Impact of Transition-Metal Doping of Ceria for Stabilization of Pd Single Atoms for Low-Temperature CO Oxidation

Ceria-supported Pd single-atom catalysts are promising materials for low-temperature CO oxidation; however, their performance is limited by sluggish low-temperature kinetics and aggregation of isolated Pd atoms. Using density functional theory and microkinetics simulations, we systematically investigate the effects of transition-metal (TM) doping on a Pd₁/CeO₂(111) single-atom catalyst model. We find that the influence of TM dopants is highly dopant-specific. Favorable TM dopants weaken CO adsorption on Pd, activate lattice oxygen, stabilize isolated Pd atoms, and open an alternative pathway that bypasses O₂ dissociation, collectively enhancing low-temperature activity compared to the undoped surface. Microkinetics simulations predict a markedly higher CO conversion rate for Fe-doped Pd₁/CeO₂(111) than for the undoped system. Random forest analysis reveals that adsorption and desorption govern the dominant reaction regimes, challenging the conventional emphasis on intrinsic kinetic barriers. These findings highlight the promise of TM doping as a strategy to enhance activity and stability of Pd/CeO₂ single-atom catalysts, offering valuable insights into their rational design for low-temperature CO oxidation.