CeCoOx-MNS catalyst derived from three-dimensional mesh nanosheet Co-based metal–organic frameworks for highly efficient catalytic combustion of VOCs

Hierarchical MnOx/Co3O4 Nanoarrays on Ni Foam for Catalytic Oxidation of Volatile Organic Compounds

“…The peaks at 529.8, 531.3, and 533.0 eV were classified as O α , O β , and O γ , respectively. Previous studies have found that O α played key role in the catalytic combustion of VOCs. ,, Interestingly, the order of O α /O tatal ( O total = O α + O β + O γ ) ratio on these catalysts followed MnO x /Co 3 O 4 /NF > Co 3 O 4 /MnO x /NF > Co 3 O 4 /NF > MnO x /NF. XPS can semiquantitatively calculate the surface composition of the catalyst; however, it cannot detect bulk oxygen species in these catalysts.…”

“…Figure b showed that the Raman spectrum of the prepared monolithic catalyst. For the Raman spectrum of the Co 3 O 4 /NF catalyst, five Raman modes at about 196, 479, 521, 600, and 677 cm –1 could be attributed to the F 2g , E g , F 2g , F 2g , and A 1g peaks of Co 3 O 4 phase. , The peak located 196 cm –1 is attributed to the F 2g mode of tetrahedral CoO 4 site and the peak located 677 cm –1 is attributed to the A 1g mode, which corresponded to the tensile vibration of the octahedral CoO 6 part of Co 3 O 4 phase . For the MnO x /NF catalyst, the three major peaks identified at 510, 583, and 646 cm –1 are Mn–O single bond stretching of δ-MnO 2 .…”

“…At the same time, the MnO x /Co 3 O 4 /NF presented a higher cobalt concentration in the low state, which can be regarded as a sensitive indicator of a highly defective structure (oxygen deficiency) and can help to activate oxygen molecules into active oxygen. 33 Therefore, it was concluded that the hierarchical MnO x /Co 3 O 4 /NF catalyst has a highly defective structure, and this structure could generate more reactive oxygen and accelerate the adsorption of the reaction species.…”

“…Therefore, in the absence of gas-phase oxygen, the reaction pathway of toluene oxidation should be followed as toluene → benzoate → benzoquinone → maleate and maleic anhydride →••• → CO 2 and H 2 O. 29,33 Specifically, the absence of gaseous oxygen conducted the oxidation of toluene by lattice oxygen and the redox between Co and Mn ions (Co 3+ + Mn 2+ → Co 2+ + Mn 3+ + Mn 4+ ). 33 Since the variability among the mixed Co 3+ , Co 2+ , Mn 4+ , Mn 3+ , and Mn 2+ allows the exchange of electrons, redox cycles are prone to occur.…”

“…29,33 Specifically, the absence of gaseous oxygen conducted the oxidation of toluene by lattice oxygen and the redox between Co and Mn ions (Co 3+ + Mn 2+ → Co 2+ + Mn 3+ + Mn 4+ ). 33 Since the variability among the mixed Co 3+ , Co 2+ , Mn 4+ , Mn 3+ , and Mn 2+ allows the exchange of electrons, redox cycles are prone to occur. Besides, the enhancement of CO 2 band indicated that the higher transfer ratio of O latt , the better the activity of total toluene oxidation.…”