Two-dimensional (2D) materials and ultrathin nanosheets are advantageous for elevating the catalysis performance and elucidating the catalysis mechanism of heterogeneous catalysts, but they are mostly restricted to inorganic or organic materials based on covalent bonds. We report an electrochemical/chemical exfoliation strategy for synthesizing metal-organic 2D materials based on coordination bonds. A catechol functionalized ligand is used as the redox active pillar to construct a pillared-layer framework. When the 3D pillared-layer MOF serves as an electrocatalyst for water oxidation (pH 13), the pillar ligands can be oxidized in situ and removed. The remaining ultrathin (2 nm) nanosheets of the metal-organic layers are an efficient catalyst with overpotentials as low as 211 mV at 10 mA cm and a turnover frequency as high as 30 s at an overpotential of 300 mV.

The changeable molecular dynamics of flexible polar cations in the variable confined space between inorganic chains brings about a new type of two-step nonlinear optical (NLO) switch with genuine "off-on-off" second harmonic generation (SHG) conversion between one NLO-active state and two NLO-inactive states.

Efficient adsorptive separation of propylene/propane (C 3 H 6 /C 3 H 8 )i sh ighly desired and challenging.K nown strategies focus on either the thermodynamic or the kinetic mechanism. Here,w er eport an interesting reactivity of am etal-organic framework that improves thermodynamic and kinetic adsorption selectivity simultaneously.W hen the metal-organic framework is heated under oxygen flow, half of the soft methylene bridges of the organic ligands are selectively oxidized to form the more polar and rigid carbonyl bridges. Mixture breakthrough experiments showed drastic increase of C 3 H 6 /C 3 H 8 selectivity from 1.5 to 15. Forc omparison, the C 3 H 6 /C 3 H 8 selectivities of the best-performing metal-organic frameworks Co-MOF-74 and KAUST-7 were experimentally determined to be 6.5 and 12, respectively.G as adsorption isotherms/kinetics,s ingle-crystal X-ray diffraction, and computational simulations revealed that the oxidation gives additional guest recognition sites,w hich improve thermodynamic selectivity,a nd reduces the framework flexibility,w hich generate kinetic selectivity.

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Tw o-dimensional (2D) materials and ultrathin nanosheets are advantageous for elevating the catalysis performance and elucidating the catalysis mechanism of heterogeneous catalysts,but they are mostly restricted to inorganic or organic materials based on covalent bonds.W er eport an electrochemical/chemical exfoliation strategy for synthesizing metal-organic 2D materials based on coordination bonds.A catechol functionalizedligand is used as the redox active pillar to construct apillared-layer framework. When the 3D pillaredlayer MOF serves as an electrocatalyst for water oxidation (pH 13), the pillar ligands can be oxidized in situ and removed. The remaining ultrathin (2 nm) nanosheets of the metalorganic layers are an efficient catalyst with overpotentials as low as 211 mV at 10 mA cm À2 and aturnover frequency as high as 30 s À1 at an overpotential of 300 mV.