Exfoliation of 2D Metal‐Organic Frameworks: toward Advanced Scalable Materials for Optical Sensing

Abstract Two‐dimensional metal‐organic frameworks (MOFs) occupy a special place among the large family of functional 2D materials. Even at a monolayer level, 2D MOFs exhibit unique sensing, separation, catalytic, electronic, and conductive properties due to the combination of porosity and organo‐inorganic nature. However, lab‐to‐fab transfer for 2D MOF layers faces the challenge of their scalability, limited by weak interactions between the organic and inorganic building blocks. Here, comparing three top‐down approaches to fabricate 2D MOF layers (sonication, freeze‐thaw, and mechanical exfoliation), The technological criteria have established for creation of the layers of the thickness up to 1 nm with a record aspect ratio up to 2*10^4:1. The freezing‐thaw and mechanical exfoliation are the most optimal approaches; wherein the rate and manufacturability of the mechanical exfoliation rivaling the greatest scalability of 2D MOF layers obtained by freezing‐thaw (21300:1 vs 1330:1 aspect ratio), leaving the sonication approach behind (with a record 900:1 aspect ratio) have discovered. The high quality 2D MOF layers with a record aspect ratio demonstrate unique optical sensitivity to solvents of a varied polarity, which opens the way to fabricate scalable and freestanding 2D MOF‐based atomically thin chemo‐optical sensors by industry‐oriented approach.