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Dyes are usual contaminants in aqueous solution. Some of them are carcinogenic and toxic. Hydroxyl‐carboxyl bifunctional hyper‐crosslinked polymers (HCHCP) carrying hydroxyl and carboxyl groups on their surface were fabricated for methylene blue (MB) adsorption by Friedel‐Crafts alkylation, using 3,4‐dihydroxyphenylacetic acid as a monomer. The maximum adsorption amount of MB was 751.88 mg g−1 according to the Langmuir isotherm model. The adsorption kinetics results demonstrated that the adsorption of MB followed the pseudo‐second‐order kinetic mode. In addition, the results of selective adsorption displayed that the HCHCP could separate MB from Acid Red 91 and methyl orange. Thus, HCHCP are promising adsorbents for cationic dyes. [ABSTRACT FROM AUTHOR]

Yellow-emitting carbon quantum dots, named Y-CQDs, were synthesized from O-phenylenediamine and ethylene glycol via a one-pot hydrothermal method. A fluorescent IMPLICATION logic gate for the continuous and "on–off–on" detection of Au3+ and biothiols in tap water at the nanoscale level was constructed based on these QDs. It showed promise in real sample detection and also as a fluorescent ink. [ABSTRACT FROM AUTHOR]

Iron is recognized as a physiological requirement for anammox bacteria (AnAOB), with Fe(II) considered to be the most effective form. However, Fe(III), instead of Fe(II) is the common iron form in natural and artificial ecosystems. In this study, the nitrogen removal performance and metabolic mechanisms in anammox consortia with soluble and non-soluble Fe(III) as the sole iron element were investigated. After the 150-day operation, the soluble (FeCl 3) and insoluble (Fe 2 O 3) Fe(III)-fed anammox systems reached nitrogen removal rates of 71.84 ± 0.80% and 50.20 ± 0.98%, respectively. AnAOB could survive with soluble (FeCl 3) or insoluble (Fe 2 O 3) Fe(III) as the sole iron element, reaching relative abundances of 18.49% and 13.16%, respectively. The results show that the formation of anammox core consortia can enable AnAOB's survival to adverse external conditions of Fe(II) deficiency. Metagenomic and metatranscriptomic analysis reveal that Ca. Kuenenia can only uptake Fe(II) into the cell for metabolisms either independently through the extracellular electron transfer or with the cross-feeding of symbiotic microbes. This study provides insight into the utilization and metabolic mechanisms of Fe(III) in Ca. Kuenenia-dominated consortia, and deepens the understanding of anammox core consortia in the nitrogen, carbon, and iron cycling, further promoting the practical applications of anammox processes. [Display omitted] • AnAOB can survive in environments with Fe(III) as the sole iron element. • Soluble Fe(III) is more favorable for the survival of Ca. Kuenenia. • Symbiotic bacteria could release acetate to dissolve non-soluble Fe(III). • Extracellular electron transfer in AnAOB converted Fe 2 O 3 into soluble Fe(II). • Ca. Kuenenia can only uptake Fe(II) converted by symbiotic bacteria from Fe(III). [ABSTRACT FROM AUTHOR]

The polymer additives may migrate out from polymer plastics into foods and drinks and their potential risk should not be ignored. In this study, amino group modified magnetic mesoporous silica microspheres were prepared by an in situ method. The magnetic microspheres as adsorbent of magnetic solid-phase extraction (MSPE) were coupled with high performance liquid chromatography (HPLC) to determine nine kinds of polymer additives including antioxidants and ultraviolet absorbers. An excellent linearity (0.9999 ≥ R2 ≥ 0.9994) was at the range of 1.25–1000 ng/mL under optimized conditions. The limits of detection (LODs) and quantification were 0.01–0.09 ng/mL and 0.02–0.30 ng/mL, respectively, for the nine polymer additives, which was lower than those previously reported. This method can be used for the quantitative determination of the migration levels of seven kinds of polymer additives in real foods and drinks packed with plastics. [ABSTRACT FROM AUTHOR]

A three‐dimensional molecularly imprinted overoxidized polypyrrole/MnO2/carbon felt (MIOPPy/MnO2/CF) composites were fabricated, which results in increased active area of the surface of the molecularly imprinted polymers film and greatly improved electrochemical chiral recognition effect for tryptophan isomers. The composites were characterized by field emission scanning electron microscope, transmission electron microscope, X‐ray diffractometer, UV‐visible spectra, N2 adsorption‐desorption isotherms, and electrochemical methods. The manuscript provides a proof of concept and shows promising potential of the prepared composites for chiral recognition. [ABSTRACT FROM AUTHOR]

