Engineering MnO 2 Nanotubes@Co 3 O 4 Polyhedron Composite with Cross-linked Network Structure for Efficient Catalytic Oxidation of Formaldehyde

A novel cross-linked network structure of MnO 2 nanotubes@Co 3 O 4 polyhedron composite had been successfully prepared. Cobalt metal–organic framework (ZIF-67) in-situ grew on the open end of MnO 2 nanotubes. Via a thermal treatment, MnO 2 @ZIF-67 was transformed into MnO 2 @Co 3 O 4 . When the Mn/Co molar ratio was 4:5, MnO 2 @Co 3 O 4 -45 showed excellent catalytic performance and water-resistance, which could obtain 100% HCHO conversion at 60 °C. The superior catalytic performance was mainly contributed to the strong synergistic interaction originated from the coupled interface between MnO 2 and Co 3 O 4 . Moreover, the high percentage of Mn 4+ and Co 3+ , plenty surface active oxygen species and well low-temperature reducibility played important roles for the enhancement of catalytic activity. DFT simulations showed that MnO 2 @Co 3 O 4 exhibited the moderate adsorption capacity for HCHO, O 2 and H 2 O, facilitating desorption of products and then continuing to the next catalytic reaction. Reaction pathways were also proposed under different atmosphere by in situ DRIFTS analysis. Graphical Abstract