REEs enhance catalytic activity through several mechanisms: - Electronic Effects: The 4f orbitals of REEs can interact with the d orbitals of transition metals, modifying their electronic properties and improving their catalytic performance. - Structural Effects: REEs can stabilize various catalytic phases, preventing sintering and deactivation. - Redox Properties: Many REEs, such as cerium, exhibit multiple oxidation states, which can facilitate redox reactions crucial for catalytic processes.
