POM@MOF hybrids : synthesis and applications

The hybrid materials that are created by supporting or incorporating polyoxometalates (POMs) into/onto metal–organic frameworks (MOFs) have a unique set of properties. They combine the strong acidity, oxygen-rich surface, and redox capability of POMs, while overcoming their drawbacks, such as difficult handling, a low surface area, and a high solubility. MOFs are ideal hosts because of their high surface area, long-range ordered structure, and high tunability in terms of the pore size and channels. In some cases, MOFs add an extra dimension to the functionality of hybrids. This review summarizes the recent developments in the field of POM@MOF hybrids. The most common applied synthesis strategies are discussed, together with major applications, such as their use in catalysis (organocatalysis, electrocatalysis, and photocatalysis). The more than 100 papers on this topic have been systematically summarized in a handy table, which covers almost all of the work conducted in this field up to now

Promotional effect of N-functionality on the catalytic performance of heterogeneous Ru catalysts : enhanced catalytic activity of Ru@CTF vs Ru@UiO-67 for aerobic oxidation of alcohols

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Immobilization of a new (salen) molybdenum(VI) complex onto the ion-exchangeable polysiloxane as a heterogeneous epoxidation catalyst

In this study, a new recoverable catalyst for the epoxidation of olefins was developed using a layered polysiloxane as a support for immobilizing  (salen) molybdenum(VI) complex by electrostatic interaction between the surface of the solid support and the electrically charged molybdenum complex. Characterization of the heterogeneous catalyst by Fourier transform infrared, XRD,1H NMR, and atomic absorption spectroscopes as well as thermogravimetric and CHN elemental analyses confirmed successful immobilization of the (salen) molybdenum(VI) complex to the support. The prepared catalyst catalyzed the epoxidation of olefins efficiently. The effect of different factors on the epoxidation of cyclooctene was investigated. Reaction conditions including reaction temperature, solvent type, substrate amount, catalyst amount and oxidant  amount  were systematically optimized in order to achieve the highest conversion of cyclooctene. Various other olefins showed high catalytic activity and selectivity under the optimal reaction conditions. Regenerability test demonstrated that the catalyst can be recycled for at least five times without leaching of molybdenum. Moreover, the catalyst showed good stability under the reaction conditions as determined by FT-IR and ICP-OES analyses

Covalent triazine framework/carbon nanotube hybrids enabling selective reduction of CO2 to CO at low overpotential

Electrochemical reduction of CO2 provides a way to generate base chemicals from an abundant C1-source under mild conditions, whilst at the same time mitigating CO2 emissions. In this work, a novel class of tailorable, porous electrocatalysts for this process is proposed. Covalent triazine frameworks (CTFs) are grown in situ onto functionalized multiwalled carbon nanotubes. Hydroxyl groups decorating the surface of the multiwalled carbon nanotubes facilitate intimate contact between the carbon nanotubes and CTF, thus promoting efficient electron transfer. The novel hybrid materials generate CO with a faradaic efficiency up to 81% at an overpotential of 380 mV. The selectivity of the electrocatalysts could be linked to the amount of nitrogen present within the framework