Showing papers in "Journal of the American Chemical Society in 2009"
TL;DR: Two organolead halide perovskite nanocrystals were found to efficiently sensitize TiO(2) for visible-light conversion in photoelectrochemical cells, which exhibit strong band-gap absorptions as semiconductors.
Abstract: Two organolead halide perovskite nanocrystals, CH3NH3PbBr3 and CH3NH3PbI3, were found to efficiently sensitize TiO2 for visible-light conversion in photoelectrochemical cells. When self-assembled on mesoporous TiO2 films, the nanocrystalline perovskites exhibit strong band-gap absorptions as semiconductors. The CH3NH3PbI3-based photocell with spectral sensitivity of up to 800 nm yielded a solar energy conversion efficiency of 3.8%. The CH3NH3PbBr3-based cell showed a high photovoltage of 0.96 V with an external quantum conversion efficiency of 65%.
16,634 citations
TL;DR: A facile, hydrothermal method was developed for the first time to grow oriented, single-crystalline rutile TiO(2) nanorod films on transparent conductive fluorine-doped tin oxide (FTO) substrates.
Abstract: Dye-sensitized solar cells (DSSCs) made from oriented, one-dimensional semiconductor nanostructures such as nanorods, nanowires, and nanotubes are receiving attention because direct connection of the point of photogeneration with the collection electrode using such structures may improve the cell performance. Specifically, oriented single-crystalline TiO2 nanorods or nanowires on a transparent conductive substrate would be most desirable, but achieving these structures has been limited by the availability of synthetic techniques. In this study, a facile, hydrothermal method was developed for the first time to grow oriented, single-crystalline rutile TiO2 nanorod films on transparent conductive fluorine-doped tin oxide (FTO) substrates. The diameter, length, and density of the nanorods could be varied by changing the growth parameters, such as growth time, growth temperature, initial reactant concentration, acidity, and additives. The epitaxial relation between the FTO substrate and rutile TiO2 with a smal...
2,254 citations
TL;DR: A simple, one-pot, "green" synthetic route, based on the "biomineralization" capability of a common commercially available protein, bovine serum albumin (BSA), has been developed for the preparation of highly stable Au nanocrystals (NCs) with red emission and high quantum yield.
Abstract: A simple, one-pot, "green" synthetic route, based on the "biomineralization" capability of a common commercially available protein, bovine serum albumin (BSA), has been developed for the preparation of highly stable Au nanocrystals (NCs) with red emission and high quantum yield.
2,215 citations
TL;DR: Findings place COFs among the most porous and the best adsorbents for hydrogen, methane, and carbon dioxide.
Abstract: Dihydrogen, methane, and carbon dioxide isotherm measurements were performed at 1−85 bar and 77−298 K on the evacuated forms of seven porous covalent organic frameworks (COFs). The uptake behavior and capacity of the COFs is best described by classifying them into three groups based on their structural dimensions and corresponding pore sizes. Group 1 consists of 2D structures with 1D small pores (9 A for each of COF-1 and COF-6), group 2 includes 2D structures with large 1D pores (27, 16, and 32 A for COF-5, COF-8, and COF-10, respectively), and group 3 is comprised of 3D structures with 3D medium-sized pores (12 A for each of COF-102 and COF-103). Group 3 COFs outperform group 1 and 2 COFs, and rival the best metal−organic frameworks and other porous materials in their uptake capacities. This is exemplified by the excess gas uptake of COF-102 at 35 bar (72 mg g−1 at 77 K for hydrogen, 187 mg g−1 at 298 K for methane, and 1180 mg g−1 at 298 K for carbon dioxide), which is similar to the performance of COF...
2,102 citations
TL;DR: A method to disperse and exfoliate graphite to give graphene suspended in water-surfactant solutions and suggests the flakes to be largely free of defects and oxides, although X-ray photoelectron spectroscopy shows evidence of a small oxide population.
