fig2

Figure 2. (A) Schematic illustration of five possible mechanisms (consecutive, enzymatic, alternative, distal, and mixed) for NRR. Reprinted with permission from Ref.^[22]. Copyright © 2021, American Chemical Society; (B) MvK mechanism for NRR. Reprinted with permission from Ref.^[23]. Copyright © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim; (C) Enzyme-distal mechanism for NRR. Reprinted with permission from Ref.^[24]. Copyright © 2021 Dalian Institute of Chemical Physics, the Chinese Academy of Sciences; (D) N₂ dissociation mechanism under confined dual sites (pink and blue spheres denote metal and nitrogen atoms, respectively; IS, TS, and FS denote initial, transition, and final states, respectively). Reprinted with permission from Ref.^[25]. Copyright © 2024 National Academy of Sciences; (E) Reaction mechanism for NRR on Rh surface. Reprinted with permission from Ref.^[26]. Copyright © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim; (F) Schematic of surface-hydrogenation mechanism for NRR on noble-metal-based catalysts. Reprinted with permission from Ref.^[27]. Copyright © 2019 American Chemical Society. NRR: Nitrogen reduction reaction; MvK: Mars-van-Krevelen; IS: initial state; TS: transition state; FS: final state.