A rapid, cost-effective and quencher-free fluorescence-based analytical method for sensitive detection of l -cysteine (Cys) based on 2-aminopurine (2-AP) labeled DNA probe and exonuclease I (Exo I) activity was developed. 2-AP labeled DNA probe includes two thymine (T)-T mismatches, which can bind with Hg2+ to form T-Hg2+-T pairing bases, resulting in stable hairpin with five base pairs in its stem. The target Cys can remove Hg2+ from the stem of the hairpin probe based on the high affinity of Cys with Hg2+, leading to the unfolding of the hairpin probe. At last, by adding Exo I, the resulted single-stranded DNA (ssDNA) will be digested to release free 2-AP with strong fluorescence. Under the optimal conditions, the sensing system exhibited a good and wider linear range from 0.4 to 400 nM (R2 = 0.997) and a detection limit as low as 0.16 nM for Cys. Furthermore, other amino acids without reductive sulfur group did not generate obvious change in fluorescence signals. Finally, the sensor can be used in diluted real samples with a good recovery rate, showing promising application in food, environmental and medical analysis. Image 1 • A simple, cost-effective and fluorescent method for Cys detection using 2-AP modified DNA probe was developed. • This assay owns high selectivity, low detection limit of 0.16 nM and wider linear range of 0.4–400 nM. • This method operates in manner of "mix, incubate and detect" and the analytical process is fast. [ABSTRACT FROM AUTHOR]

In this study, magnetic zeolitic imazolate framework-8 (Fe 3 O 4 @ZIF-8) was successfully synthesized by a typical hydrothermal method. The facile magnetic solid-phase extraction (MSPE) based on Fe 3 O 4 @ZIF-8 was proposed for concentrating polymer additives (antioxidants and ultraviolet absorbers). The conditions of MSPE process were optimized. An analytical method of magnetic solid-phase extraction followed by high performance liquid chromatography (MSPE-HPLC) was successfully established for the simultaneous determination of seven polymer additives in drinks and foods packed with plastic. The established method showed good precision, reproducibility, stability, and accuracy with the low limits of detection (0.03–0.15 ng/mL) and limits of quantification (0.08–0.50 ng/mL). The results of this study indicated the Fe 3 O 4 @ZIF-8 coupled with HPLC provided an efficient enrichment and determination method for polymer additives in drinks and foods. [ABSTRACT FROM AUTHOR]

A high stable and efficient catalyst of CuO@CSs (carbon silicion sphere@CuO) was prepared through in-situ growth methods. CuO@CSs as a heterojunction was conducive to activate PMS efficiently. 15 ppm of RhB was completely removed after 2 min with 0.5 mM peroxymonosulfate (PMS) under UV–visible light irradiation. The reusability of catalyst was evaluated through recycling tests, and the RhB degradation efficiency ranged from 99.96% to 99.37% after five cycles. 1O 2 and O 2 •−were detected by trapping experiments and electron paramagnetic resonance (EPR) in the photocatalytic degradation, which have worked together in the removal of RhB. Furthermore, the CuO@CSs/PMS was applied to treat natural water containing RhB, which was completely decomposed within 8 min. The possible photocatalytic degradation mechanism for the RhB was investigated. The degradation pathway of RhB was deduced through LC-MS results, it was concluded that CuO@CSs was a recyclable catalyst to activate PMS and remove organic pollution. • CSs@CuO revealed perfect degradation efficiency, 15 ppm of RhB was completely degraded within 2 min with 0.5 mM PMS under UV–visible light irradiation. • CSs@CuO exhibited good reusability by recycling tests. • CSs@CuO displayed outstanding photocatalytic performance for removing RhB from raw water. [ABSTRACT FROM AUTHOR]