Abstract: We have demonstrated a method to disperse and exfoliate graphite to give graphene suspended in water−surfactant solutions. Optical characterization of these suspensions allowed the partial optimization of the dispersion process. Transmission electron microscopy showed the dispersed phase to consist of small graphitic flakes. More than 40% of these flakes had <5 layers with ∼3% of flakes consisting of monolayers. Atomic resolution transmission electron microscopy shows the monolayers to be generally free of defects. The dispersed graphitic flakes are stabilized against reaggregation by Coulomb repulsion due to the adsorbed surfactant. We use DLVO and Hamaker theory to describe this stabilization. However, the larger flakes tend to sediment out over ∼6 weeks, leaving only small flakes dispersed. It is possible to form thin films by vacuum filtration of these dispersions. Raman and IR spectroscopic analysis of these films suggests the flakes to be largely free of defects and oxides, although X-ray photoelect...
2,086 citations
TL;DR: The N-doped reduced GO shows clearly n-type electron doping behavior with the Dirac point (DP) at negative gate voltages in three terminal devices, and electrical measurements of individual GO sheet devices demonstrate that GO anneal in NH(3) exhibits higher conductivity than those annealed in H(2), suggesting more effective reduction of GO by annealing in NH-3 than in H-2, consistent with XPS data.
Abstract: We developed a simple chemical method to obtain bulk quantities of N-doped, reduced graphene oxide (GO) sheets through thermal annealing of GO in ammonia. X-ray photoelectron spectroscopy (XPS) study of GO sheets annealed at various reaction temperatures reveals that N-doping occurs at a temperature as low as 300 °C, while the highest doping level of ∼5% N is achieved at 500 °C. N-doping is accompanied by the reduction of GO with decreases in oxygen levels from ∼28% in as-made GO down to ∼2% in 1100 °C NH3 reacted GO. XPS analysis of the N binding configurations of doped GO finds pyridinic N in the doped samples, with increased quaternary N (N that replaced the carbon atoms in the graphene plane) in GO annealed at higher temperatures (≥900 °C). Oxygen groups in GO were found responsible for reactions with NH3 and C−N bond formation. Prereduced GO with fewer oxygen groups by thermal annealing in H2 exhibits greatly reduced reactivity with NH3 and a lower N-doping level. Electrical measurements of individua...
1,658 citations
TL;DR: Single-layer graphite oxide can be viewed as an unconventional type of soft material and has recently been recognized as a promising material for composite and electronics applications and it is of both scientific curiosity and technical importance to know how these atomically thin sheets assemble.
Abstract: Single-layer graphite oxide can be viewed as an unconventional type of soft material and has recently been recognized as a promising material for composite and electronics applications. It is of both scientific curiosity and technical importance to know how these atomically thin sheets assemble. There are two fundamental geometries of interacting single layers: edge-to-edge and face-to-face. Such interactions were studied at the air−water interface by Langmuir−Blodgett assembly. Stable monolayers of graphite oxide single layers were obtained without the need for any surfactant or stabilizing agent, due to the strong electrostatic repulsion between the 2D confined layers. Such repulsion also prevented the single layers from overlapping during compression, leading to excellent reversibility of the monolayers. In contrast to molecular and hard colloidal particle monolayers, the single layers tend to fold and wrinkle at edges to resist collapsing into multilayers. The monolayers can be transferred to a substr...
1,628 citations
TL;DR: Anatase TiO(2) nanosheets with highly reactive facets exposed have been successfully synthesized by a facile hydrothermal route, taking advantage of a specific stabilization effect of fluorine ion on (001) facets.
Abstract: Anatase TiO2 nanosheets with highly reactive (001) facets exposed have been successfully synthesized by a facile hydrothermal route, taking advantage of a specific stabilization effect of fluorine ion on (001) facets. The percentage of highly reactive (001) facets in such TiO2 nanosheets is very high (up to 89%). In addition, the as-prepared TiO2 nanosheets exhibit excellent activity in the photocatalytic degradation of organic contaminants.
1,504 citations
TL;DR: It is shown that the efficiency of hydrogen production by photochemical water reduction can be improved by approximately 1 order of magnitude by introducing the right type of mesoporosity into polymeric C(3)N(4).
