Self-surfactant effect in graphene growth on Pt(111)

Graphene, a material with exceptional physicochemical properties, has been synthesized on a variety of substrates. However, prior theoretical studies have suggested that carbon (C) clusters are typically less stable thermodynamically compared to individual C monomers on most transition metal substrates. Taking the Pt(111) surface as a case study, we introduce a unified mechanism termed the ``self-surfactant effect'' that promotes the efficient growth of graphene on Pt(111). This mechanism incorporates two key processes: edge passivation and repulsion minimization. The self-surfactant effect serves as an essential bridge between theoretical predictions and experimental observations, enhancing the growth of graphene in two ways: (1) by strengthening the interaction between C clusters and the substrate through edge passivation, and (2) by minimizing repulsion between the inner atoms of C clusters and the substrate. Intriguingly, our results reveal a linear correlation between the formation energies of C clusters on the Pt(111) surface and the ratio of peripheral atoms to the total number of atoms within the clusters. These insights not only advance our understanding of graphene growth but may also have broader implications for other heteroepitaxial systems.