Ferrihydrite transformation impacted by coprecipitation of lignin: Inhibition or facilitation?

Lignin is a common soil organic matter that is present in soils, but its effect on the transformation of ferrihydrite (Fh) remains unclear. Organic matter is generally assumed to inhibit Fh transformation. However, lignin can reduce Fh to Fe(II), in which Fe(II)-catalyzed Fh transformation occurs. Herein, the effects of lignin on Fh transformation were investigated at 75°C as a function of the lignin/Fh mass ratio (0-0.2), pH (4-8) and aging time (0-96 hr). The results of Fh-lignin samples (mass ratios = 0.1) aged at different pH values showed that for Fh-lignin the time of Fh transformation into secondary crystalline minerals was significantly shortened at pH 6 when compared with pure Fh, and the Fe(II)-accelerated transformation of Fh was strongly dependent on pH. Under pH 6, at low lignin/Fh mass ratios (0.05-0.1), the time of secondary mineral formation decreased with increasing lignin content. For high lignosulfonate-content material (lignin:Fh = 0.2), Fh did not transform into secondary minerals, indicating that lignin content plays a major role in Fh transformation. In addition, lignin affected the pathway of Fh transformation by inhibiting goethite formation and facilitating hematite formation. The effect of coprecipitation of lignin on Fh transformation should be useful in understanding the complex iron and carbon cycles in a soil environment.

Design of Bifunctional Cu-SSZ-13@Mn2Cu1Al1Ox Core-Shell Catalyst with Superior Activity for the Simultaneous Removal of VOCs and NOx

Synchronous control of volatile organic compounds (VOCs) and nitrogen oxides (NOx) is of great importance for ozone and PM2.5 pollution control. Balancing VOC oxidation and the NH3-SCR reaction is the key to achieving the simultaneous removal of these two pollutants. In this work, a vertically oriented Mn2Cu1Al1Ox nanosheet is grown in situ on the surface of Cu-SSZ-13 to synthesize a core-shell bifunctional catalyst (Cu-SSZ-13@Mn2Cu1Al1Ox) with multiple active sites. The optimized Cu-SSZ-13@Mn2Cu1Al1Ox catalyst delivered excellent performance for the simultaneous removal of VOCs and NOx with both 100% conversion at 300 °C in the presence of 5% water vapor. Physicochemical characterization and density functional theory (DFT) calculations revealed that Cu-SSZ-13@Mn2Cu1Al1Ox possesses more surface acidity and oxygen vacancies. The charge transfer between the core and shell is the intrinsic reason for the improved activity for both VOC and NOx removal. The molecular orbital theory is used to explain the different adsorption energies due to the different bonding modes between the core-shell and mixed individual catalysts. This work provides a novel strategy for designing efficient catalysts for the simultaneous removal of VOCs and NOx or other multiple pollutants.

Intercalation vs Adsorption Strategies of Myo-Inositol Hexakisphosphate into Zn-Fe Layered Double Hydroxide: A Tiff between Anion Exchange and Coprecipitation

Myo-inositol hexakisphosphates (IHPs) or phytates are the most abundant organic phosphates having the potential to serve as a phosphorus reserve in soil. Understanding the fate of IHP interaction with soil minerals tends to be crucial for its efficient storage and utilization as a slow-release organic phosphate fertilizer. We have systematically compared the effective intercalation strategy of a phytate onto Zn-Fe layered double hydroxide (LDH) acting as storage/carrier material through coprecipitation and anion exchange. Powder X-ray diffraction, X-ray photoelectron spectroscopy, elemental analysis, thermogravimetric analysis, FTIR spectra, and molecular modeling demonstrated the formation of phytate-intercalated Zn-Fe LDH through coprecipitation with a maximum loading of 41.34% (w/w) in the pH range of ∼9-10 in a vertical alignment through monolayer formation. No intercalation product was obtained from the anion exchange method, which was concluded based on the absence of shifting in the XRD (003) peak. A change in the zeta potential values from positive to negative and subsequent increase in solution pH, with decreasing phytate concentration, are suggestive of adsorption of IHP onto the LDH surface. The batch adsorption data were best fitted with Langmuir isotherm equation and followed the pseudo-second-order kinetic model. The maximum adsorption capacity was found to be 45.87 mg g-1 at a temperature of 25 ± 0.5 °C and pH 5.63.