Abstract: We investigated semiconductor characteristics for polymeric carbon nitride as a metal-free photocatalyst working with visible light and have shown that the efficiency of hydrogen production by photochemical water reduction can be improved by ∼1 order of magnitude by introducing the right type of mesoporosity into polymeric C3N4. We anticipate a wide rang of potential application of C3N4 as energy transducers for artificial photosynthesis in general, especially with a 3D continuous nanoarchitecture. Moreover, the results of finding photoactivity for carbon nitride nanoparticles can enrich the discussion on prebiotic chemistry of the Earth, as HCN polymer clusters are unequivocal in the solar system.
1,471 citations
TL;DR: It is reported that N,N-dimethylacetamide containing lithium chloride (LiCl) is a privileged solvent that enables the synthesis of the renewable platform chemical 5-hydroxymethylfurfural (HMF) in a single step and unprecedented yield from untreated lignocellulosic biomass, as well as from purified cellulose, glucose, and fructose.
Abstract: Lignocellulosic biomass is a plentiful and renewable resource for fuels and chemicals. Despite this potential, nearly all renewable fuels and chemicals are now produced from edible resources, such as starch, sugars, and oils; the challenges imposed by notoriously recalcitrant and heterogeneous lignocellulosic feedstocks have made their production from nonfood biomass inefficient and uneconomical. Here, we report that N,N-dimethylacetamide (DMA) containing lithium chloride (LiCl) is a privileged solvent that enables the synthesis of the renewable platform chemical 5-hydroxymethylfurfural (HMF) in a single step and unprecedented yield from untreated lignocellulosic biomass, as well as from purified cellulose, glucose, and fructose. The conversion of cellulose into HMF is unabated by the presence of other biomass components, such as lignin and protein. Mechanistic analyses reveal that loosely ion-paired halide ions in DMA−LiCl are critical for the remarkable rapidity (1−5 h) and yield (up to 92%) of this low...
1,398 citations
TL;DR: It was found that films with finely distributed polymer/fulleride interpenetrating network exhibited improved solar cell conversion efficiency, and the results proved that polymer solar cells have a bright future.
Abstract: This paper describes synthesis and photovoltaic studies of a series of new semiconducting polymers with alternating thieno[3,4-b]thiophene and benzodithiophene units. The physical properties of these polymers were finely tuned to optimize their photovoltaic effect. The substitution of alkoxy side chains to the less electron-donating alkyl chains or introduction of electron-withdrawing fluorine into the polymer backbone reduced the HOMO energy levels of polymers. The structural modifications optimized polymers’ spectral coverage of absorption and their hole mobility, as well as miscibility with fulleride, and enhanced polymer solar cell performances. The open circuit voltage, Voc, for polymer solar cells was increased by adjusting polymer energy levels. It was found that films with finely distributed polymer/fulleride interpenetrating network exhibited improved solar cell conversion efficiency. Efficiency over 6% has been achieved in simple solar cells based on fluorinated PTB4/PC61BM films prepared from m...
TL;DR: The results suggest that the carbon dots remain strongly fluorescent in vivo, which, coupled with their biocompatibility and nontoxic characteristics, might offer great potential for imaging and related biomedical applications.
Abstract: It was found and recently reported that small carbon nanoparticles can be surface-passivated by organic or biomolecules to become strongly fluorescent. These fluorescent carbon nanoparticles, dubbed “carbon dots”, can be successfully used for in vitro cell imaging with both one- and two-photon excitations, as already demonstrated in the literature. Here we report the first study using carbon dots for optical imaging in live mice. The results suggest that the carbon dots remain strongly fluorescent in vivo, which, coupled with their biocompatibility and nontoxic characteristics, might offer great potential for imaging and related biomedical applications.
TL;DR: Potential utility of the new NMOF-based nanodelivery vehicles for optical imaging and anticancer therapy was demonstrated in vitro using HT-29 human colon adenocarcinoma cells.
