fig4

Figure 4. (A) Diagonal scatter plot of DFT-calculated versus machine learning predicted ∆G_H* on M-N₄-CNT(7, 7); (B) Exchange current density for DFT-calculated and machine learning predicted ∆G_H* on M-N₄-CNT(7, 7); (C) CI-NEB path and corresponding configurations for the Tafel mechanism on Fe-N₄-CNT(7, 7) with explicit water molecules; (D) CI-NEB path and corresponding configurations for the Heyrovsky mechanism on Fe-N₄-CNT(7, 7) with explicit water molecules. ML: Machine learning; ∆G_H*: Gibbs free energy of hydrogen adsorption; R²: coefficient of determination; RMSE: root mean square error; CNT: carbon nanotube; DFT: density functional theory; IS: Initial State; TS: Transition State; FS: Final State; CI-NEB: climbing-image nudged elastic band.