Single‐Layer 2D Ni−BDC MOF Obtained in Supercritical CO2‐Assisted Aqueous Solution

Abstract The development of an efficient strategy for fabricating two‐dimensional metal‐organic framework (MOF) nanosheets with high yield and high stability is desirable. Herein, we demonstrate for the first time that large, single‐layer 2D nickel‐benzene dicarboxylate (Ni−BDC) MOF nanosheets can be fabricated with the assistance of supercritical (SC) CO 2 in a pure aqueous system. Detailed experimental evidence reveals that the SC CO 2 molecule can exchange with the lattice‐coordinated H 2 O molecules, side‐on coordinate with the metal Ni 1 sites on the Ni−BDC surface, and finally break the interlayer hydrogen bond to exfoliate the bulk Ni−BDC into a 2D MOF. More importantly, a thin SC CO 2 layer building up at the water−Ni−BDC interfaces can transform the pristine hydrophilic interface into a super‐hydrophobic one. This super‐hydrophobic layer at the water‐MOF interface can effectively prevent dissociation, thus promoting the stability of Ni−BDC in aqueous system.