Abstract: Fe(III)-carboxylate nanoscale metal−organic frameworks (NMOFs) with the MIL-101 structure were synthesized using a solvothermal technique with microwave heating. The ∼200 nm particles were characterized using a variety of methods, including SEM, PXRD, nitrogen adsorption measurements, TGA, and EDX. By replacing a percentage of the bridging ligand (terephthalic acid) with 2-amino terephthalic acid, amine groups were incorporated into the framework to provide sites for covalent attachment of biologically relevant cargoes while still maintaining the MIL-101 structure. In proof-of-concept experiments, an optical contrast agent (a BODIPY dye) and an ethoxysuccinato-cisplatin anticancer prodrug were successfully incorporated into the Fe(III)-carboxylate NMOFs via postsynthetic modifications of the as-synthesized particles. These cargoes are released upon the degradation of the NMOF frameworks, and the rate of cargo release was controlled by coating the NMOF particles with a silica shell. Potential utility of th...
TL;DR: Five new crystalline zeolitic imidazolate frameworks (ZIFs), ZIF-78 to -82, were prepared from zinc(II) nitrate and mixtures of 2-nitroimidazole and five different functionalized imidzoles and were found to have the GME topology.
Abstract: Five new crystalline zeolitic imidazolate frameworks (ZIFs), ZIF-78 to -82, were prepared from zinc(II) nitrate and mixtures of 2-nitroimidazole and five different functionalized imidazoles and were found to have the GME topology. These structures, along with three previously reported GME ZIFs, constitute a series of highly porous materials with Brunauer−Emmet−Teller surface areas ranging from 620 to 1730 m2/g. The pore diameters and apertures vary incrementally from 7.1 to 15.9 A and 3.8 to 13.1 A, respectively, and the functionalities decorating the pores vary from polar cyano- and nitro- groups to nonpolar alkyl groups. The variability expressed in these materials makes them highly attractive for study as gas-separation media. Selectivity values calculated for separation of CO2 and CH4 predict that the ZIFs with polar functionality, ZIF-78 (10.6:1) and -82 (9.6:1), retain CO2 gas to a greater degree than the other members of the GME series and BPL-activated carbon. These predictions are borne out in dy...
TL;DR: The addition of 2-propanol can strengthen the stabilization effect associated with fluorine adsorption over (001) surface and thus stimulate its preferred growth, and the as-prepared anatase TiO(2) single-crystal nanosheets having 64% {001} facets show superior photoreactivity compared to P25 as a benchmarking material.
Abstract: [Yang, Hua Gui; Liu, Gang; Qiao, Shi Zhang; Sun, Cheng Hua; Jin, Yong Gang; Smith, Sean Campbell; Lu, Gao Qing (Max)] Univ Queensland, ARC Ctr Exlcellence Funct Nanomat, Ctr Computat Mol Sci, Brisbane, Qld 4072, Australia. [Sun, Cheng Hua; Smith, Sean Campbell] Univ Queensland, Ctr Computat Mol Sci, Brisbane, Qld 4072, Australia. [Zou, Jin] Univ Queensland, Ctr Microscopy & Microanal, Sch Engn, Brisbane, Qld 4072, Australia. Australian Inst Bioengn & Nanotechnol, Brisbane, Qld 4072, Australia. [Yang, Hua Gui] E China Univ Sci & Technol, Sch Mat Sci & Engn, Minist Educ, Key Lab Ultrafine Mat, Shanghai 200237, Peoples R China. [Liu, Gang; Cheng, Hui Ming] Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Peoples R China.;Qiao, SZ (reprint author), Univ Queensland, ARC Ctr Exlcellence Funct Nanomat, Ctr Computat Mol Sci, Brisbane, Qld 4072, Australia;s.qiao@uq.edu.au maxlu@uq.edu.au
TL;DR: This work improves the understanding of the kinetics of nucleic acid reactions and will be useful in the rational design of dynamic DNA and RNA circuits and nanodevices.
Abstract: DNA is increasingly being used as the engineering material of choice for the construction of nanoscale circuits, structures, and motors. Many of these enzyme-free constructions function by DNA strand displacement reactions. The kinetics of strand displacement can be modulated by toeholds, short single-stranded segments of DNA that colocalize reactant DNA molecules. Recently, the toehold exchange process was introduced as a method for designing fast and reversible strand displacement reactions. Here, we characterize the kinetics of DNA toehold exchange and model it as a three-step process. This model is simple and quantitatively predicts the kinetics of 85 different strand displacement reactions from the DNA sequences. Furthermore, we use toehold exchange to construct a simple catalytic reaction. This work improves the understanding of the kinetics of nucleic acid reactions and will be useful in the rational design of dynamic DNA and RNA circuits and nanodevices.