A sulfonated chiral diamine ligand anion-based functionalized ionic liquid has been synthesized. Then the new ionic liquid-regulating ruthenium complexes were prepared successfully and employed as efficient catalysts for the asymmetric transfer hydrogenation of various ketones. The catalysts were highly efficient for the hydrogenation of a wide range of substrates bearing different functional groups and could be separated easily from the reaction mixture by thermoregulated phase separation, which can be efficiently recycled five times without significant changes in catalytic activity and enantioselectivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel carbon composite was integrated with Au@Pt core–shell nanoparticles to detect glucose. • GO-dispersed MWCNTs effectively prevents the aggregation of the MWCNTs. • The full contact of GO and MWCNTs improves the specific surface area. • Au@Pt NPs produces synergistic electrocatalytic performance for glucose sensing. A novel carbon composite was integrated with Au@Pt core–shell nanoparticles (Au@Pt NPs) to construct a sensing interface for enzyme-free electrochemical detection of glucose. As surfactant, graphene oxide (GO) was used to disperse multi-walled carbon nanotubes (MWCNTs). After the glassy carbon electrode (GCE) was modified with the mixture of GO and MWCNTs, the Au@Pt NPs were decorated on it. The prepared novel three-dimensional sensor interface was applied to detect glucose without enzyme at a remarkable negative potential (at about −0.013 V vs. Ag/AgCl), demonstrating a low detection limit (4.2 × 10−8 M) and two wide linear range from 5 × 10−8 to 1 × 10−4 M and 1 × 10−4 M to 2.5 × 10−3 M. In addition, the non-enzymatic glucose sensing platform can be realized for practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple method for preparing hierarchical porous structure from CNC and urea. • The electrode comprised of NHPC exhibits a wide linear range to recognize AA. • NHPC/GCE demonstrates high selectivity and low oxidation potential. The sensing application of cellulose nanocrystals (CNCs) is fascinating. CNCs can't produce electrical or optical signals directly. Different from published sensing methods, a novel and simple electrochemical sensor for sensitive and selective detection of ascorbic acid (AA) was constructed based on three-dimensional nitrogen-doped hierarchical porous carbons (NHPC) by carbonizing CNCs and urea. Compared with bare glassy carbon electrode (GCE), the presence of porous carbons effectively increases the electron transport between analytes and the electrode, and significantly reduces the overpotential of AA oxidation. Under the optimum conditions, the electrode comprised of NHPC exhibits an extremely wide linear range from 8 × 10−5 to 1 × 10−2 M (R2 = 0.9996) and 1 × 10−6 to 5 × 10−5 M (R2 = 0.9867) to recognize the AA molecules, with a low detection limit of 2.45 × 10−7 M (S/N = 3) at a sensitivity of 0.1138 μA μM−1 cm−2. In particular, the sensing system for AA detection was further verified by the successful monitoring of AA in some spiked real samples. The fabricated nitrogen-doped CNC-based porous carbon material shows broad potential in the electrochemical application. [ABSTRACT FROM AUTHOR]

Synthesis of N-CQDs and its sensing mechanism for Fe3+, AA and H 2 O 2. [Display omitted] • A simple "on-off-on-off" continuous response fluorescence sensor was developed. • The analytical process is fast, and the three inputs "Logic gate" is achieved. In this study, an environmentally friendly and water-soluble nitrogen-doped carbon quantum dots (N-CQDs) with quantum yield (QY) of 8.59% were prepared by one-step hydrothermal synthesis without any chemical reagent using the leaves of prunus lannesiana as precursors. The properties and quality of N-CQDs were investigated by Ultraviolet–visible absorption spectroscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, zeta potential, high-resolution transmission electron microscopy and fluorescence spectroscopy. The fluorescence of the prepared N-CQDs can be quenched by Fe3+ through the synergistic effect of the formation of non-fluorescent complex and internal filtration effect (IFE) between Fe3+ and N-CQDs. And the quenched fluorescence can be "turned on" after adding ascorbic acid (AA) because Fe3+ can be released from the surface of N-CQDs through the redox reaction between AA and Fe3+. While the restored fluorescence can be "turned off" again by hydrogen peroxide (H 2 O 2) due to the re-oxidation of Fe2+ to Fe3+. So, the three inputs "logic gate" is achieved and the "on-off-on-off" continuous response fluorescence sensor is formed, which can be applied for the continuous detection of Fe3+, AA and H 2 O 2 with the linear range of 40–260 μM, 10–200 μM and 40–140 μM, respectively. Finally, the sensor was successfully applied to determine Fe3+, AA and H 2 O 2 in real samples with the satisfactory recoveries (95.35%-104.10%) and repeatability (relative standard deviation (RSD) ≤ 1.68%). The continuous response fluorescence sensor prepared by simple green synthesis route has the characteristics of fast response, acceptable sensitivity and good selectivity. [ABSTRACT FROM AUTHOR]

