Synthesis of nitrogen-rich mesoporous carbon nitride with tunable pores, band gaps and nitrogen content from a single aminoguanidine precursor

Highly ordered mesoporous carbon nitride (CN) with an extremely high nitrogen content and tunable pore diameters was synthesized by using a new precursor with a high nitrogen content, aminoguanidine hydrochloride and mesoporous silica SBA-15 with different pore diameters as hard templates. Surprisingly, the N/C ratio of the prepared mesoporous CN (MCN-4: 1.80) was considerably higher than that of the theoretically predicted CN nanostructures (1.33). This is mainly due to the fact that the CN precursor easily undergoes polymerization at high temperature and affords a highly stable polymer composed of a diamino-s-tetrazine moiety with a six-membered aromatic ring containing six nitrogen atoms that are linked trigonally with the nitrogen atoms. The obtained materials were thoroughly characterized by means of XRD, nitrogen adsorption, high resolution TEM, electron energy loss spectra, high resolution SEM, X-ray photoelectron spectroscopy, FTIR, and C, N, O, and S analysis. The results show that the MCN-4 materials possess a well-ordered mesoporous structure similar to SBA-15 with a high specific surface area and tunable band gap in the range of 2.25-2.49 eV. Interestingly, the pore diameter of the materials can be finely tuned from 3.1-5.8 nm by increasing the pore diameter of the hard-template SBA-15. The reaction temperature plays a critical role for the formation of MCN, and we found that 400 °C is the best condition to obtain MCN-4 with a high nitrogen content. We have further investigated the catalytic application of the MCN-4 materials towards Friedel-Crafts hexanoylation of benzene and compared the results with the mesoporous CN with less nitrogen content (MCN-1) and nonporous CN. Among the materials studied, MCN-4 showed the highest activity, affording a high yield of hexanophenone within a few hours, which is mainly due to the presence of free amine groups on the wall structure of MCN-4

3D Nanoporous FeAl-KIT-5 with a cage type pore structure: a highly efficient and stable catalyst for hydroarylation of styrene and arylacetylenes

A novel bimetallic nanoporous FeAl-KIT-5 catalyst with a cage type porous structure and a high surface area has been prepared for the hydroarylation of styrene and arylacetylenes to afford 1,1-diarylalkanes and 1,1-diarylalkenes, respectively. The catalyst was found to be highly active, and selective, affording a high yield of substituted alkanes and alkenes. The catalyst also showed much higher activity as compared to those of other nanoporous catalysts such as AlSBA-15, AlKIT-5, and FeKIT-5, and can be reused several times without much loss of its activity

A single-step synthesis of electroactive mesoporous ProDOT-silica structures

The single-step preparation of highly ordered mesoporous silica hybrid nanocomposites with conjugated polymers was explored using a novel cationic 3,4-propylenedioxythiophene (ProDOT) surfactant (PrS). The method does not require high-temperature calcination or a washing procedure. The combination of self-assembly of the silica surfactant and in situ polymerization of the ProDOT tail is responsible for creation of the mesoporosity with ultralarge pores, large pore volume, and electroactivity. As this novel material exhibits excellent textural parameters together with electrical conductivity, we believe that this could find potential applications in various fields. This novel concept of creating mesoporosity without a calcination process is a significant breakthrough in the field of mesoporous materials and the method can be further generalized as a rational preparation of various mesoporous hybrid materials having different structures and pore diameters

Mesoporous aluminosilicate nanocage-catalyzed three-component coupling reaction: an expedient synthesis of alpha-aminophosphonates

Here we demonstrate for the first time the synthesis of α-aminophosphonates through the three-component coupling reaction of aldehydes, amines, and diethyl phosphite by using highly acidic 3D mesoporous aluminosilicate nanocage catalyst, which gave excellent yield with a high selectivity in a short reaction time due to its high acidity, 3D pores, and a huge space in the nanocages

Facile synthesis and basic catalytic application of 3D mesoporous carbon nitride with a controllable bimodal distribution

