fig2

Figure 2. (A) Wannier functions of d orbitals and π^* orbital coupling in O₂ molecules with various adsorption configurations; (B) Correlation between adsorption strength and reaction barrier, with variation of -ICOHP for M–O_α and O_α–O_β bonds as a function of $$ d_{x^2-y^2} $$. Copyright 2024, American Chemical Society, Reproduced with permission^[56]; (C) Mechanism of “donation and backdonation” in N₂ adsorption on titanium: interaction between $$ d_{z^2} $$ orbital of Ti and 3σ orbital of N₂, and between d_XZ/d_YZ orbitals of Ti and 2π^* orbitals of N₂; (D) Coupling interactions between adsorbate states and both the average d-band center and spin-polarized d-band center: the complexity arising from d-orbital splitting and its influence on various adsorption behaviors. Copyright 2023, John Wiley and Sons, Reproduced with permission^[57]; (E) Illustration of ORR cycle: a comparison between experimental ORR mechanism and explored five-coordinate model, with the five-coordinate model predicting a closer starting potential to experimental results. Copyright 2022, American Chemical Society, Reproduced with permission^[59]; (F) Illustrative diagram of TM considered in this study, with distinct colors representing corresponding ranges of ORR/OER overpotentials (η); (g) Potential overvoltages for ORR and OER across all TM-N_x-C catalysts; Volcano plots for ORR (H) and OER (I) on the TM-N_x-C system. Copyright 2021, Springer Nature, Reproduced with permission^[60]. ORR: Oxygen reduction reaction; TM: transition metals; OER: oxygen evolution reaction.