An effective fluorescent probe (mSiO-N-CDs) was prepared by embedding N-CDs into mesoporous silica via a simple one-pot hydrothermal reaction and applied to the detection of dopamine (DA). Mesoporous silica not only provided a skeleton to prevent the aggregation of N-CDs but also a medium for the centrifugal collection of N-CDs, avoiding the need for dialysis and freeze-drying. The formation process, phase composition, morphology, and luminescence properties of the composite were studied in detail.
View Article and Find Full Text PDFEffective contact and collision between reactants and active sites are essential for heterogeneous catalysis. Herein, we investigated molecular diffusion in more than 200 kinds of zeolites, and an intriguing "diffusive skin effect" was observed, whereby molecules migrated along the pore walls of zeolites (, diffusion trajectories) because of the effect of the guest-host interaction and diffusion barrier. Furthermore, it was found that such a "diffusive skin effect" of zeolites would strongly promote the contacts and collisions between reactants and active sites in the reaction process, which might effectively promote the zeolite-catalyzed performance.
View Article and Find Full Text PDFMagnetic carbon-based composites are the most attractive candidates for electromagnetic (EM) absorption because they can terminate the propagation of surplus EM waves in space by interacting with both electric and magnetic branches. Metal-organic frameworks (MOFs) have demonstrated their great potential as sacrificing precursors of magnetic metals/carbon composites, because they provide a good platform to achieve high dispersion of magnetic nanoparticles in carbon matrix. Nevertheless, the chemical composition and microstructure of these composites are always highly dependent on their precursors and cannot promise an optimal EM state favorable for EM absorption, which more or less discount the superiority of MOFs-derived strategy.
View Article and Find Full Text PDFLithium-sulfur (Li-S) batteries are one of the most promising candidates for next-generation energy storage systems because of their high theoretical energy density. However, the shuttling behavior and sluggish conversion kinetics of lithium polysulfides (LiPSs) limit their practical application. Herein, B-doped MoS nanosheets are synthesized on carbon nanotubes (denoted as CNT@MoS-B) to function as catalysts to boost the performance of Li-S batteries.
View Article and Find Full Text PDFPolysulfide shuttling and sluggish sulfur redox kinetics hinder the cyclability and rate capability of lithium-sulfur (Li-S) batteries. The intrinsic redox kinetics of sulfur cathodes strongly depends on the interaction between catalysts and sulfur species. Herein, N-doped CoTe is proposed as an effective dual-anchoring electrocatalyst, which can simultaneously bind Li and S atoms in lithium polysulfides via ionic Te-Li/N-Li bonding and coordinate covalent Co-S bonding.
View Article and Find Full Text PDFMicro-/nanostructured materials can control the diffraction and propagation of light, thereby providing new optical properties that can be exploited to enhance photocatalytic processes. In this work, a series of the cauliflower-like MoS/CdS hybrid micro-/nanostructures is synthesized. These structures contain numerous cracks and pores that can enhance the absorption and utilization of light as well as shorten the distance for transferring photogenerated electrons to the catalyst surface.
View Article and Find Full Text PDFN-doped carbon materials are well known as promising metal-free catalysts and applied in innumerable industrial synthetics. However, most of the N-doped carbon materials obtained by conventional synthetic means exhibit generally low mesoporosity, and their reported pore volumes reached only 1-3 cm g, which greatly limits their further industrial application in heterogeneous catalysis. Especially for oxidation reaction of alkylbenzenes, this type of reaction is almost always accompanied by many different byproducts, while the reaction activity and selectivity are mainly affected by mesoporosity of catalysts.
View Article and Find Full Text PDFCarbon materials with multilevel structural features are showing great potentials in electromagnetic (EM) pollution precaution. With ZIF-67 microcubes as a self-sacrificing precursor, hierarchical carbon microcubes with micro/mesoporous shells and hollow cavities have been successfully fabricated with the assistance of rigid SiO coating layers. It is found that the SiO layer can effectively counteract the inward shrinkage of organic frameworks during high-temperature pyrolysis due to intensive interfacial interaction.
