fig3

Figure 3. (A) Crystalline cFGDY was prepared for NH₃ synthesis from N₂ and H₂O at ambient conditions, showing 100% selectivity and excellent activity; (B) HRTEM image of cFGDY nanosheets; (C) Y_NH3 and FEs of cFGDY versus reported metal-free and metal-based catalysts^[79]; (A-C) are reprinted with permission from reference^[79]. Copyright 2020 The Royal Society of Chemistry; (D) Corresponding schematic illustration of HsGDY; (E) HRTEM image of HsGDY grown on Zn substrate; (F) Calculated NH₃ production rates at different potentials; (G) Concentrations of (NH₄)₂SO₄ in the electrolytes when ¹⁴N₂ and ¹⁵N₂ were used as the feed gases^[80]; (D-G) are reprinted with permission from reference^[80]. Copyright 2020 Elsevier; (H) Illustration of the Cl₂ etching process of GDY; (I) AFM image of Cl-GDY; (J) NH₃ production rates and FE of Cl-GDY; (K) ¹H NMR spectra of ¹⁵N₂- and ¹⁴N₂-fed electrolytes after electrolysis and of commercial ¹⁴NH₄Cl and ¹⁵NH₄Cl^[81]; (H-K) are reprinted with permission from reference^[81]. Copyright 2019 American Chemical Society; (L) Free-energy map of NRR over sp-N-2 GDY^[153]. Reprinted with permission from reference^[153]. Copyright 2021 Elsevier B.V. cFGDY: Crystalline fluorinated graphdiyne; HsGDY: hydrogen-substituted graphdiyne; RHE: reversible hydrogen electrode; HRTEM: high resolution transmission electron microscopy.