Fig. 4. (a) Adsorption free energies of H atoms (ΔG H) on the Ni(111) (blue) and h-BN/Ni(111) (green) surfaces with H coverage at 1/4, 1/2, and 1 ML. The optimal value of ΔG H for the best HOR activity is shown by the red dashed line. (b) Adsorption energies of OH atoms (ΔE OH) on the Ni(111) (blue) and h-BN/Ni(111) (green) surfaces with OH coverage at 1/4, 1/2, and 1 ML. (c) Adsorption energies of O atoms (ΔE O) on the Ni(111) (blue) and h-BN/Ni(111) (green) surfaces with O coverage at 1/4, 1/2, and 1 ML.
