Oxygen vacancy is conducive to molecular
oxygen adsorption and
activation, and it is necessary to estimate its contribution on catalysts,
especially the doped system for volatile organic compound (VOC) oxidation.
Herein, a series of doped Mn
x
Zr1–x
O2 catalysts with oxygen vacancy were
prepared by partially substituting Zr4+ in a zirconia with
low-valent manganese (Mn2+). Compared with the corresponding
mechanically mixed samples (MB-x) without oxygen vacancy, Mn
x
Zr1–x
O2 catalysts exhibited better toluene conversion and specific
reaction rate, where the differential values were calculated to estimate
the contribution of oxygen vacancy on catalytic performance. The increase
in oxygen vacancy concentrations in Mn
x
Zr1–x
O2 catalysts can
boost the differential values, implying the enhancement of oxygen
vacancy contribution. Density functional theory (DFT) calculations
further confirmed the contribution of oxygen vacancy, and molecular
oxygen is strongly absorbed and activated on a defective Mn-doped
c-ZrO2 (111) surface with oxygen vacancy rather than a
perfect m-ZrO2 (−111) surface or a perfect Mn-doped
c-ZrO2 (111) surface, thus resulting in the significant
improvement in catalytic activity for toluene oxidation. In situ DRIFTS
spectra revealed that the oxygen vacancy can alter the toluene degradation
pathway and accelerate the intermediates to convert into CO2 and H2O, thus leading to a low activation energy and
high specific reaction rate.
High-efficiency Pt/ZrO2 catalysts with a mixed phase were successfully prepared. The catalysts exhibited high activity and their interfacial structure can change the reaction pathway.
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