• An enhanced electrochemical enantioselective platform for tryptophan (Trp) enantiomers was constructed. • β-CD-containing polymers (P-CDPs) own chiral microenvironment, high surface area and permanent porosity. • P-CDPs and multiwalled carbon nanotubes (MWCNTs) produce synergistic effect for electrochemical chiral recognition. • The method could predict the ratio of l - or d -isomers in racemic mixture. Porous β-CD-containing polymers (P-CDPs), the polymerization product of β-CD and tetrafluoroterephthalonitrile, demonstrate the high surface area and permanent porosity, which has been applied in removal of organic micropollutants and sulfides by molecular recognition. In this manuscript, an enhanced electrochemical enantioselective platform for tryptophan (Trp) enantiomers was constructed by layer by layer assembly of multiwalled carbon nanotubes (MWCNTs) and P-CDPs on the surface of GCE. The morphologies and performances of the modified electrodes were fully characterized and determined by high resolution field emission scanning electron microscopy (FESEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). And the operation parameters such as temperature and pH on the performance of electrochemical recognition were optimized. Under the optimal experimental conditions, the peak current ratio (I l -Trp / I d -Trp) could reach 2.60. The linear range for the detection of l -Trp on P-CDP/MWCNT/GCE is 8 × 10-6 M to 2 × 10-3 M and for d -Trp is 8 × 10-6 M to 4 × 10-3 M. In addition, the method could predict the ratio of l - or d -isomers in racemic mixture. [ABSTRACT FROM AUTHOR]

Vesicle, a microscopic unit that encloses a volume with an ultrathin wall, is ubiquitous in biomaterials. However, it remains a huge challenge to create its inorganic metal-based artificial counterparts. Here, inspired by the formation of biological vesicles, we proposed a novel biomimetic strategy of curling the ultrathin nanosheets into nanovesicles, which was driven by the interfacial strain. Trapped by the interfacial strain between the initially formed substrate Rh layer and subsequently formed RhRu overlayer, the nanosheet begins to deform in order to release a certain amount of strain. Density functional theory (DFT) calculations reveal that the Ru atoms make the curling of nanosheets more favorable in thermodynamics applications. Owing to the unique vesicular structure, the RhRu nanovesicles/C displays excellent hydrogen oxidation reaction (HOR) activity and stability, which has been proven by both experiments and DFT calculations. Specifically, the HOR mass activity of RhRu nanovesicles/C are 7.52 A mg(Rh+Ru)−1 at an overpotential of 50 mV at the rotating disk electrode (RDE) level; this is 24.19 times that of commercial Pt/C (0.31 mA mgPt−1). Moreover, the hydroxide exchange membrane fuel cell (HEMFC) with RhRu nanovesicles/C displays a peak power density of 1.62 W cm−2 in the H2-O2 condition, much better than that of commercial Pt/C (1.18 W cm−2). This work creates a new biomimetic strategy to synthesize inorganic nanomaterials, paving a pathway for designing catalytic reactors. [ABSTRACT FROM AUTHOR]

The metal-nitrogen-carbon (M-N-C) type oxygen reduction reaction (ORR) catalysts are promising for hydroxide exchange membrane fuel cells, but catalysts with further improved performance are challenging. Here, we report the efficient improvement of the ORR activity of M-N-C catalysts by employing highly polarizable metal cation Ag+. Ag, Fe single atomic sites embedded in concave nitrogen doped carbon (Ag 1 Fe 1 /CNC) is successfully synthesized and shows high performance towards ORR, indicating by both the ultra-high half-wave potential of 0.917 V and membrane electrolyte assembly performance of peak power density up to 1.26 W cm−2. The binding energy of the ORR intermediates on the highly polarizable Ag site in Ag 1 Fe 1 /CNC was significantly tuned by the adjacent Fe site by more than 0.2 eV, and thus leading to a low theoretical ORR overpotential of only 0.398 V. The employment of the highly polarizable metal cation brings a novel and efficient approach to construct highly active catalysts. [Display omitted] • High performance oxygen reduction reaction catalyst Ag 1 Fe 1 /CNC is synthesized. • The highly polarizable Ag site shows ultra-high catalytic activity. • The Ag sites are significantly affect by the adjacent metals. • High membrane electrolyte assembly performance is achieved by using Ag 1 Fe 1 /CNC. [ABSTRACT FROM AUTHOR]

