₃^-[95]; (M-P) are reprinted with permission from reference^[95]. Copyright 2023 The Royal Society of Chemistry. GDY: Graphdiyne; RHE: reversible hydrogen electrode; HEB-TMS: Hexakis-[(trimethylsilyl)ethynyl]benzene; FE: Faradaic efficiency; NtRR: nitrate reduction reaction; HRTEM: high resolution transmission electron microscopy.