Termolecular Eley-Rideal pathway for efficient CO oxidation on phosphorene-supported single-atom cobalt catalyst

Density functional theory calculations are conducted to examine the oxidation of CO on a single Co atom anchored on a two-dimensional phosphorene monolayer (Co@Pn). The stability of the Co adatom on the Pn monolayer was revealed by ab initio molecular dynamics simulations. Three plausible pathways for CO oxidation over Co@Pn were explored: Langmuir-Hinshelwood (LH), Eley-Rideal (ER), and the recently proposed termolecular Eley-Rideal (TER) mechanisms. The TER pathway has a relatively lower energy barrier for the rate-determining step (0.55) than those of the LH (0.81) and ER (0.70 eV) pathways. The efficiency of TER pathway can be interpreted by CO-promoted O-2 activation via the effective formation of a five-membered ring composed of two CO and one O-2 molecules. The results open a new avenue for developing phosphorene-supported non-noble transition metal single-atom catalysts for various catalytic applications.