Preparation of carbon quantum dots from ionic liquid modified biomass for the detection of Fe3+ and Pd2+ in environmental water

A new type of green carbon quantum dots (ILB-CQDs) was prepared by hydrothermal method using ionic liquid as a modifier and grape skin as carbon source, and was obtained from hydrogen-bonded lattice structure ionic liquid preparation, which makes the CQDs in a ring-like stable structure with a stability period of more than 90 day. There is also the catalytic effect of the ionic liquid on cellulose, which makes the prepared CQDs show good advantages, such as uniform particle size, high quantum yield (26.7%), and very good fluorescence performance. This is a smart material for the selective detection of Fe³⁺ and Pd²⁺. It has a detection limit of 0.001 nM for Fe³⁺ and 0.23 µM for Pd²⁺ in pure water. It has a detection limit of 3.2 nmol/L for Fe³⁺ and 0.36 µmol/L for Pd²⁺ in actual water, both of which meet the requirements of WHO drinking water standards. And there is to achieve more than 90% of water restoration effect.

Activation of peroxymonosulfate by palygorskite-mediated cobalt-copper-ferrite nanoparticles for bisphenol S degradation: Influencing factors, pathways and toxicity evaluation

Peroxymonosulfate (PMS)-based advanced oxidation process is considered a potential technology for water treatment. Here, palygorskite (PAL)-mediated cobalt-copper-ferrite nanoparticles (16%-CoCu_0.4Fe_1·6O₄@PAL, donated as 16%-CCFO@PAL) were employed for PMS activation to remove bisphenol S (BPS). BPS degradation was greater than 99% under the optimal conditions within 25 min, on which the effects of various influencing factors were explored. The adsorption dissociation energy of PMS over 16%-CCFO@PAL was -6.27 eV, which was lower than that of the Cu-free catalyst (-6.15 eV), demonstrating the excellent catalytic ability of 16%-CCFO@PAL. The efficient catalytic ability of 16%-CCFO@PAL was also verified in real water samples. The oxidation intermediates were identified and their generations were systematically analyzed by DFT calculations. The possible degradation pathways of BPS were proposed and the toxicity of products was predicted. BPS affected the normal development of zebrafish embryos and the levels of sex hormone in adult male zebrafish, and was harmful to the tissues, such as testis, liver, and intestine of zebrafish. The 16%-CCFO@PAL/PMS process can effectively reduce the toxicity of BPS-polluted water. This study paves the way for the real application of 16%-CCFO@PAL/PMS oxidation process and provides a new perspective for the evaluation of water toxicity.

Effect of surface wettability on the interfacial adhesion of a thermosetting elastomer on glass

Interfacial adhesion dictates properties and performance of both composites and adhesively bonded structures. Weak adhesion at the interfaces of polymer composites leads to void formation and debonding, which adversely affect composite structural integrity and mechanical performance. This work investigated the relationship between surface wettability and interfacial fracture energy with the goal of tailoring interfacial adhesion within polymer composites. A series of model functionalized surfaces was created using silane coupling agents with different organo-functionalities to alter surface wettability. Based on the analysis of interfacial fracture energy between a thermosetting elastomeric polymer network and model surfaces, interfacial adhesion was found to be positively correlated to resin wettability. The results provide a fast and simple approach to screen different material combinations for the development of novel polymeric composites and adhesively bonded structures with tailorable adhesion.

Interfacial adhesion is postively correlated with resin wettability.

Chemical characterization of red cells from the black sea urchin Arbacia lixula by X-ray photoelectron spectroscopy

Red spherula cells (RSC) from sea urchin coelomic fluid have attracted great interest for their specific and intriguing properties, such as for example antimicrobial activities and immune response, that probably tie in with their red characteristic pigments. Although to date different studies have been reported aimed to chemically characterize their pigments extracted from the cells, few data are available about the chemical characterization of the cell surface. In this work, a systematic chemical characterization of the RSC surface by X-ray photoelectron spectroscopy (XPS) analysis is described. The results were compared with data on colorless cells from the same coelomic fluid sample. Our observations evidenced that the two cell types were characterized by the presence of different chemical functional groups. In particular, the colorless cells are dominated by the presence of alkyl, alcohol, amide, and carboxyl groups in accordance with other similar cell types, enriched in Na⁺ and Cl⁻ ions. Traces of elements like S (sulphonates) and P (phosphates) are also present. On the other hand, the RSC in addition to the alkyl groups show a reduction in the content of amide groups, accompanied by the anomalous presence of keto-enolic groups that probably can be associated with the presence of quinones/hydro-quinones from red pigments. A chemical enrichment in elements such as Cl⁻ and Mg²⁺ and sulphate groups (–R–O–SO₃⁻), as well as the presence of sulphides and phosphates traces, is evident. The absence of carbonate groups is also observed in both cell populations, confirming the absence of sodium and magnesium carbonate salts. No traces of toxic elements (i.e., heavy metals) have been revealed.

