Two-Dimensional Cr(III)-Based Metal-Organic Framework with Ultrahigh Stability and Superprotonic Conductivity Enabled
Ke Wang1, Shaoan Wang2, Zhiwen Shi2
1Beijing Key Laboratory for Catalysis and Separation, Department of Chemical Engineering, College of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China.
Abstract:
Proton-conducting two-dimensional metal-organic frameworks (2D MOFs) are attractive solid electrolytes for electrochemical technologies, yet simultaneously achieving superprotonic conductivity and robustness remains highly challenging. Here, we report TGU-80(Cr), a 2D Cr(III)-MOF synthesized via a solvent-free route enabled by a stereochemistry-guided sulfonate-linker design. Three-dimensional electron diffraction reveals a bidentate sulfonate coordination motif that preserves one noncoordinating O atom on every sulfonate, furnishing O-dense nanochannels that favor hydration and hydrogen-bonding networks. These channels support fast proton transport, delivering a conductivity up to 5.61 × 10-2 S cm-1 at 90 °C and 100% RH, which, to the best of our knowledge, is among the highest reported for additive-free proton-conducting 2D MOFs. Owing to inert Cr-O bonds and extensive interlayer hydrogen bonding, TGU-80(Cr) also exhibits exceptional chemical stability from strongly acidic media to 1 M NaOH. This work not only establishes an unprecedented 2D Cr-MOF that combines ultrahigh stability with superprotonic conductivity but also expands the design and synthesis strategies for low-dimensional reticular materials via the green solvent-free route.
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