Fisch is homologous medicine for food plant and health-protective affection in the human body system. To further understand the functions of G. uralensis Fisch, separation of the bioactive compounds from this natural product is very important. A general three-liquid-phase flotation (TLPF) technique was established to separate and concentrate five bioactive compounds from G. uralensis Fisch. The three-liquid-phase system, pH of initial aqueous phase, (NH4)2SO4 concentration, nitrogen flow rate, and flotation time were investigated. The flotation efficiency of liquiritin apioside, liquiritin, and glycyrrhizic acid in the middle phase and semilicoisoflavone B and licoisoflavone B in the upper phase could reach 91.24%, 94.23%, 88.04%, 94.67%, and 96.44%, respectively. Furthermore, the established TLPF was used for separation of four kinds of anthraquinones from Cassiae Semen. The results showed that TLPF is feasible for separating the compounds with quite a different polarity from natural products. TLPF: Three-liquid-phase flotation; TLPS: Three-liquid-phase system; prep-HPLC: Preparative high-performance liquid chromatography; TLPE: Three-liquid-phase extraction; ATPF: Aqueous two-phase flotation. [ABSTRACT FROM AUTHOR]

The use of platinum group metals (PGMs) as the catalysts and the requirement of high purity H 2 are the two aspects resulting in the high cost of the polymer electrolyte membrane fuel cells. Herein, we report that nitrogen-doped carbon encapsulated nickel nanoparticles (Ni@NC) as stable hydrogen oxidation reaction catalysts, which allows the use of PGM-free anode catalysts durably and feeding crude hydrogen. The hydroxide exchange membrane fuel cell using Ni@NC as the anode catalyst illustrates steady performance for more than 200 h, while the Ni/C cell fails within 7 h. The current density loss is less than 10% by feeding H 2 with 100 ppm of CO for 24 h, which is much better than those using Pt/C or Ni/C. The anti-poisoning feature is attributed to the block effect of the NC shell, while the defects allow the permeation of H 2 , thus catalyzing the hydrogen oxidation reaction. [Display omitted] • N-doped carbon encapsulated nickel nanoparticles (Ni@NC) as durable HOR catalysts. • Ni@NC shows high tolerance to the contaminant, such as CO, S2− and SCN−. • Stable and anti-CO poisoning fuel cell has been fabricated using Ni@NC as anode. • The NC nanolayers served as selectively permeable layer to block the toxicants. [ABSTRACT FROM AUTHOR]

To achieve practical application of fuel cell, it is vital to develop highly efficient and durable Pt‐free catalysts. Herein, we prepare atomically dispersed ZnNC catalysts with Zn‐Pyrrolic‐N4 moieties and abundant mesoporous structure. The ZnNC‐based anion‐exchange membrane fuel cell (AEMFC) presents an ultrahigh peak power density of 1.63 and 0.83 W cm−2 in H2‐O2 and H2‐air (CO2‐free), and also exhibits long‐term stability with more than 120 and 100 h for H2‐air (CO2‐free) and H2‐O2, respectively. Density functional calculations further unveil that the Zn‐Pyrrolic‐N4 structure is the origin of high activity of as‐synthesized ZnNC catalyst, while the Zn‐Pyridinic‐N4 moiety is inactive for oxygen reduction reaction (ORR), which successfully explain the puzzle why most Zn‐metal‐organic framework ‐derived ZnNC catalysts in previous reports did not present good ORR activity because of their Zn‐Pyridinic‐N4 moieties. This work offers a new route for speeding up development of AEMFCs. [ABSTRACT FROM AUTHOR]

To achieve practical application of fuel cell, it is vital to develop highly efficient and durable Pt‐free catalysts. Herein, we prepare atomically dispersed ZnNC catalysts with Zn‐Pyrrolic‐N4 moieties and abundant mesoporous structure. The ZnNC‐based anion‐exchange membrane fuel cell (AEMFC) presents an ultrahigh peak power density of 1.63 and 0.83 W cm−2 in H2‐O2 and H2‐air (CO2‐free), and also exhibits long‐term stability with more than 120 and 100 h for H2‐air (CO2‐free) and H2‐O2, respectively. Density functional calculations further unveil that the Zn‐Pyrrolic‐N4 structure is the origin of high activity of as‐synthesized ZnNC catalyst, while the Zn‐Pyridinic‐N4 moiety is inactive for oxygen reduction reaction (ORR), which successfully explain the puzzle why most Zn‐metal‐organic framework ‐derived ZnNC catalysts in previous reports did not present good ORR activity because of their Zn‐Pyridinic‐N4 moieties. This work offers a new route for speeding up development of AEMFCs. [ABSTRACT FROM AUTHOR]

