Dattatray S. Dhawale

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 C(3)N(4) 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.

Fabrication and textural characterization of nanoporous carbon electrodes embedded with CuO nanoparticles for supercapacitors

Abstract We introduce a novel strategy of fabricating nanoporous carbons loaded with different amounts of CuO nanoparticles via a hard templating approach, using copper-containing mesoporous silica as the template and sucrose as the carbon source. The nature and dispersion of the CuO nanoparticles on the surface of the nanoporous carbons were investigated by x-ray diffraction (XRD), high-resolution scanning electron microscopy (HRSEM) and high-resolution transmission electron microscopy (HRTEM). XRD results reveal that nanoporous carbons with embedded CuO nanoparticles exhibit a well-ordered mesoporous structure, whereas the nitrogen adsorption measurements indicate the presence of excellent textural characteristics such as high surface area, large pore volume and uniform pore size distribution. The amount of CuO nanoparticles in the nanochannels of the nanoporous carbon could be controlled by simply varying the Si/Cu molar ratio of the mesoporous silica template. Morphological characterization by SEM and TEM reveals that high-quality CuO nanoparticles are distributed homogeneously within the nanoporous carbon framework. The supercapacitance behavior of the CuO-loaded nanoporous carbons was investigated. The material with a small amount of CuO in the mesochannels and high surface area affords a maximum specific capacitance of 300 F g-1 at a 20 mV s-1 scan rate in an aqueous electrolyte solution. A supercapacitor containing the CuO-loaded nanoporous carbon is highly stable and exhibits a long cycle life with 91% specific capacitance retained after 1000 cycles.

Highly ordered macro-mesoporous carbon nitride film for selective detection of acidic/basic molecules

Well-ordered meso-macroporous carbon nitride film fabricated via a simple and flexible template replication method by using the P123 block copolymer and polystyrene spheres as dual templates shows selective sensing performance for acetic acid but after treating the surface of the film with UV light and oxygen, the selectivity of sensing can be tuned for basic molecules.

Enhanced Supercapacitor Performance of N‐Doped Mesoporous Carbons Prepared from a Gelatin Biomolecule

Nitrogen-containing mesoporous carbon electrodes with tunable pore diameters for supercapacitor applications are synthesized by the nanocasting technique using a naturally abundant gelatin polymer as the single precursor for nitrogen and carbon.

A facile photo-induced synthesis of COOH functionalized meso-macroporous carbon films and their excellent sensing capability for aromatic amines

A simple photo-induced approach is developed for the preparation of COOH functionalized meso-macroporous carbon films with tunable pores without using any inorganic mesoporous silica templates, which show excellent sensing selectivity for aniline and the selectivity can be enhanced upon increasing COOH functional groups.

Fluorescent and Magnetic Mesoporous Hybrid Material: A Chemical and Biological Nanosensor for Hg2+ Ions

We introduce “sense, track and separate” approach for the removal of Hg2+ ion from aqueous media using highly ordered and magnetic mesoporous ferrosilicate nanocages functionalised with rhodamine fluorophore derivative. These functionalised materials offer both fluorescent and magnetic properties in a single system which help not only to selectively sense the Hg2+ ions with a high precision but also adsorb and separate a significant amount of Hg2+ ion in aqueous media. We demonstrate that the magnetic affinity of these materials, generated from the ultrafine γ-Fe2O3 nanoparticles present inside the nanochannels of the support, can efficiently be used as a fluorescent tag to sense the Hg2+ ions present in NIH3T3 fibroblasts live cells and to track the movement of the cells by external magnetic field monitored using confocal fluorescence microscopy. This simple approach of introducing multiple functions in the magnetic mesoporous materials raise the prospect of creating new advanced functional materials by fusing organic, inorganic and biomolecules to create advanced hybrid nanoporous materials which have a potential use not only for sensing and the separation of toxic metal ions but also for cell tracking in bio-separation and the drug delivery.

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−1, 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−1 at a power density of 0.07 kW kg−1.

Highly Selective Synthesis of Ortho‐Prenylated Phenols and Chromans by using a New Bimetallic CuAl‐KIT‐5 with a 3D‐Cage‐type Mesoporous Structure

A nice piece of KIT: The first synthesis of a new bimetallic 3D-cage-type mesoporous catalyst CuAl-KIT-5 and its remarkable performance for the highly selective synthesis of ortho-prenylated phenols and chromans is reported.

Mesoporous Gallosilicate with 3 D Architecture as a Robust Energy-Efficient Heterogeneous Catalyst for Diphenylmethane Production

Herein, we report the preparation of 3u2009D mesoporous gallosilicate with Ia3d symmetry (GaKIT‐6) and different gallium contents using Pluronic P123. The incorporation of gallium into the silica framework of KIT‐6 is difficult if the usual synthesis method of KIT‐6 is followed, because it requires a large amount of HCl in the synthesis mixture. Therefore, the amount of HCl in the synthesis mixture is reduced to suitably adjust the solution pH so as to incorporate a large amount of gallium into the silica framework of KIT‐6. The low‐angle powder XRD results confirm that all the samples demonstrate well‐ordered and a cubic 3u2009D structure with Ia3d symmetry. However, the wide‐angle XRD patterns show no peaks at the higher angle, which confirms the absence of gallium oxide nanoparticles in the nanochannels and the incorporation of gallium atoms into the silica framework. The nitrogen adsorption and electron microscopy studies reveal that the samples demonstrate excellent textural features with well‐ordered mesoporous structures having spherical morphology. The analysis of the solid‐state 29Siu2005MAS NMR spectra confirms that the gallium atoms are bonded tetragonally with the silica framework of KIT‐6. Furthermore, the catalytic performance of the materials has been investigated in the benzylation of benzene, with benzyl chloride as a benzylating agent. The catalytic activity of GaKIT‐6 increases with an increase in gallium content in the catalyst. GaKIT‐6 with a Si/Ga molar ratio of 7 demonstrates much better catalytic activity than do several reported 1u2009D and 2u2009D heteroatom‐incorporated mesoporous materials. In addition, the GaKIT‐6 catalyst is found to be highly active even at reaction temperatures as low as 313u2005K, which demonstrates a high benzyl chloride conversion and diphenylmethane selectivity. The catalytic activity of the GaKIT‐6 catalyst is retained even after the recyclability test, which confirms that the GaKIT‐6 catalyst is highly stable and can be used thrice without affecting its structural order.