A facile hydrothermal method for preparation of fluorescent carbon dots on application of Fe3+ and fingerprint detection.

The carbon dots (CDs) was prepared by a facile hydrothermal treatment of citric acid and glycine at 180 °C. The CDs at around 3.2 nm was collected after filtration and dialysis. The sample displayed green fluorescence (G-CDs) with a quantum yield of 3.7% in high concentration and the strongest emission peak was at 545 nm under the excitation wavelength of 480 nm; the blue fluorescence CDs (B-CDs) with a quantum yield of 29.8% was obtained after diluted either in solution or in powder, the strongest emission peak was located at 475 nm under the excitation wavelength of 380 nm. The G-CDs possessed a high selectivity to Fe3+, which was in a linear range of 0-3.5 µM with the detection limit of 0.21 µM. The CDs powder with blue fluorescence at a relative low content was obtained and adaptable for the fingerprint detection on substrates of litmus paper, resin tabletop, glass, and orange plastic ruler.

Nitrogen-containing activated carbon of improved electrochemical performance derived from cotton stalks using indirect chemical activation.

Highly porous (specific surface area, SBET, 1400 m2/g) and rich in surface groups activated carbons (ACs) were obtained from cotton stalks using either a direct or indirect activation. They were characterized by adsorption of nitrogen, thermal analysis combined with mass spectrometry, potentiometric titration, and X-ray photoelectron spectroscopy (XPS). XPS analysis indicated that the indirect activation led to more nitrogen on the surface incorporated as pyridinic and graphitic/quaternary species. These species were beneficial for a carbon application as oxygen reduction reaction (ORR) electrocatalysts and supercapacitors. The carbons were catalytically active in ORR with a number of electron transfer from 2.15 to 3.40 and onset potential of 0.810 V vs. reference hydrogen electrode (RHE). Their capacitance was around 180 F g-1 at 1 A g-1 when measured in an alkaline medium. The dependence of the performance on the porosity and nitrogen content was found, indicating suitability of cotton stalks obtained using the indirect activation as precursors of carbons of promising electrochemically active features.

Mesoporous Phosphorus-Doped g-C3N4 Nanostructured Flowers with Superior Photocatalytic Hydrogen Evolution Performance.

Graphitic carbon nitride (g-C3N4) has been deemed a promising heterogeneous metal-free catalyst for a wide range of applications, such as solar energy utilization toward water splitting, and its photocatalytic performance is reasonably adjustable through tailoring its texture and its electronic and optical properties. Here phosphorus-doped graphitic carbon nitride nanostructured flowers of in-plane mesopores are synthesized by a co-condensation method in the absence of any templates. The interesting structures, together with the phosphorus doping, can promote light trapping, mass transfer, and charge separation, enabling it to perform as a more impressive catalyst than its pristine carbon nitride counterpart for catalytic hydrogen evolution under visible light irradiation. The catalyst has low cost, is environmentally friendly, and represents a potential candidate in photoelectrochemistry.

Mesoporous cerium phosphonate nanostructured hybrid spheres as label-free Hg²âº fluorescent probes.

Porous phosphonate-based organic-inorganic hybrid materials have been shown to have novel and amazing physicochemical properties due to the integration of superiorities from both inorganic components and organic moieties. Herein, mesoporous cerium phosphonate nanostructured hybrid spheres are prepared with the assistance of cationic surfactant cetyltrimethylammonium bromide while using ethylene diamine tetra(methylene phosphonic acid) as the coupling molecule. The resulting hybrid is constructed from the cerium phosphonate nanoparticles, accompanied by high specific surface area of 455 m(2) g(-1). The uniform incorporation of rare-earth element cerium and organophosphonic functionalities endows mesoporous cerium phosphonate with excellent fluorescence properties for the development of an optical sensor for selective Hg(2+) detection on the basis of the fluorescence-quenching mechanism. The signal response of mesoporous cerium phosphonate against the Hg(2+) concentration is linear over the range from 0.05 to 1.5 µmol L(-1), giving a limit of detection of 16 nmol L(-1) (at a signal-to-noise ratio of 3). Most of the common physiologically relevant cations and anions did not interfere with the detection of Hg(2+). This label-free system provides a promising platform for further use in bioimaging and biomedical fields.

Hollow cobalt phosphonate spherical hybrid as high-efficiency Fenton catalyst.

