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

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 T_ig 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.