Mechanistic insight into the dispersion behavior of single platinum atom on monolayer g-C3N4 in single-atom catalysts from density functional theory calculations

Abstract

Single-atom catalysts (SACs) are an effective strategy for the efficient and low-cost utilization of noble metals. However, it remains a huge challenge to obtain atomically dispersed SACs. In this work, the dispersion behavior of single platinum atoms on pristine monolayer g-C3N4 has been investigated by DFT calculations. The calculation results show that the diffusion of single atom Pt on pristine monolayer g-C3N4 has characteristics of anisotropy. More importantly, the migration and aggregation of single atom Pt within the global scope of monolayer g-C3N4 can be effectively avoided, while in the local scope, the migration of single atom Pt is easy, and single atom Pt clustering is inevitable. Significantly, it can be predicted that stable SACs can be synthesized when the coverage of single atom Pt is less than the density of six-fold cavity. Moreover, it is found that the Pt clusters confined in the six-fold cavity of monolayer g-C3N4 are very stable and difficult to migrate on monolayer g-C3N4. And, the larger the size of Pt clusters confined in monolayer g-C3N4, the more difficult to separate a Pt atom from the Pt clusters. These results indicate that the Pt clusters confined in monolayer g-C3N4 have an effective Ostwald ripening mechanism.