Organic-inorganic hybrid of cobalt phosphonate hollow nanostructured spheres were prepared in a water-ethanol system through a mild hydrothermal process in the absence of any templates using diethylenetriamine penta(methylene phosphonic acid) as bridging molecule. SEM, TEM and N2 sorption characterization confirmed a hollow spherical micromorphology with well-defined porosity. The structure and chemical states of the hybrid materials were investigated by FT-IR, XPS and thermogravimetric analysis, revealing the homogeneous integrity of inorganic and organic units inside the network. As a heterogeneous catalyst, hollow cobalt phosphonate material exhibited considerable catalytic oxidizing decomposition of methylene blue with sulfate radicals as compared to cobalt phosphonate nanoparticles synthesized in single water system, which could be attributed to enhanced mass transfer and high surface area for the hollow material. Some operational parameters, including pH and reaction temperature, were found to influence the oxidation process. The present results suggest that cobalt phosphonate material can perform as an efficient heterogeneous catalyst for the degradation of organic contaminants, providing insights into the rational design and development of alternative catalysts for wastewater treatment.

Hollow manganese phosphonate microspheres with hierarchical porosity for efficient adsorption and separation.

Hollow manganese phosphonate microspheres of an inorganic-organic hybrid with hierarchically porous shells were prepared through a template-free hydrothermal method using ethylene diamine tetra(methylene phosphonic acid) as the coupling molecule. The hollow structures with hierarchical porosity were confirmed by SEM, TEM and N2 sorption. FT-IR, XPS and TG-DSC measurements revealed that the organophosphonate linkers were homogeneously incorporated into the hybrid framework. The hierarchical manganese phosphonates could be used as efficient adsorbents for the removal of copper ions, showing fast binding kinetics due to the well-structured porosity. The adsorption process follows pseudo-second order reaction kinetics, as well as Langmuir isotherm, indicating that Cu(2+) was monolayer adsorbed on the hybrid by chemical complexation. Furthermore, the synthesized manganese phosphonates with peculiar porosity exhibited excellent size selectivity for protein adsorption in a complex solution, presenting the promising potential as candidates for biomaterials.

Zn/Mn-MOFs with `S-shaped' packing modes.

Two novel polymers exhibiting metal-organic frameworks (MOFs) have been synthesized by the combination of a metal ion with a benzene-1,3,5-tricarboxylate ligand (BTC) and 1,10-phenanthroline (phen) under hydrothermal conditions. The first compound, poly[[(µ4-benzene-1,3,5-tricarboxylato-κ(4)O:O':O'':O''')(µ-hydroxido-κ(2)O:O)bis(1,10-phenanthroline-κ(2)N,N')dizinc(II)] 0.32-hydrate], {[Zn2(C9H3O6)(OH)(C12H8N2)2]·0.32H2O}n, denoted Zn-MOF, forms a two-dimensional network in which a binuclear Zn2 cluster serves as a 3-connecting node; the BTC trianion also acts as a 3-connecting centre. The overall topology is that of a 6(3) net. The phen ligands serve as appendages to the network and interdigitate with phen ligands belonging to adjacent parallel sheets. The second compound, poly[[(µ6-benzene-1,3,5-tricarboxylato-κ(7)O(1),O(1'):O(1):O(3):O(3'):O(5):O(5'))(µ3-hydroxido-κ(2)O:O:O)(1,10-phenanthroline-κ(2)N,N')dimanganese(II)] 1.26-hydrate], {[Mn2(C9H3O6)(OH)(C12H8N2)]·1.26H2O}n, denoted Mn-MOF, exists as a three-dimensional network in which an Mn4 cluster serves as a 6-connecting unit, while the BTC trianion again plays the role of a 3-connecting centre. The overall topology is that of the rutile net. Phen ligands act as appendages to the network and form the `S-shaped' packing mode.

Adsorption of Cu(2+) and methyl orange from aqueous solutions by activated carbons of corncob-derived char wastes.

Corncob-derived char wastes (CCW) obtained from biomass conversion to syngas production through corncob steam gasification, which were often discarded, were utilized for preparation of activated carbon by calcination, and KOH and HNO3 activation treatments, on the view of environment protection and waste recycling. Their adsorption performance in the removal of heavy metal ions and dye molecules from wastewater was evaluated by using Cu(2+) and methyl orange (MO) as the model pollutant. The surface and structure characteristics of the CCW-based activated carbons (CACs) were investigated by N2 adsorption, CO2 adsorption, FT-IR, and He-TPD. The adsorption capacity varied with the activation methods of CACs and different initial solution concentrations, indicating that the adsorption behavior was influenced by not only the surface area and porosity but also the oxygen functional groups on the surface of the CACs. The equilibrium adsorption data were analyzed with the Langmuir, Freundlich, and Temkin isotherm models, and the adsorption kinetics was evaluated by the pseudo-first-order and pseudo-second-order models.

Ordered mesoporous carbon catalyst for dehydrogenation of propane to propylene.

