Revealing the Jahn–Teller Mitigating Complexity of Se-Anchored Mn Oxides for Superior SO2 Resistance in Gaseous Molecular Oxygen Activation

Abstract

Manganese oxides have emerged as promising catalysts for the low-temperature activation of molecular oxygen (O₂), crucial for the catalytic oxidation and removal of gaseous pollutants. However, the undesired Jahn–Teller (J-T) effects associated with the Mn^iv/Mnⁱⁱⁱ redox couple, particularly under SO₂ poisoning, led to the effectiveness of Mn oxides in applications. Herein, we construct a highly covalent Se^iv-O-Mnⁱⁱⁱ structure via the introduction of selenium into α-MnO₂. Such a structure features high-valence Se^iv anchored on the oxygen-terminated (110) plane of α-MnO₂, facilitates the generation of more active oxygen species, and maintains the continuous cycling of oxygen-linked Mn^iv/Mnⁱⁱⁱ. Such dynamics are pivotal for stabilizing manganese activation and mitigating the J-T effect. Through a combination of experimental investigations and theoretical calculations, we demonstrate that the Se^iv-O-Mnⁱⁱⁱ configuration, characterized by a high degree of Mn–O hybridization, significantly enhances CO oxidation, NH₃ oxidation, and elemental mercury (Hg⁰) removal performances, and exhibits resistance to SO₂. This study paves the way for the development of efficient low-temperature O₂ activation processes for the removal of gaseous pollutants in real-world applications.