CO₂ controls the oriented growth of metal-organic framework with highly accessible active sites

The production of 2D metal-organic frameworks (MOFs) with highly exposed active surfaces is of great importance for catalysis. Here we demonstrate the formation of MOF nanosheets by utilizing CO₂ as a capping agent to control the oriented growth of MOF. This strategy has many advantages over the conventional methods. For example, it is template-free and proceeds at mild temperature (35 °C), CO₂ can be easily removed by depressurization, and the properties of the MOF nanosheets can be well adjusted by changing CO₂ pressure. Such a simple, rapid, efficient and adjustable route produces MOF nanosheets with ultrathin thickness (∼10 nm), small lateral size (∼100 nm) and abundant unsaturated coordination metal sites on surfaces. Owing to these unique features, the as-synthesized MOF nanosheets exhibit superior activity for catalyzing the oxidation reactions of alcohols.