Metal-free ordered mesoporous carbons were demonstrated to be robust catalysts for direct dehydrogenation of propane to propylene, in the absence of any auxiliary steam, exhibiting high activity and selectivity, as well as long catalytic stability, in comparison with nanostructured carbons.

Pressure-induced first-order phase transition in (NH4)2V3O8 fresnoite: a double coordination change for V4+ and V5+.

The high-pressure behaviour of (NH(4))(2)V(3)O(8) with the fresnoite structure (P4bm, Z = 2) has been studied at room temperature with single-crystal X-ray diffraction in diamond anvil cells using laboratory and synchrotron facilities. At ambient conditions, the crystal structure is composed of layers of corner-sharing V(5+)O(4) tetrahedra and V(4+)O(5) square pyramids separated by layers of the NH(4)(+) cations. At about 3 GPa, there occurs a reversible first-order phase transition to a three-dimensional structure (P4/mbm, Z = 2) built of corner-sharing V(5+)O(5) trigonal bipyramids and V(4+)O(6) octahedra. The NH(4)(+) cations fill up the interstitial sites in the tunnels formed by the vanadate framework. Up to the phase transition, the a lattice parameter of the low-pressure polymorph does not change while the contraction perpendicular to the stacking of the V(3)O(8) slabs accounts entirely for the bulk compressibility. Above the phase transition, the a lattice parameter slightly expands. The structural features of the high-pressure phase of (NH(4))(2)V(3)O(8) are compared to those of other vanadium oxides.

Hexagonal mesoporous titanium tetrasulfonates with large conjugated hybrid framework for photoelectric conversion.

Ordered hexagonal mesoporous titanium tetrasulfonate materials (CuPcS4-Ti) were synthesized through a hydrothermal process with the assistance of surfactant F127, by using the copper(II) phthalocyanine-tetrasulfonic acid tetrasodium salt (CuPcS4) as coupling molecules. It was confirmed by TEM, IR, UV-vis, TGA-DSC, and XRD analysis that the CuPcS4 groups were homogenously incorporated into the hybrid framework, and the synthesized materials could be stable to around 328 °C with the hybrid framework and ordered mesopores well-preserved. A high dye content of Ti/CuPcS4 molar ratio at around 50 was achieved, which could be useful in the photoelectric conversion applications. A novel model of isolated dye centers surrounded by semiconductor oligomers was set, which could effectively suppress the aggregation of dye molecules that may decrease the conversion efficiency in some traditional dye-sensitized solar cells. It was proved that the synthesized CuPcS4-Ti exhibited a relatively high conversion efficiency of 0.53%. It was very valuable to access such a high conversion efficiency by using low-cost and commercially available dye molecules instead of using the expensive unsymmetrical phthalocyanines synthesized by the time-consuming methods in the literature.

Design of open-framework germanates by combining different building units.

Open-framework germanates with extra-large channels are built from two different types of clusters. The two different clusters are connected in such a way to form a pseudo-body-centered cluster aggregate (PBCCA). The different packing of PBCCAs resulted in different 3D open-framework germanates.

Tailoring the porous hierarchy of titanium phosphates.

First hierarchical titanium phosphate (TiPO) materials with multiple porosities of different lengths (meso-macroporous and meso-macro-macroporous) were synthesized by the self-formation process. The further tuning of the porous hierarchy by using the poly(ethylene oxide) surfactant technique was demonstrated. The macroporous structure (50-160 nm in size) of TiPO with mesoporous walls could be self-formed in the absence of any templatable agents, including surfactant molecules. On the basis of spontaneous structurization, the addition of a small quantity of nonionic poly(ethylene oxide) surfactant (e.g., 5%) led to an improvement in macroporosity in abundance and in regularity with a slight enlargement in macropore sizes to 80-250 nm. Interestingly, a secondary, larger macropore system with parallel channels 500-1000 nm in size was generated when the synthesis was performed with moderately increasing the content of surfactant (10%), giving rise to an unprecedented trimodal meso-macro-macroporous structure. A uniform three-dimensional co-continuous macroporous structure with accessible wormhole-like mesoporous walls was synthesized by using the higher content of surfactants. This is a direct demonstration of tailoring the porous hierarchy of different lengths integrated in one solid body by fine-tuning the self-formation process and the participation of surfactant. The synthesized hierarchical titanium phosphates possess interesting optical and acidic properties, which should be significant for large application potential from catalysis and separation to electrochromic devices, fuel cells, and bioactive materials.

Thermally stable macroporous zirconium phosphates with supermicroporous walls: a self-formation phenomenon of hierarchy.

A self-formation phenomenon leading to the hierarchically thermally stable macroporous zirconium phosphates with amorphous supermicroporous walls from the precursors of zirconium propoxide and orthophosphoric acid solution was observed.