The local ionization energy as a guide to site reactivities on graphenes

Abstract

The average local ionization energy I(r) has the very important practical advantage that its minimum values on molecular surfaces, the IS,min can generally identify the most reactive sites in a system in a single calculation, that encompasses all possible sites. The IS,min can also, in many instances, rank these sites. Our analyses have shown interaction energies for hydrogenation at interior carbons of defect-containing model graphenes correlate with the IS,min at these sites. Furthermore, we are able to show a relationship between the magnitude of the lowest interior IS,min within each member of a series of pristine and defect-containing graphene models and the corresponding hydrogenation energies. A limitation of I(r) that must be recognized is that it corresponds to the system prior to interaction, and cannot reflect factors that may accompany or follow it. Such factors may reinforce or oppose the predictions from the IS,min Considerable experience has shown, however, that the IS,min can generally identify satisfactorily at least the most reactive sites—and can often rank the next ones as well.