Red spherula cells from sea urchin coelomic fluid have attracted great interest for their specific and intriguing properties, such as antimicrobial activities and immune response, that probably tie in with their red characteristic pigments.

Supramolecular Anchoring Strategy for Facile Production of Ruthenium Nanoparticles Embedded in N-Doped Mesoporous Carbon Nanospheres for Efficient Hydrogen Generation

Because of the favorable mass transport and increased available active sites, the rational design and preparation of porous carbon structures are essential but still challenging. Herein, a novel and facile supramolecular anchoring strategy was developed to achieve the embedding of ruthenium (Ru) nanoparticles in N-doped mesoporous carbon nanospheres through pyrolyzing the precursor formed by coordination assembly between metal ions and zinc gluconate (G(Zn)). Featuring rich hydroxyl groups, the G(Zn) can effectively chelate Ru³⁺ via metal-oxygen bonds to form 3D supramolecular nanospheres, and meanwhile, mesopores in carbon nanospheres were expanded after subsequent pyrolysis thanks to the volatilization of zincic species at high temperature. As a demonstration, the best-performing catalyst displayed extraordinary activity for the hydrogen evolution reaction (HER) with a small overpotential of 43 mV versus reversible hydrogen electrode (vs RHE) at 10 mA/cm² and a Tafel slope of 39 mV/dec, which was superior to that of commercial Pt/C in alkaline medium. Theoretical calculations revealed that the catalytic activity was significantly promoted by the strong electronic coupling between Ru nanoparticles and N-doped porous carbon, which increased the electron transfer capability and facilitated the adsorption and dissociation of H₂O to realize an efficient HER.

Selective Pattern Growth of Atomically Thin MoSe2 Films via a Surface-Mediated Liquid-Phase Promoter

Two-dimensional transition metal dichalcogenides (TMDs) offer numerous advantages over silicon-based application in terms of atomically thin geometry, excellent opto-electrical properties, layer-number dependence, band gap variability, and lack of dangling bonds. The production of high-quality and large-scale TMD films is required with consideration of practical technology. However, the performance of scalable devices is affected by problems such as contamination and patterning arising from device processing; this is followed by an etching step, which normally damages the TMD film. Herein, we report the direct growth of MoSe₂ films on selective pattern areas via a surface-mediated liquid-phase promoter using a solution-based approach. Our growth process utilizes the promoter on the selective pattern area by enhancing wettability, resulting in a highly uniform MoSe₂ film. Moreover, our approach can produce other TMD films such as WSe₂ films as well as control various pattern shapes, sizes, and large-scale areas, thus improving their applicability in various devices in the future. Our patterned MoSe₂ field-effect transistor device exhibits a p-type dominant conduction behavior with a high on/off current ratio of ∼10⁶. Thus, our study provides general guidance for direct selective pattern growth via a solution-based approach and the future design of integrated devices for a large-scale application.

Electrochemical and Surface Characterization Study on the Corrosion Inhibition of Mild Steel 1030 by the Cationic Surfactant Cetrimonium Trans-4-hydroxy-cinnamate

