fig4

Figure 4. (A) Schematic diagram of adsorption configurations of diatomic molecules at single-atom site and dual-atom site. Reprinted with permission from Ref.^[88]. Copyright © 2022 Wiley-VCH GmbH; (B) N₂ molecule activation mechanism for the SACs and DACs. Reprinted with permission from Ref.^[89]. Copyright © 2020 The Authors. EcoMat published by John Wiley & Sons Australia; (C) Adsorption configuration and corresponding charge density difference of N₂ and free energy diagrams of NRR on Mn@C₂N and Mn₂@C₂N. Reprinted with permission from Ref.^[90]. Copyright © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. SACs: Single-atom catalysts; DACs: diatomic catalysts; NRR: nitrogen reduction reaction.