fig7

Figure 7. (A) The synthetic strategy of Fe_x-GDY/Gra; (B) Comparisons of free energies of PLS for the NRR and HER on Fe_x-GDY/Gra; (C) Reaction path and free energy of Fe₃-GDY/Gra with respect to NRR^[140], Copyright 2020 The Royal Society of Chemistry; (D) The free energy of transition state for N₂ dissociation, hydrogenation barrier of ^*N + ^*NH formation, and desorption energy of NH₃ on14 three-atom metal clusters; (E) Binding energy of M₃ metal clusters on N₂ and H₂; (F) Free energy diagram of NRR reaction on Y₃/G; (G) Free energy diagram of NRR reaction on Nb₃/G^[26], Copyright 2022, American Chemical Society; (H) Two modes of N₂ adsorption free energy on Fe_xMo_y-CNs; (I) Preliminary and final reaction free energies on different Fe_xMo_y-CNs; (J) Reaction free energy tendency model on different Fe_xMo_y-CNs; (K) The diagram of UL_(NRR)−UL_(HER) vs. UL_(NRR) relationship and the colored area shows better performance^[70]. PLS: Potential-limiting step; NRR: N₂ reduction reaction; HER: hydrogen evolution reaction.