Atomic-Scale Charge Distribution Mapping of Single Substitutional p- and n-Type Dopants in Graphene

Tuning the chemical properties of graphene by controlled doping is a widely investigated strategy. The effect of a substitutional single dopant on graphene local reactivity is much less explored. To improve the understanding of the role of p- and n-type dopants in graphene's local chemical activity and quantification of its interaction with single molecules, we report an atomic-scale investigation of single boron (B) and nitrogen (N) dopants in graphene and their interactions with CO molecules by means of atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM) experiments and theoretical calculations. We infer that N/B doping significantly increases/lowers the chemical interaction of graphene with individual CO molecules as a result of weak electrostatic forces induced by distinct charge distribution around the dopant site. High-resolution AFM images allow dopant discrimination and their atomic-scale structural characterization, which may be crucial for the atomic-scale design of graphene derivatives with relevant potential applications in molecular sensing and catalysis.