The microstructure of an electrode plays a critical role in the electrochemical performance of lithium‐ion batteries, including the energy and power density. Using a micrometer‐scale Wadsley–Roth phase TiNb2O7 active material with Li intercalation chemistry as a model system, the relationship between electrochemical performance and microstructure of calendared electrodes with same mass loading but different electrode parameters is studied by both experimental investigation and theoretical modeling, providing a paradigm of calendaring‐driven electrode microstructure for balanced battery energy density and power density. Along with the reduction in porosity, ion and electron diffusion distance decreases, which is beneficial for charge transfer and rate capability. Nevertheless, the narrowed ion diffusion pathway increases the resistance for ion diffusion. The rate capability, volumetric capacity, and materials utilization are thus predominantly restricted by the microstructures of the electrode, providing fundamental insights into electrode microstructure design for different applications. As an example, an optimized TiNb2O7 electrode with compaction density of ≈2.5 g cm‐3 and mass loading of ≈8.5 mg cm‐2 provides the highest specific charge capacity of 271.3 mAh g‐1 at 0.2 C in half cell configuration and 70.4% capacity retention at 6 C in full configuration, enabling balanced energy density and power density of batteries. [ABSTRACT FROM AUTHOR]

Understanding historical drought changes is critical to water resource management, vegetation growth, and human life in arid regions with vulnerable and sensitive ecological environments. Based on the Schrenk spruce (Picea schrenkiana) sampled from the whole Tianshan Mountains located northwestern China, we developed a tree-ring chronology to study the dry–wet changes through multiple sites sampling. The results showed the stable significantly positive response of tree-ring width chronology to the standardized precipitation and evapotranspiration index (SPEI) in current April and May, indicating that the tree-ring of Schrenk spruce contained the stronger signal of drought variation at the beginning of the growing season. Therefore, we reconstructed the SPEI from 1735 to 2016 in the study regions with 55.1% of the explained variance of reconstruction equation for 1960–2016, which verified the high accuracy of the reconstructed results. Droughts had alternated over the past three centuries with 14 distinct dry and wet periods. Analyzing the 282-year reconstructed drought showed a significant tendency to become wet for the study regions, which were also well correlated with historical droughts and volcanic eruptions events. The SPEI in the study regions was influenced mainly by large-scale atmospheric–oceanic variability with spectral analysis (MTM) revealing some significant low-frequency periods (53.7–78.7, 15.6–16.7, 7.7–8.2, 5.2–5.3, 3.7–3.9, and 2.1–2.2 years). In particular, the HYSPLIT model proved that the westerly circulation was the driving force of the dry–wet changes in the Tianshan Mountains and that the water vapor originated mainly from the North Atlantic. [ABSTRACT FROM AUTHOR]

The increasing demand of rare earth elements in agriculture and industry raises the potential environmental pollution with their inevitable toxicity and biological accumulation. It is necessary to develop an efficient and low-cost technique to effectively remove rare earth elements. N-doped carbon dots (CDs) were green-synthesized using one-pot domestic microwave oven and novel alginate composite (ALG@CDs) beads were fabricated by embedding the N-doped CDs into pure alginate hydrogel beads. The synthetic materials were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and zeta potential measurement. The ALG@CDs beads could effectively adsorb rare earth elements from aqueous solutions. Taking the adsorption of rare earth element Gd (III) as an example, initial concentration, adsorbent dosage, pH, temperature and contact time were optimized. The adsorption isotherms and kinetics fitted to Langmuir isotherm model (R2 > 0.9991) and pseudo-second-order kinetic model (R2 = 0.9918), respectively. The adsorption capacity of ALG@CDs-3 (201.21 mg/g) for Gd (III) was much higher than that of bare ALG beads (124.38 mg/g) according to the maximum theoretical adsorption capacity of Langmuir model. Competitive adsorption results indicated that ALG@CDs beads had stronger affinity to Gd (III) than to Al (III), Co (II), Ni (II), Zn (II), and Mg (II). The adsorbent could be easily collected and reused for five adsorption-regeneration cycles. The results indicated that the fabricated ALG@CDs beads are the promising materials for adsorption or enrichment of rare earth elements from waste water. [ABSTRACT FROM AUTHOR]

