Enhancing catalytic toluene oxidation over MnO2@Co3O4 by constructing a coupled interface

Herein, a bottom-down design is presented to successfully fabricate ZIF-derived Co 3 O 4 , grown in situ on a one-dimensional (1D) α-MnO 2 material, denoted as α-MnO 2 @Co 3 O 4 . The synergistic effect derived from the coupled interface constructed between α-MnO 2 and Co 3 O 4 is responsible for the enhanced catalytic activity. The resultant α-MnO 2 @Co 3 O 4 catalyst exhibits excellent catalytic activity at a T 90% (temperature required to achieve a toluene conversion of 90%) of approximately 229 o C, which is 47 and 28 °C lower than those of the pure α -MnO 2 nanowire and Co 3 O 4 -b obtained via pyrolysis of ZIF-67, respectively. This activity is attributed to the increase in the number of surface-adsorbed oxygen species, which accelerate the oxygen mobility and enhance the redox pairs of Mn 4+ /Mn 3+ and Co 2+ /Co 3+ . Moreover, the result of in situ diffuse reflectance infrared Fourier transform spectroscopy suggests that the gaseous oxygen could be more easily activated to adsorbed oxygen species on the surface of α-MnO 2 @Co 3 O 4 than on that of α-MnO 2 . The catalytic reaction route of toluene oxidation over the α -MnO 2 @Co 3 O 4 catalyst is as follows: toluene → benzoate species → alkanes containing oxygen functional group → CO 2 and H 2 O. In addition, the α -MnO 2 @Co 3 O 4 catalyst shows excellent stability and good water resistance for toluene oxidation. Furthermore, the preparation method can be extended to other 1D MnO 2 materials. A new strategy for the development of high-performance catalysts of practical significance is provided. The resultant α-MnO 2 @Co 3 O 4 catalyst with a coupled interface shows better catalytic activity than the pure α-MnO 2 , which is ascribed to the increased number of surface-adsorbed oxygen species, which accelerate the oxygen mobility and enhance the redox pairs of Mn 4+ /Mn 3+ and Co 2+ /Co 3+ .