fig4

Figure 4. (A) Schematic illustration of IVR-FO/GDY preparation; (B) SEM of IVR-FO/GDY; (C) Y_NH3 and FEs of the samples at different potentials in N₂-saturated 0.1 M Na₂SO₄ (error bars represent the standard deviation)^[82]; (A-C) are reprinted with permission from reference^[82]. Reproduced under the CC BY 4.0 license; (D) Synthesis of self-supported GDY/Co₂N; (E) TEM image of GDY/Co₂N. NRR performance of GDY/Co₂N in (F) neutral media^[83]; (D-F) are reprinted with permission from reference^[83]. Copyright 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim; (G) Schematic diagram of the ammonia production process on porous GDY@CoO_xQD; (H) HRTEM images of porous GDY@CoO_xQD nanosheets; (I) Y_NH3 of the samples in different electrolytes^[160]; (G-I) are reprinted with permission from reference^[160]. Copyright 2021 Elsevier; (J) Preparation and reaction route for GDY@Fe-B; (K) HRTEM images of GDY@Fe-B; (L) Y_NH3 obtained after the stability test^[161]; (J-L) are reprinted with permission from reference^[161]. Copyright 2020 Wiley-VCH GmbH. IVR-FO/GDY: Iron vacancy (VFe)-rich ferroferric oxide on GDY; HEB: hexaethynylbenzene; CC: carbon cloth; FE: Faradaic efficiency; RHE: reversible hydrogen electrode; SEM: scanning electron microscope; NRR: nitrogen reduction reaction; TEM: transmission electron microscope; HRTEM: high resolution transmission electron microscopy.