Effective corrosion inhibition of mild steel 1030 at 0.01 M NaCl concentration was achieved by the use of the nontoxic surfactant salt cetrimonium trans-4-hydroxy-cinnamate (CTA-4OHcinn). Polarization analysis on the steel samples immersed for 24 h in the control and CTA-4OHcinn-containing solutions shows the development of a passivation potential that is more obvious at higher inhibitor concentrations along with a maximum inhibition efficiency of 97.8%. Electrochemical impedance spectroscopy (EIS) pinpoints the effect of the inhibitor on the corroding regions of the metal surface, showing an increase in the local electric resistance and conversely a decrease in the local capacitance, which indicates that the charge transfer in the corroding regions is being hindered by a deposition process. This is consistent with scanning electron microscopy (SEM) images, showing the presence of a porous oxide matrix that fills localized corrosion sites on the metal surface after 24 h of immersion in a 0.01 M NaCl + 10 mM inhibitor solution. Additionally, SEM analysis also shows the formation of an organic film surrounding the defects that is able to shield chloride attack. As a result of diffusion of chloride from the defects below the protective film, filiform corrosion can be seen. Time-resolved impedance analysis over the first 120 min of immersion in the control and inhibitor solution shows that significant inhibitor protection does not take place immediately and there is a lag phase in the first 50 min of immersion, suggesting that early localized corrosion drives further adsorption of inhibitor micelles on the metal surface. This is in agreement with X-ray photoelectron spectroscopy (XPS) analysis, which indicates a complete surface coverage over the first 2 h of immersion in a concentrated inhibitor solution. XPS also shows the heterogeneity of the film, where some parts are poorly covered, revealing the underlying surface containing iron.

Electrochemical synthesis of a new Bi(iii) complex by anodic oxidation of Bi in an aqueous solution of 4-toluenesulfonic acid

A new complex with a composition [Bi₆O₄(OH)₄](C₇H₇SO₃)₆ is formed on a bismuth plate via electrochemical synthesis at 1.0 V anodic polarization in 0.5 M p-toluenesulfonic acid.

Porphyrin functionalized bismuth ferrite for enhanced solar light photocatalysis

In this work, multiferroic bismuth ferrite (BFO) was functionalized with meso-tetraphenylporphine-4,4',4'',4'''-tetracarboxylic acid (TCPP). This new hybrid organic-inorganic material shows an enhanced photocatalytic activity for the degradation of organic dyes as it combines the properties of BFO which is an efficient visible light photocatalyst with peculiar porphyrin absorption in visible light. The anchoring of TCPP to the OH-terminations of the BFO surface through its carboxylic tethering groups was demonstrated using X-ray photoelectron spectroscopy and FT-IR spectroscopy. The photocatalytic activity of the material was also demonstrated through the photocatalytic degradation of Methylene Blue (MB) and Rhodamine-B (Rhd-B) in water under simulated solar light illumination. The TCPP molecules anchored to BFO slightly decrease (∼0.06 eV) the bandgap energy of the system and act as new catalytic centres, thus improving its photocatalytic activity. A photodegradation mechanism was also proposed. This new material is reusable and stable, as it maintains an unmodified photo-activity after several MB discoloration runs.

Single-step synthesis of polychromatic carbon quantum dots for macroscopic detection of Hg2

Two kinds of carbon quantum dots (CQDs), having luminous peaks at 480 and 525 nm, were obtained by a single-step hydrothermal method. The detection of Hg²⁺ by two kinds of carbon dots was further explored. In order to compensate for the weak luminescence of blue carbon dots (480 nm) and low sensitivity of green carbon dots (525 nm), mixed carbon dots were examined for Hg²⁺ detection. The mixed carbon dots showed a better detection of Hg²⁺ ions. Low detection limit of 0.05 μM was found to be in the range of 0-1.0 μM of Hg²⁺. Moreover, in this range, the change of fluorescence intensity can be clearly seen under the ultraviolet lamp, which will be conducive for the practical application of detecting mercury ions with carbon dots.

Enhancing the sensitivity of a surface plasmon resonance-based optical sensor for zinc ion detection by the modification of a gold thin film

Surface plasmon resonance (SPR) sensors as novel optical sensors for the detection of a variety of analytes have been receiving increasing attention and their sensitivity has become the research hotspot recently. In this study, the sensitivity of an SPR optical sensor was enhanced by modifying a gold thin film with a nanocrystalline cellulose (NCC)-based material for zinc ion (Zn2+) detection that exists in the environment due to industrial processing. By replacing the gold thin film with a novel modified-gold thin film, Zn2+ can be detected from the range of 0 to 10 ppm using SPR. It is believed that the Zn2+ may interact with the negative charge molecules that exist on the modified-gold thin film, and this was confirmed via X-ray photoelectron spectroscopy (XPS). Moreover, this modified-gold-SPR has a high sensitivity of 1.892° ppm-1 up to 0.1 ppm with an enhanced detection of Zn2+ as low as 0.01 ppm. The SPR results also followed the Langmuir isotherm model with a binding affinity of 1.927 × 103 M-1, which further confirmed the sensitivity of the SPR sensor. In addition, using the modified-gold thin film, SPR has a higher affinity towards Zn2+ compared to other metal ions, i.e. Ni2+, Fe2+, Cr2+, Mn2+, and Co2+.