View Article and Find Full Text PDFACS Appl Mater Interfaces
August 2020
Metal-organic framework (MOF)-supported macroscale resin catalysts, IRA900(OH)-MIL-101(Al)-NH ( means the concentration of NaOH), with spatially isolated antagonistic acid-base active sites were successfully synthesized through a novel strategy by ion exchange and in situ solvothermal methods. The hierarchical pore system of the as-prepared catalysts effectively promotes the mass transfer and contacts with catalytic active centers during the organic reactions. Therefore, the environmentally friendly catalysts exhibit excellent superior activity and stability in one-pot deacetalization-Knoevenagel condensation reaction, and the yield by optimal IRA900(0.
View Article and Find Full Text PDFIn this work, three organosilica precursors functionalized with carbamate moieties were synthesized by condensing of 3-isocyanatopropyltriethoxysilane and coupling regents of either hydroquinone (HQ), bisphenol A (BPA), or 1,1'-bi-2-naphthol (BN). These organosilica precursors were covalently bonded in the framework of periodic mesoporous organosilicas by co-condensation and hydrolysis with tetraethyl orthosilicate (TEOS) under hydrothermal treatment. The compositions and physical properties were characterized with FTIR, XRD, thermogravimetric/differential thermal analysis (TG/DTA), Si NMR, C NMR spectroscopies, SEM, TEM, and BET technologies.
View Article and Find Full Text PDFA novel photocatalyst of mesoporous graphitic carbon nitride (g-CN) co-doped with Co and Mo (Co/Mo-MCN) has been one-pot synthesized via a simple template-free method; cobalt chloride and molybdenum disulfide were used as the Co and Mo sources, respectively. The characterization results evidently indicate that molybdenum disulfide functions as Mo sources to incorporate Mo atoms in the framework of g-CN and as a catalyst for promoting the decomposition of g-CN, resulting in the creation of mesopores. The obtained Co/Mo-MCN exhibited a significant enhancement of the photocatalytic activity in H evolution (8.
View Article and Find Full Text PDFA series of multiscale cementite/iron/porous carbon (CIPC-T) composites with extremely low nitrogen content and millimeter-size spherical morphology were prepared by simple carbothermal pyrolysis of resin spheres exchanged with ferric oxalate anions. CIPC-T materials are composed of highly disperse core-shell-structured Fe C/Fe@graphitic carbon (CI@GC) nanoparticles embedded in a porous amorphous carbon framework. A mechanism for the formation of the composites is proposed on the basis of the results of XRD, SEM, TEM, and thermogravimetric analysis.
View Article and Find Full Text PDFHybrid molecularly imprinted mesoporous silicas were synthesized by co-condensation of tetraethoxysilane and functional organosilica precursors of HQP and BPAP, in which hydroquinone (HQ) and bisphenol A (BPA) were linked as imprinting molecules. Owing to the existence of a thermally reversible covalent bond of carbamate (-NH-COO-), the imprinting molecules could be eliminated under thermal treatment and molecularly imprinted cavities were formed in the framework wall. All of these materials were used to catalyze heterogeneous Knoevenagel reactions and proved to exhibit higher catalytic conversion and turnover frequency (TOF) number compared with the materials with imprinting molecules, which is attributed to the presence of amino groups with higher basicity and molecularly imprinted cavities.
View Article and Find Full Text PDFNitrogen doped carbon materials as electrodes of supercapacitors have attracted abundant attention. Herein, we demonstrated a method to synthesize N-doped macroporous carbon materials (NMC) with continuous channels and large size pores carbonized from polyaniline using multiporous silica beads as sacrificial templates to act as electrode materials in supercapacitors. By the nice carbonized process, i.
View Article and Find Full Text PDFMesoporous TiO/Carbon beads have been prepared via a facile impregnation-carbonization approach, in which a porous anion-exchange resin and KTiO(CO) were used as hard carbon and titanium source, respectively. Characterization results reveal that the self-assembled composites have disordered mesostructure, uniform mesopores, large pore volumes, and high surface areas. The mesopore walls are composed of amorphous carbon, well-dispersed and confined anatase or rutile nanoparticles.
View Article and Find Full Text PDFCarbon nanotubes (CNTs) were covalently functionalized via 1,3-dipolar cycloaddition reaction under microwave conditions. The functionalized CNTs were characterized by thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), N2 adsorption isotherms and Raman spectroscopy. The surface concentration of phenolic hydroxyl groups on the surface of CNTs was adjusted by varying the reaction temperature.
