Constructing oxygen vacancies for δ-MnO₂ based monolithic catalyst by Cu intercalation to enhance toluene oxidation

The construction of monolithic catalysts is indispensable for the practical application of thermal catalytic oxidation technology in volatile organic compounds (VOCs) degradation. In this work, a feasible molten salt method is employed to simultaneously construct the Cu intercalated ultrathin δ-MnO₂ nanosheet and in situ support it on Ni foam. The resulting monolithic catalyst exhibits a remarkable enhancement on catalytic performance of toluene oxidation compared with the pristine δ-MnO₂ supported on Ni foam. Microstructure studies suggest that the interlayer Cu of δ-MnO₂ with two-dimensional structure can enhance the disorder of MnO₂ lattice, which promotes the formation and exposure of numerous oxygen vacancies and enables lattice oxygen reactivity. Consequently, oxygen activation is improved to generate abundant reactive oxygen species and lattice oxygen is more easily activated, which can accelerate the production and consumption of intermediates during toluene oxidation. This research proposes new insights of designing monolithic catalysts with abundant oxygen vacancies for efficient VOCs oxidation.