Reinforcing Oxygen Activation of Spinel Oxide via Mn─O Covalency Engineering for VOCs Oxidation

Removing VOCs efficiently demands catalysts that activate oxygen at low temperatures. Here, Mn─O covalency in MnCo spinel is strategically modulated through an in situ hard-templating method to incorporate Si and generate active oxygen species. Si incorporation induces Mn─O bond elongation and charge redistribution, weakening Mn─O covalency and forming Mn⁴⁺─O─Co³⁺ centers that promote dual activation of molecular and lattice oxygen. The optimized catalyst achieves T₉₀ of 168, 226, and 260°C for ethyl acetate, toluene, and propane, respectively, with excellent water resistance and long-term stability (100 h) for ethyl acetate oxidation. Combined in situ spectroscopy (DRIFTS and EXAFS) studies and DFT calculations reveal that weakened Mn─O covalency can accelerate the rate-limiting step of acetate oxidation to boost performance. This strategy can also be extended to synthesize MnO_x, Co₃O₄, and MnCeO_x for efficient VOC oxidation. Our work offers a new strategy to enhance oxygen activation via metal-oxygen covalency modulation for low-temperature VOC abatement.