TL;DR: A new crystalline porous three-dimensional covalent organic framework, termed COF-300, has been synthesized and structurally characterized and shows thermal stability up to 490 degrees C and permanent porosity with a surface area of 1360 m(2) g(-1).
Abstract: A new crystalline porous three-dimensional covalent organic framework, termed COF-300, has been synthesized and structurally characterized. Tetrahedral tetra-(4-anilyl)-methane and linear terephthaldehyde building blocks were condensed to form imine linkages in a material whose X-ray crystal structure shows five independent diamond frameworks. Despite the interpenetration, the structure has pores of 7.2 A diameter. Thus, COF-300 shows thermal stability up to 490 degrees C and permanent porosity with a surface area of 1360 m(2) g(-1).
TL;DR: In contrast to the conventional Pd/C catalyst, graphite oxide and graphene-based catalysts gave much higher activities with turnover frequencies exceeding 39,000 h(-1), accompanied by very low palladium leaching (<1 ppm).
Abstract: Pd2+-exchanged graphite oxide and chemically derived graphenes therefrom were employed as supports for Pd nanoparticles. The influence of catalyst preparation, carbon functionalization, and catalyst morphology on the catalytic activity in the Suzuki−Miyaura coupling reactions was investigated. The catalysts were characterized by means of spectroscopy (FT-IR, solid-state 13C NMR, AAS, XPS), X-ray scattering (WAXS), surface area analysis (BET, methylene blue adsorption), and electron microscopy (TEM, ESEM). In contrast to the conventional Pd/C catalyst, graphite oxide and graphene-based catalysts gave much higher activities with turnover frequencies exceeding 39 000 h−1, accompanied by very low palladium leaching (<1 ppm).
TL;DR: Experiments combined with the density functional theory (DFT) calculation have been performed to understand the underlying photocatalysis mechanism of the nitrogen-doped titania nanobelts, finding that nitrogen doping allows visible-light-responsive photocatalytic activity but lowers UV- light-responsive photochemical activity.
Abstract: Experiments combined with the density functional theory (DFT) calculation have been performed to understand the underlying photocatalysis mechanism of the nitrogen-doped titania nanobelts. Nitrogen-doped anatase titania nanobelts are prepared via hydrothermal processing and subsequent heat treatment in NH3. Both the nitrogen content and the oxygen vacancy concentration increase with increasing the NH3 treatment temperature. Nitrogen doping leads to an add-on shoulder on the edge of the valence band, the localized N 2p levels above the valence band maximum, and the 3d states of Ti3+ below the conduction band, which is confirmed by DFT calculation and X-ray photoelectron spectroscopy (XPS) measurement. Extension of the light absorption from the ultraviolet (UV) region to the visible-light region arises from the N 2p levels near the valence band and from the color centers induced by the oxygen vacancies and the Ti3+ species. Nitrogen doping allows visible-light-responsive photocatalytic activity but lowers U...
TL;DR: A zeolitic imidazolate framework (ZIF-8) as member of the metal-organic framework family has been crystallized as a thin porous layer on an asymmetric ceramic support that can be selected from other gases by molecular sieving.
Abstract: A zeolitic imidazolate framework (ZIF-8) as member of the metal−organic framework family has been crystallized as a thin porous layer on an asymmetric ceramic support. Hydrogen can be selected from other gases by molecular sieving.
TL;DR: MIL-125, the first example of a highly porous and crystalline titanium(IV) dicarboxylate with a high thermal stability and photochemical properties, is presented, a very promising candidate for applications in smart photonic devices, sensors, and catalysis.
