Fig. 2. Scaling of the free energy of the NH3 evolution at 25 °C (computed from tabulated free energy data as described in Section 3.1) via metal nitride (A) reduction and (B) hydrogenation with the product of the number of electrons in the metal ground state, N, and the energy of these electrons, E, in the (A) d-states and (B) s-states. The metal marks the metallic constituent of the composition given with ESI.† Solid lines are fits to the data shown with solid symbols.
