Evaluating the Stability of Single-Atom Catalysts with High Chemical Activity

Single-atom catalysts represent the most efficient use of precious metals while at the same time offering the potential for high catalytic activity. Yet it has proven challenging to identify supports enabling high catalytic activity while at the same time inhibiting aggregation of metal adatoms. Density functional theory calculations are employed to identify how the local molecular environment on graphene can be used to stabilize a single platinum adatom and provide favorable activity for a benchmark reaction, CO oxidation. Graphene is modified via defects and dopants-specifically single vacancy and pyridinic N-doping so that we can see how the electronic structure and chemical activity of Pt atoms are affected. The ability to disperse single atoms on graphene supports is examined by comparing binding energy of Pt atoms at neighboring stable sites versus isolated sites and evaluating the tendency toward clustering. Nudged elastic band calculations indicate that pyridinic N-doped graphene is a promising candidate to support a single Pt atom acting as a catalyst that is resistant to poisoning and enhances CO oxidation efficiency.