Abstract: Titanium is a very attractive candidate for MOFs due to its low toxicity, redox activity, and photocatalytic properties. We present here MIL-125, the first example of a highly porous and crystalline titanium(IV) dicarboxylate (MIL stands for Materials of Institut Lavoisier) with a high thermal stability and photochemical properties. Its structure is built up from a pseudo cubic arrangement of octameric wheels, built up from edge- or corner-sharing titanium octahedra, and terephthalate dianions leading to a three-dimensional periodic array of two types of hybrid cages with accessible pore diameters of 6.13 and 12.55 A. X-ray thermodiffractometry and thermal analysis show that MIL-125 is stable up to 360 °C under air atmosphere while nitrogen sorption analysis indicates a surface area (BET) of 1550 m2·g−1. Moreover, under nitrogen and alcohol adsorption, MIL-125 exhibits a photochromic behavior associated with the formation of stable mixed valence titanium-oxo compounds. The titanium oxo cluster are back ox...
TL;DR: This chemisorption interaction is the strongest reported to date for a metal-organic framework and points toward the potential utility of alkylamine-appended frameworks for the postcombustion capture of CO(2) from low-pressure flue gas streams.
Abstract: Reaction of CuCl2·2H2O with 1,3,5-tris(1H-1,2,3-triazol-5-yl)benzene (H3BTTri) in DMF at 100 °C generates the metal−organic framework H3[(Cu4Cl)3(BTTri)8(DMF)12]·7DMF·76H2O (1-DMF). The sodalite-type structure of the framework consists of BTTri3−-linked [Cu4Cl]7+ square clusters in which each CuII center has a terminal DMF ligand directed toward the interior of a large pore. The framework exhibits a high thermal stability of up to 270 °C, as well as exceptional chemical stability in air, boiling water, and acidic media. Following exchange of the guest solvent and bound DMF molecules for methanol to give 1-MeOH, complete desolvation of the framework at 180 °C generated H3[(Cu4Cl)3(BTTri)8] (1) with exposed CuII sites on its surface. Following a previously reported protocol, ethylenediamine molecules were grafted onto these sites to afford 1-en, featuring terminal alkylamine groups. The N2 adsorption isotherms indicate a reduction in the BET surface area from 1770 to 345 m2/g following grafting. The H2 adso...
TL;DR: A direct relationship between the concentration of the larger size oxygen vacancy clusters and the reducibility/reactivity of nanosized ceria was revealed, which may be an important step in understanding and designing active sites at the surface of metal oxide catalytic materials.
Abstract: CeO2 is a catalytic material of exceptional technological importance, and the precise role of oxygen vacancies is crucial to the greater understanding of these oxide materials. In this work, two ceria nanorod samples with different types and distributions of oxygen vacancies were synthesized. A direct relationship between the concentration of the larger size oxygen vacancy clusters and the reducibility/reactivity of nanosized ceria was revealed. These results may be an important step in understanding and designing active sites at the surface of metal oxide catalytic materials.
TL;DR: The photocatalytic rate was found to have no dependence on ZnO particle size, but the shape factor seems to be of overriding importance, and Hexagonal platelike nanocrystals were found to display at least 5 times higher activity than rod-shaped crystals, which clearly suggests that the polar (001) and (002) faces are more active surfaces than the nonpolar surfaces perpendicular to them.
Abstract: A wet-chemical method was employed to prepare zinc oxide nanocrystals having controlled morphology through thermal decomposition of a zinc precursor in self-assembled supramolecular structures in solvent under mild conditions. This solution method offers finer tailoring of the size and shape of the nanocrystals and is complementary to most reported physical methods. Understanding the morphological effects of pure or modified zinc oxide nanocrystals on photocatalytic activity is important in regard to enhanced solar energy capture and utilization but has been scarcely addressed in the past. The photocatalytic rate was found to have no dependence on ZnO particle size, but the shape factor seems to be of overriding importance. Hexagonal platelike nanocrystals were found to display at least 5 times higher activity than rod-shaped crystals, which clearly suggests that the polar (001) and (001) faces are more active surfaces than the nonpolar surfaces perpendicular to them.
TL;DR: A novel coumarin-based fluorogenic probe bearing the 2-picolyl unit was developed as a fluorescent chemosensor with high selectivity and suitable affinity in biological systems toward Cu(2+) over other cations tested, and results indicate that 1 should be useful for the fluorescence microscopic imaging and the study on the biological functions of Cu( 2+.
