Exceptional Spatial Variation of Charge Injection Energies on Plasmonic Surfaces

Charge injection into a molecule on a metallic interface is a key step in many photoactivated reactions. We employ the many-body perturbation theory and compute the hole and electron injection energies for CO2 molecule on an Au nanoparticle with similar to 3,000 electrons and compare it to results for idealized infinite surfaces. We demonstrate a surprisingly large variation of the injection energy barrier depending on the precise molecular position on the surface. Multiple hot spots, characterized by low energy barriers, arise due to the competition between the plasmonic coupling and the degree of hybridization between the molecule and the substrate. The charge injection barrier to the adsorbate on the nanoparticle surface decreases from the facet edge to the facet center. This finding contrasts with the typical picture in which the electric field enhancement on the nanoparticle edges is considered the most critical factor.

Automated summary

Charge injection into a molecule on a metallic interface is a critical step in photoactivated reactions. We find that the precise molecular position on the surface can significantly affect the injection energy barrier, resulting in multiple low energy barriers due to the competition between plasmonic coupling and hybridization between the molecule and the substrate.