The CO 2 -in-water (C/W) microemulsion was formed when the pressure of CO 2 was above 4.0 MPa and has been investigated in-situ via high-pressure UV/vis spectra. The spherical mesoporous silica was successfully synthesized in CO 2 -induced microemulsion. Uniform spherical silica with a diameter of 102 ± 15 nm can be obtained by using C/W microemulsion as a template. It was observed that the BET area and pore volume of the spherical silica were enlarged with increasing the pressure of CO 2 . Moreover, Pd nanoparticles (Pd NPs) were encapsulated inside the spherical mesoporous silica through one-pot approach. Owing to the particular core–shell structure, this catalyst showed excellent recyclability in the Suzuki coupling reaction when compared with conventional Pd/SiO 2 and Pd/C catalysts. The new strategy can be extended as a general approach to prepare other metal nanoparticles encapsulated in spherical mesoporous silica. [ABSTRACT FROM AUTHOR]

A tungsten peroxo complex stabilized by the bidentate picolinato ligand has been synthesized and then immobilized successfully on imidazole-functionalized silica. The immobilized tungsten-based catalyst was employed as an efficient catalyst for the one-pot synthesis of β-alkoxy alcohols from olefins and methanol with H2O2. Regarding the catalyst evaluation and the results of characterization by the various methods, it was demonstrated that the immobilization of tungsten peroxo complex was highly temperature-dependent. The tungsten peroxo complex can dissociate and diffuse into the liquid phase at reaction temperature, resulting in a homogeneous reaction. Nevertheless, the catalytically active species was anchored on the imidazole-functionalized silica by hydrogen bonding as the temperature was lowered to 0 °C after the reaction, which thus offered a highly effective approach for recycling the catalyst for consecutive cycles. In addition, various olefins can be converted to the corresponding β-alkoxy alcohols with good conversion and selectivity under relative mild conditions by H2O2. [ABSTRACT FROM AUTHOR]

A series of peroxoniobate salts of amidine and guanidine were prepared successfully and utilized as halogen-free catalysts for the synthesis of cyclic carbonates from epoxides and CO2 under solvent-free and halide-free conditions. The reaction could be performed with high activity and selectivity with the assistance of the environmentally benign catalysts. CO2 could be chemically activated through an organic base dissociated from the parent catalyst during the reaction, while niobate anions played a crucial role in immobilizing catalytically active organic cations and thus improving the recyclability of the catalyst. The structural characterization of the catalysts indicated that peroxoniobate anions had undergone structural changes and were transformed into more stable niobate anions in the consecutive recycles. It was shown that the catalyst could be reused with high conversion and selectivity by a really straightforward process. Furthermore, this protocol was found to be applicable to a variety of epoxides producing the corresponding cyclic carbonates in high conversion and selectivity. The process herein represents a simple, ecologically friendly and efficient route for CO2 chemical fixation into high value chemicals. [ABSTRACT FROM AUTHOR]

Ultrafast and facile microwave-assisted synthesis of guanine-derived carbon dots for highly sensitive and selective detection of Ag+. • A green microwave method was developed for synthesis of guanine-derived carbon dots. • A sensitive and selective fluorescent sensing of Ag+ with LOD of 90 nM was realized. • The strong interaction of guanine-Ag+ was crucial for Ag+ sensing confirmed by DFT calculations. • The carbon dots were capable for detecting Ag+ in real water sample. In this work, a simple and green synthetic approach of novel guanine decorated carbon dots (G-CDs) using guanosine 5′-monophosphate and ethylenediamine through a domestic microwave oven was established for the first time. The as-prepared fluorescent G-CDs were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, UV–vis spectroscopy, and fluorescence spectroscopy. The obtained fluorescent G-CDs with a uniform morphology had desirable functional groups and excellent optical performances. Furthermore, the fluorescence intensity of G-CDs was remarkably quenched by Ag+ than that of other nucleotides-derived CDs. The density functional theory calculations were performed to confirm that the strong interaction of guanine-Ag+ was responsible for the remarkable fluorescence response of G-CDs towards Ag+. In addition, as a label-free fluorescence probe, the G-CDs displayed a good linear detection for highly selective Ag+ sensing over the range of 0–80 μM with the low detection limit of 90 nM. Therefore, the proposed G-CDs had the capacity for Ag+ detection in the real samples. [ABSTRACT FROM AUTHOR]