Unveiling the Synergy of Delocalized O 2p Holes and Localized Ce 4f States for Enhanced NH3-SCR Activity on WO3/La-CeO2 Catalyst

Abstract

NH₃-selective catalytic reduction (NH₃-SCR) is a key technology for efficient NO_x removal, yet its performance remains fundamentally limited by sluggish NH₃ activation and redox kinetics over conventional catalysts. Although heterovalent doping (e.g., La) is widely employed to enhance the NH₃-SCR activity of ceria-based catalysts, the underlying electronic mechanism remains elusive. Herein, spin-polarized density functional theory calculations corrected by on-site Coulomb interactions reveal that La doping induces delocalized O 2p holes on WO₃/La-CeO₂(111), which serve as the primary electron reservoir during the NH₃-SCR reaction. These delocalized O 2p holes can work synergistically with the localized Ce 4f states to accommodate the redistributed charges, lowering the activation barrier for NH₃ dissociation. This synergistic effect also affects the N-N coupling stage, where dynamic electron transfer between Ce 4f states and O 2p holes stabilizes the migration of NH₂ species. As the result, such La-induced O 2p holes provide a significant thermodynamic driving force for the overall reaction. Our work establishes the synergy between delocalized O 2p holes and localized Ce 4f states as the origin of La-promoted NH₃-SCR activity, providing a rational strategy for designing high-performance catalysts via electronic structure engineering. These insights highlight that heterovalent doping can effectively tune the redox properties of lattice oxygen in ceria-based catalysts and may provide theoretical guidance for the development of efficient vanadium-free NH₃-SCR systems.