Morphology control of cobalt oxide nanocrystals for promoting their catalytic performance

The design and fabrication of nanomaterials is a crucial issue in heterogeneous catalysis to achieve excellent performance. Traditionally, the main theme is to reduce the size of particles as small as possible mainly to increase the activity, so-called size-dependent catalytic chemistry. In recent years, the rapid developments in novel morphological and structural nanomaterials have enabled the fabrication of catalytic materials with exposing more reactive crystal planes, favoring a deep understanding of the active sites. Here, we highlight the recent progress in catalytic materials with unique performance caused by the morphology, by taking Co₃O₄ nanomaterials as an example. Firstly, we briefly summarize the important synthetic strategies and characteristics of morphology-controlled Co₃O₄ nanomaterials and their precursors like cobalt hydroxides, including zero- to two-dimensional and hierarchical nanostructures. Then, morphology/plane-dependent catalysis of these cobalt oxides is demonstrated, focusing on CH₄ combustion and CO oxidation in order to elaborate the intrinsic nature of morphology and surface plane. Finally, we outline our personal understanding and perspectives on the morphology-dependent nanocatalysis with metal and metal oxides. These morphology-controlled nanomaterials with more reactive crystal planes exposed are expected to be highly efficient for practical applications based on the deep understanding of the catalytically active sites.