View Article and Find Full Text PDFNanoparticular MRI contrast agents are rapidly becoming suitable for use in clinical diagnosis. An ideal nanoparticular contrast agent should be endowed with high relaxivity, biocompatibility, proper plasma retention time, and tissue-specific or tumor-targeting imaging. Herein we introduce PEGylated KMnF3 nanoparticles as a new type of T1 contrast agent.
View Article and Find Full Text PDFPorous γ-Fe2O3-polymer composites were synthesized by a novel one-pot surfactant-free hydrothermal approach. The γ-Fe2O3-polymer composites consisting of 3.5 nm γ-Fe2O3 nanoparticles and porous polymers exhibited high catalytic activity and recycling performance in the reduction of nitroarenes.
View Article and Find Full Text PDFA rapid quantitative method of ultra performance liquid chromatography (UPLC) has been developed for the analysis of 17 amino acids in fish eggs from Acipenser schrenckii, Huso dauricus and Acipenser ruthenus. The analytes were hydrolyzed with 6 0 mol/L HCI. The extraction solution was concentrated under low pressure and neutralized with NaOH solution before derivatization with 6-aminoquinolyl-N-hydroxy-succinimidyl carbamate (AQC) as derivatization agent in borate buffer solution (pH 8.
View Article and Find Full Text PDFA rapid, sensitive, and reliable ultra-performance liquid chromatography (UPLC) coupled with photodiode array detection method was developed for the amino acid analysis of Amur sturgeon (Acipenser schrenckii Brandt). The method uses minimal sample volume and automated online precolumn derivitization of amino acids with fluorescent 6-aminoquinolyl-carbamyl reagent. The chromatographic separation was achieved by UPLC, which used a column with 1.
View Article and Find Full Text PDFWe report a new type of dual modal nanoprobe to combine optical and magnetic resonance bioimaging. A simple reverse microemulsion method and coating process was introduced to synthesize silica-coated Gd(2)(CO(3))(3):Tb nanoparticles, and the particles, with an average diameter of 16 nm, can be dispersed in water. As in vitro cell imaging of the nanoprobe shows, the nanoprobe accomplishes delivery to gastric SGC7901 cancer cells successfully in a short time, as well as NCI-H460 lung cancer cells.
View Article and Find Full Text PDFThree supramolecular architectures based on alpha-Keggin-type polyoxometalates have been synthesized hydrothermally, and their structures have been characterized by elemental analyses, infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and single crystal X-ray diffraction structure analyses. [Ni(enMe)(2)(H(2)O)(2)](2)[Ni(enMe)(2)PW(VI)(9)W(V)(3)O(40)] x H(2)O (1) (enMe = 1,2'-propanediamine) exhibits a novel 2-D supramolecular sinusoidal layer through the interactions between transition metal complexes and 1-D covalent chains which are constructed from alpha-Keggin units bridged by transition metal complexes. [Ni(enMe)(2)](4){[Ni(enMe)(2)][Ni(enMe)(2)(H(2)O)AsW(VI)(6)W(V)(4)V(IV)(4)O(42)](2)} x 6 H(2)O (2), representing a 3-D supramolecular framework with 1-D channels, contains the first example of a tungstate dimer with inorganic-organic composite surfaces built up from [Ni(enMe)(2)](2+) cation bridges and bi-capped alpha-Keggin polyoxometalate building blocks supporting the transition metal complex.
View Article and Find Full Text PDFThe purely inorganic microporous compound [H(3)O][Fe(4)F(4)(AsO(4))(3)] x 3 H(2)O (1), which contains novel cubane-like Fe(4)F(4) cages, exhibiting a 3D configuration with channels of dimensions 8 A x 8 A running along the [001], [010], and [100] directions, presents antiferromagnetic interactions.
View Article and Find Full Text PDFActa Crystallogr Sect E Struct Rep Online
January 2008
The title compound, [Cu(2)V(4)O(12)(C(10)H(8)N(2))(2)](n), shows a two-dimensional copper-vanadate layer composed of eight-membered rings, each containing four corner-sharing VO(4) tetra-hedra; these are linked through six penta-coordinated Cu(II) atoms with the 2,2'-bipyridine ligands attached and pointing above and below the plane of the layer. The Cu atom is coordinated by two N donors from the 2,2'-bipyridine ligand and three O atoms from three adjacent VO(4) units to form a distorted tetragonal pyramid. These layers are further connected by π-π inter-actions between inter-leaving bipyridine ligands of adjacent layers [centroid-centroid distances = 3.
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