Covalent organic frameworks (COFs) are of great potential as adsorbents owing to their tailorable functionalities, low density and high porosity. However, their intrinsically stacked two-dimensional (2D) structure limits the full use of their complete surface for sorption, especially the internal pores. The construction of ultrathin COFs could increase the exposure of active sites to the targeted molecules in a pollutant environment. Herein, an ultrathin COF with a uniform thickness of ca. 2 nm is prepared employing graphene as the surface template. The resulting hybrid aerogel with an ultralow density (7.1 mg cm À 3 ) exhibits the ability to remove organic dye molecules of different sizes with high efficiency. The three-dimensional (3D) macroporous structure and well-exposed adsorption sites permit rapid diffusion of solution and efficient adsorption of organic pollutants, thereby, greatly contributing to its enhanced uptake capacity. This work highlights the effect of COF layer thickness on adsorption performance.
New routes to porous
materials can help lower production costs,
improve sustainability, and broaden design options. Here, we use a
selection of organic acids as catalysts in the synthesis of organic
hyper-cross-linked polymers from benzyl methyl ether compounds. This
approach provides a new route to metal-free porous organic polymers
and addresses one of the largest setbacks of hyper-cross-linked polymers
by allowing the simple recovery and recycling of a nonmetallic catalyst.
By use of p-toluenesulfonic acid, a solid at room
temperature, catalyst recovery rates of >80% were easily achieved.
The catalyst was then reused as recovered in the further production
of hyper-cross-linked polymers. Three rounds of catalyst recycling
are demonstrated on two different aromatic systems, with no apparent
detriment to the chemical or textural properties of the resulting
networks.
Non-noble mixed metal oxides are promising electrocatalysts for water splitting reactions in alkaline media. The synthesis of complex mixed metal oxides with the desired composition is challenging due to the formation of phase impurities when synthesis is performed via classical approaches. In this work, we applied the nanocasting technique combined with low-temperature calcination (200 °C) in a quasi-sealed container to obtain highly ordered mesoporous mixed metal (Mn/Fe/Ni/Co) oxides. This procedure provides electrocatalysts with distinctive physicochemical characteristics and improved electrocatalytic properties. Partial Ni substitution in Ni 0.5 Co 2.5 O 4 by Fe and Mn in combination with the highly ordered mesostructure offers a large number of active sites and enhances the performance of the catalyst toward the oxygen evolution reaction (OER) in the alkaline electrolyte. The Mn/Fe/Ni/Co oxide calcined at 200 °C outperforms all other synthesized oxides (current density of 262 mA cm −2 at 1.7 V versus RHE and overpotential of 363 mV at 10 mA cm −2 ) due to synergistic effects. Moreover, this catalyst exhibits significantly higher activity compared to the oxide of identical composition calcined at higher temperature. The results presented in this work show that tuning the synthesis conditions and composition of mixed metal oxides is a simple way to tailor their surface chemistry, mesoporous structure, and catalytic performance for the OER.
An ultrathin covalent organic framework (COF) was constructed homogeneously on the surface of a graphene template via a facile hydrothermal method, as reported by Freddy Kleitz and co‐workers in their Research Article (e202206564). Benefitting from the maximum exposure of active sites and sufficient interaction with target water pollutants, the ultrathin COF could effectively shorten the equilibrium time and increase the adsorption capacity for the removal of organic dyes with various sizes.
To facilitate the creation of novel nanocarrier systems targeting the intestinal microbiome, inulin‐conjugated mesoporous silica nanoparticles (MSNs) are described herein for the first time. Surface functionalization is achieved on either hydrophilic or hydrophobic mesoporous nanoparticles using different conjugation methods. The targeting performance of the resulting materials is assessed and compared upon incubation with human stool. It appears that amide formation is the most favorable coupling method on hydrophilic MSNs to achieve the desired bioconjugate. Remarkably, high affinity of gut bacteria to the conjugated particles can be obtained, paving the way to novel targeted drug delivery systems.
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