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.
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.
Solvothermal reactions of 3-(3-methylpyridin-4-yl)benzoic
acid (Hmpba) with Mn(NO3)2 or Co(NO3)2 yielded isostructural porous coordination polymers,
[Mn(mpba)2]·guest (MCF-56, 1·g)
and [Co(mpba)2]·guest (MCF-57, 2·g), respectively. X-ray diffraction revealed that 1·g and 2·g possess similar one-dimensional ultramicroporous
channels, and guest-free [Mn(mpba)2] (1′) and [Co(mpba)2] (2′) possess significantly
and slightly contracted channels, respectively. Single-component C3H6/C3H8 adsorption isotherms
and computational simulations showed the typical nonporous-to-porous
structural transformations for 1′, in which C3H6 exhibits a significantly lower threshold pressure,
and the typical small-pore-to-large-pore structural transformations
for 2′, in which C3H6 exhibits
a slightly lower threshold pressure. Mixture column breakthrough experiments
showed that the C3H6/C3H8 separation performances of 2′ are obviously
better than those of 1′, because the latter cannot
adsorb C3H6 below the threshold pressure for
pore opening, and the pore opened by C3H6 can
adsorb C3H8.
Micro-sized spherical BiVO 4 photocatalysts composed of nanoparticles were synthesized by the sol-gel combustion method. The effects of citric acid and urea on the structural and morphological characteristics of samples were studied by X-ray diffraction, field emission scanning electron microscopy, N 2 adsorption and desorption and UV-Vis spectroscopy. The photocatalytic activity was evaluated by the photocatalytic degradation of rhodamine B under visible light. The results showed the sphere-shaped BiVO 4 sample to have excellent photocatalytic performance compared with the bulk sample prepared by solidstate reaction. This enhancement could be attributed to the special spherical morphology, which enhanced the absorption ability, increased the separation efficiency of photon-generated carriers and improved surface reaction sites for consumption of photon-generated carriers. Graphical Abstract Uniform micro-sized spherical BiVO 4 samples composed of nanoparticles were successfully synthesized by the sol-gel combustion method. The relationships between the morphologies and citric acid with urea contents were studied by using the field emission scanning electron microscopy (FE-SEM) technology.
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