Carbon Dots Exhibiting Concentration-Dependent Full-Visible-Spectrum Emission for Light-Emitting Diode Applications

Carbon dots (CDs) that exhibit emission over the whole visible spectrum are desired for use in light-emitting diodes (LEDs). Here, CDs displaying tunable fluorescence over the whole visible region are synthesized. Different concentrations of CDs are uniformly dispersed in epoxy resin and coated on 405 nm LED chips to obtain monochrome blue, cyan, green, yellow, red, and deep red LEDs that yield a color gamut covering 99.4% of the National Television Standards Committee (NTSC) standard. These monochrome LEDs display similar high stability. Furthermore, warm and neutral white LEDs are produced by coating cyan- and red-emitting CD layers on 405 nm LED chips, achieving color-rendering indexes (CRIs) of 96.4 and 96.6, respectively. Two fluorescent conversion layers derived from one material at different concentrations simplify the preparation of high-CRI white LEDs. The uniform weak changes of the cyan and red photoluminescence peaks during operation ensure the high stability of these CD-based white LEDs. This research provides a new avenue to develop low-cost, easy-to-prepare CDs with tunable emission colors as alternative phosphors for LED-based high-performance displays and lighting.

Structural Memory Effect of Mg-Al and Zn-Al layered Double Hydroxides in the Presence of Different Natural Humic Acids: Process and Mechanism

The structural memory effect of layered double hydroxides (LDHs) is one of the important reasons for their extensive use in environmental remediation. In this study, humic acid (HA) was extracted from black soil and sediments and characterized to determine their structures. The regeneration mechanisms of calcinated LDHs (CLDHs) including different divalent metals (Mg-CLDH and Zn-CLDH) in deionized water and different HA solutions were carefully elucidated, and the reasons for the behavior differences in the two materials were explained. The presence of the HAs significantly increased the dissolution rate of Mg²⁺ ions from Mg-CLDHs and subsequent regeneration of Mg-LDH. Because of the diverse functional groups in the HAs, these groups were complexed with metallic ions such as Mg²⁺ on the surface of Mg-CLDH in the beginning. During the process, the HAs adsorbed the regenerated LDHs on the surfaces. Therefore, the crystallinity, morphology, and specific surface area of the regenerated Mg-LDH significantly changed, especially in the presence of high concentrations of HA. In the case of Zn-CLDH, the regeneration rate of the LDH increased in the presence of HA, but the surface of Zn-CLDH was covered with regenerated Zn-LDH and HA. Then, the inside of the particles could not transform to LDH, leading to poor crystallinity and a significant increase in the ZnO content of the HA system.

Editable TiO2 Nanomaterial-Modified Paper in Situ for Highly Efficient Detection of Carcinoembryonic Antigen by Photoelectrochemical Method

In this work, a versatile photoelectrochemical paper-based sensor based on N-carbon dots/TiO₂-Pt-modified paper in situ is developed for sensitive detection of carcinoembryonic antigen (CEA) in clinical serum samples. Interconnected cellulose fibers on paper provide a porous, 3D, and flexible substrate for photoelectrochemical sensing. In situ modification of N-carbon dots/TiO₂-Pt with editable structures on paper significantly increases the conductivity, widens the adsorption range, and enhances the photoelectrochemical ability, which enables the higher sensitivity and flexibility compared with traditional rigid sensors. On the basis of this novel protocol, a miniaturized and portable origami device realizes the CEA determination with a low detection limit of 1.0 pg mL^-1 and a wide linear range from 0.002 to 200 ng mL^-1. Thanks to the good biocompatibility, the paper-based device provides a new avenue for the detection of CEA on the cell surface which is promising for portable diagnostics in early tumor warning.