Here we demonstrate a facile synthesis of 3D mesoporous carbon nitride with Ia3d symmetry (MCN-6) using mesoporous silica KIT-6 with 3D porous structure and different pore diameters as hard templates, and ethylenediamine and carbon tetrachloride as the sources for N and C, and C, respectively. The obtained materials possess bimodal pores that can be controlled with a simple adjustment of the pore diameter of the KIT-6 templates. The lower angle powder X-ray diffraction (XRD) patterns and high resolution transmission electron microscope (HRTEM) images confirm that the MCN-6 materials possess a well-ordered mesoporous 3D structure with a highly interwoven and a branched pore structure. The textural parameters such as the specific surface areas and specific pore volumes of the materials can also be controlled by tuning the pore diameter of the hard template. The specific surface area and the specific pore volume of the samples increase with increasing the pore diameter of the hard template. The C/N ratio of the MCN-6 is ca. 4.3 which is similar to that obtained for MCN-1 prepared from SBA-15 as template. FT-IR and XPS spectroscopy results reveal that samples contain a CN network with a lot of free NH groups which are originated from ethylenediamine and can offer the basic sites. The temperature programmed desorption of CO confirms that the samples are highly basic and the basicity of the sample is 0.195 mmol of CO per g which is higher than that of MCN-1 (0.14 mmol of CO per g). We tested the performance of MCN-6 materials in the base-catalyzed Knoevenagel condensation of benzaldehyde and malononitrile. The catalysts exhibit excellent activity and afford a high yield of the corresponding α,β-unsaturated nitrile in a short reaction time even at room temperature. In addition, catalysts are highly stable and can be recyclable several times without affecting their activity

Mesoporous and hexagonally ordered CuAl-SBA-15-catalyzed tandem C-C and C-O bond formation between phenols and allylic alcohols

A novel mesoporous catalyst, CuAl-SBA-15, with a hexagonally ordered porous structure prepared via a soft-templating approach in a highly acidic medium is used for tandem C-C and C-O bond formation between phenols and allylic alcohols to afford a variety of dihydrobenzopyrans in good yields. The catalyst is also found to be highly active for the synthesis of vitamin E and can be recycled several times without significant loss of its activity

Cobalt oxide functionalized nanoporous carbon electrodes and their excellent supercapacitive performance

Nanoporous carbon (CMK-3-150) functionalized with different amounts of cobalt oxide (CoO) nanoparticles was synthesized by an incipient wetness impregnation technique for supercapacitor application. The characterization results reveal that the specific surface area and pore volume of the CoO functionalized CMK-3-150 marginally decrease upon increasing the amount of the CoO whereas the pore diameter and the structure of the CMK-3-150 were not affected even after the functionalization. The electrochemical measurements show that the specific capacitance of the electrodes was enhanced after the functionalization with CoO. Among the electrodes studied, CMK-3-150 functionalized with 15 wt% CoO shows an excellent cycling stability and specific capacitance of 331 F g, which is ca. two times higher than that of the pure nanoporous carbon. This enhanced performance is due to the combined contribution of electrical double layer capacitance and pseudocapacitance. A symmetric supercapacitor device based on the CMK-3-150-15Co electrode gives the maximum energy density of 29.67 W h kg at a power density of 0.07 kW kg. This journal i

Post-synthetic functionalization of mesoporous carbon electrodes with copper oxide nanoparticles for supercapacitor application

Mesoporous carbon electrodes have been decorated with different contents of Cu/CuO nanoparticles via post-synthetic approach and successfully used for supercapacitor application. The N adsorption results reveal that all the functionalized materials exhibit a well-ordered mesoporous structure with excellent textural characteristics whereas the XRD results demonstrate that the structure of the mesoporous carbon support is retained even after the functionalization process. The HRSEM and HRTEM images display that the copper oxides are highly dispersed along the nanochannels of the mesoporous carbon support which are critical for the supercapacitor application. The electrochemical performance of Cu/CuO nanoparticles functionalized mesoporous carbon with tunable etc. pore structures is investigated by cyclic voltammetry, charge/discharge test and electrochemical impedance spectroscopy. Interestingly, as the pore diameter of the support increases, electrochemical performance is also increased and a maximum specific capacitance of 380 F g at a current density of 1 mA cm is achieved for CMK-3-150 loaded with 20 wt% of the Cu/CuO nanoparticles. The excellent electrochemical performance of the functionalized mesoporous carbon electrodes are attributed to the combined effect of electrical double layer and pseudo capacitance generated by the support with excellent textural parameters and the Cu/CuO nanoparticles, respectively. Crown Copyrigh