Single atom catalysts (SACs) are receiving increasing interests due to their high theoretical catalytic efficiency and intriguing physiochemical properties. However, most of the synthetic methodologies involve high-temperature treatment. This usually leads to limited control over the spatial distribution of metal sites and collapse of porous network that result in limited active site exposure. A strategy to construct SAC by using a covalent organic framework as the precursor is reported in this study. The as-prepared catalyst is mainly composed of standing carbon layers with the presence of edge-site hosted metal single atoms. Such structure configuration not only allows full site exposure but also endows the metal site with high intrinsic activity. With a trace amount of cobalt loading (0.17 wt%), the nanorice-shaped catalyst displays promising electrochemical activities toward catalyzing the oxygen reduction reaction in both alkaline and acidic medium. An ultrahigh mass activity of 838 A gCo -1 at 0.9 V is achieved in the acidic electrolyte. This work suggests a new route to design SACs based on covalent organic framework for energy storage and conversion devices.
Keywords: covalent organic frameworks (COFs); oxygen reduction reaction (ORR); single atom catalysts (SACs); standing carbon.
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