Metal organic framework-derived 3D nanostructured cobalt oxide as an effective catalyst for soot oxidation

Abstract

While Co3O4 represents one of the most promising catalysts for soot oxidation, conventional Co3O4 nanoparticles (NPs) tend to aggregate, losing their activities. Herein, an alternative approach is proposed for preparing three-dimensional nanostructured Co3O4 (NSCo) using the hierarchically-structured Co-based Metal Organic Frameworks as a precursor. Specifically, ZIF-67 is chosen as the precursor as ZIF-67 can be conveniently synthesized with high yields and it can be easily converted to NSCo via calcination. The resulting NSCo exhibits a unique morphology which enables NSCo to possess more porosities and surface areas than the typical Co3O4 NPs. Consequently, NSCo shows a much higher catalytic activity than the typical Co3O4 NPs for soot oxidation because of superior textural properties of NSCo. Besides, when the soot oxidation by the typical Co3O4 NPs produced a significant amount of unwanted CO, soot can be completely combusted into CO2 using NSCo. In comparison with other reported Co-related catalysts, NSCo also achieves a higher soot oxidation efficiency (100% conversion) at lower temperatures with Tig of 331 °C. NSCo can be reused over many continuous cycles and still retains its catalytic activities. These features validate that NSCo is an easy-to-prepare 3D nanostructured Co3O4 catalyst, which possesses advantageous capabilities for soot oxidation at lower temperatures.