Abstract: A novel coumarin-based fluorogenic probe bearing the 2-picolyl unit (1) was developed as a fluorescent chemosensor with high selectivity and suitable affinity in biological systems toward Cu2+ over other cations tested. The fluorescence on−off mechanism was studied by femtosecond time-resolved fluorescence (TRF) upconversion technique and ab initio calculations. The receptor can be applied to the monitoring of Cu2+ ion in aqueous solution with a pH span 4−10. To confirm the suitability of 1 for biological applications, we also employed it for the fluorescence detection of the changes of intracellular Cu2+ in cultured cells. The results indicate that 1 should be useful for the fluorescence microscopic imaging and the study on the biological functions of Cu2+.
TL;DR: A bioinspired iron-based catalyst with semiconductor photocatalytic functions in combination with a high surface area holds promise for synthetic chemistry via combining photocatalysis with organosynthesis through using g-C(3)N(4) nanoparticles.
Abstract: A bioinspired iron-based catalyst with semiconductor photocatalytic functions in combination with a high surface area holds promise for synthetic chemistry via combining photocatalysis with organosynthesis. Here exemplified for phenol synthesis, Fe-g-C3N4/SBA-15 is able to oxidize benzene to phenol with H2O2 even without the aid of strong acids or alkaline promoters. By taking advantage of both catalysis and photocatalyisis functions of g-C3N4 nanoparticles, the yield of the phenol can be markedly promoted.
TL;DR: A porous anionic metal-organic framework, bio-MOF-1, constructed using adenine as a biomolecular building block is described and its potential as a material for controlled drug release is investigated.
Abstract: A porous anionic metal-organic framework, bio-MOF-1, constructed using adenine as a biomolecular building block is described. The porosity of this material is evaluated, its stability in biological buffers is studied, and its potential as a material for controlled drug release is investigated. Specifically, procainamide HCl is loaded into the pores of bio-MOF-1 using a simple cation exchange process. Exogenous cations from biological buffers are shown to affect the release of the adsorbed drug molecules.
TL;DR: Functionalizing the well-known MIL-53(Al) metal-organic framework with amino groups increases its selectivity in CO(2)/CH(4) separations by orders of magnitude while maintaining a very high capacity forCO(2) capture.
Abstract: Functionalizing the well-known MIL-53(Al) metal−organic framework with amino groups increases its selectivity in CO2/CH4 separations by orders of magnitude while maintaining a very high capacity for CO2 capture.
TL;DR: A new low band gap semiconducting polymer, PTB1, was synthesized and found promising for solar energy harvesting, and an external quantum efficiency of 67% and fill-factor of 65% are achieved, both of which are among the highest values reported for a solar cell system based on a lowBand gap polymer.
Abstract: A new low band gap semiconducting polymer, PTB1, was synthesized and found promising for solar energy harvesting. Simple polymer solar cells based on PTB1 and methanofullerene [6,6]-phenyl-C71-butyric acid methyl esters (PC71BM) exhibit a solar conversion efficiency of 5.6%. An external quantum efficiency of 67% and fill-factor of 65% are achieved, both of which are among the highest values reported for a solar cell system based on a low band gap polymer.
TL;DR: It is found consistently that under ambient conditions the copper deficient Cu(1.97)S (djurleite) is more stable than Cu(2) S (chalcocite) and this may be the reason behind the traditionally known instability of the bulk Cu( 2)S/CdS interface.
Abstract: Cu2−xS (x = 1, 0.2, 0.03) nanocrystals were synthesized with three different chemical methods: sonoelectrochemical, hydrothermal, and solventless thermolysis methods in order to compare their common optical and structural properties. The compositions of the Cu2−xS nanocrystals were varied from CuS (covellite) to Cu1.97S (djurleite) through adjusting the reduction potential in the sonoelectrochemical method, adjusting the pH value in the hydrothermal method and by choosing different precursor pretreatments in the solventless thermolysis approach, respectively. The crystallinity and morphology of the products were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), which shows that most of them might be of pure stoichiometries but some of them are mixtures. The obtained XRDs were studied in comparison to the XRD patterns of previously reported Cu2−xS. We found consistently that under ambient conditions the copper deficient Cu1.97S (djurleite) is more stable than Cu2S (chalco...