Polarity‐Directed Synthesis of an Exfoliable 2D Polyoxometalate‐Based Metal‐Organic Framework for Noble Metal‐Free Alkyne Transfer Semi‐Hydrogenation

ABSTRACT Two‐dimensional polyoxometalate‐based metal–organic frameworks (2D POMOFs) hold great promise for catalysis, yet their directed synthesis and facile exfoliation remain challenging. Herein, we report the rational assembly of an exfoliable 2D POMOF, H 5 [(Co(H 2 O) 2 ) 2 (C 18 H 12 N 6 ) 4 (P 2 W 15 Ta 3 O 62 )]·18H 2 O ( 1 ), directed by the nonuniform charge distribution within the POM. The unique layered structure enables a multi‐step morphological control strategy: hydrothermal synthesis gives access to high‐quality single crystals, while a scalable bulk synthesis allows the rapid production of nanobelts, which can subsequently be exfoliated into ultrathin bilayer nanosheets via a liquid‐nitrogen treatment, or even monolayer nanosheets via solvent‐assisted sonication. The bilayer nanosheets exhibit high catalytic activity and selectivity for alkyne transfer semi‐hydrogenation, outperforming the corresponding bulk and nanocrystalline counterparts and rivaling noble‐metal‐based catalysts. This work establishes charge‐asymmetric POM‐directed synthesis as a viable strategy for creating defined 2D materials.