Improvement of the Cathode Electrolyte Interphase on P2-Na2/3Ni1/3Mn2/3O2 by Atomic Layer Deposition

Atomic layer deposition (ALD) is a commonly used coating technique for lithium ion battery electrodes. Recently, it has been applied to sodium ion battery anode materials. ALD is known to improve the cycling performance, Coulombic efficiency of batteries, and maintain electrode integrity. Here, the electrochemical performance of uncoated P2-Na_2/3Ni_1/3Mn_2/3O₂ electrodes is compared to that of ALD-coated Al₂O₃ P2-Na_2/3Ni_1/3Mn_2/3O₂ electrodes. Given that ALD coatings are in the early stage of development for NIB cathode materials, little is known about how ALD coatings, in particular aluminum oxide (Al₂O₃), affect the electrode-electrolyte interface. Therefore, full characterizations of its effects are presented in this work. For the first time, X-ray photoelectron spectroscopy (XPS) is used to elucidate the cathode electrolyte interphase (CEI) on ALD-coated electrodes. It contains less carbonate species and more inorganic species, which allows for fast Na kinetics, resulting in significant increase in Coulombic efficiency and decrease in cathode impedance. The effectiveness of Al₂O₃ ALD coating is also surprisingly reflected in the enhanced mechanical stability of the particle which prevents particle exfoliation.

A green one-pot synthesis of nitrogen and sulfur co-doped carbon quantum dots for sensitive and selective detection of cephalexin

The article reports a simple, economic, and green method for preparing water-soluble, nitrogen and sulfur co-doped carbon quantum dots via a one-step hydrothermal method. Pomegranate juice served as the carbon source, and the L-cysteine provided nitrogen and sulfur. Co-doped carbon dots were characterized by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy techniques. The co-doped carbon dots served as fluorescent probes for sensitive and selective detection of cephalexin. Briefly, the co-doped carbon dot systems showed quenching of photoluminescence intensity in the presence of cephalexin. The decrease of fluorescence intensity made it possible to analyze cephalexin with satisfactory detection limits and linear ranges. The Sterne–Volmer plot showed a linear relationship (R2 = 0.998) between F0/F and the concentration of cephalexin over the range from 0.3 to 10 μmol L−1. The limit of detection (LOD) was estimated to be 1 × 10−7 mol L−1 (at a signal to noise ratio of 3). To validate the applicability, the described method was successfully applied for the detection of cephalexin in human urine and raw milk samples.

Green emission and Ag(+) sensing of hydroxy double salt supported gold nanoclusters

In this paper, a complex of Zn-containing hydroxy double salt (Zn-HDS) supported gold nanoclusters (AuNCs) has been synthesized. The formation of the complex (denoted as the AuNCs/Zn-HDS complex) has been analyzed by Transmission Electron Microscopy (TEM), IR spectroscopy and X-ray Photoelectron Spectroscopy (XPS). It is noteworthy that the AuNCs/Zn-HDS complex emits green fluorescence and the quantum yield is 7.6%. Based on the fluorescence quenching effect, the AuNCs/Zn-HDS complex has been employed for the sensitive detection of Ag(+) and the limit of detection is 2.32 nM. The mechanisms of fluorescence generation and quenching are discussed in detail.

Thermal catalytic oxidation of octachloronaphthalene over anatase TiO2 nanomaterial and its hypothesized mechanism

As an environmentally-green technology, thermal catalytic oxidation of octachloronaphthalene (CN-75) over anatase TiO₂ nanomaterials was investigated at 300 °C. A wide range of oxidation intermediates, which were investigated using various techniques, could be of three types: naphthalene-ring, single-benzene-ring, and completely ring-opened products. Reactive oxygen species on anatase TiO₂ surface, such as O₂^−• and O²⁻, contributed to oxidative degradation. Based on these findings, a novel oxidation degradation mechanism was proposed. The reaction at (101) surface of anatase TiO₂ was used as a model. The naphthalene-ring oxidative products with chloronaphthols and hydroxyl-pentachloronaphthalene-dione, could be formed via attacking the carbon of naphthalene ring at one or more positions by nucleophilic O²⁻. Lateral cleavage of the naphthalene ring at different C₁-C₁₀ and C₄-C₉, C₁-C₂ and C₄-C₉, C₁-C₂ or and C₃-C₄ bond positions by electrophilic O₂^−• could occur. This will lead to the formation of tetrachlorophenol, tetrachloro-benzoic acid, tetrachloro-phthalaldehyde, and tetrachloro-acrolein-benzoic acid, partially with further transformation into tetrachlorobenzene-dihydrodiol and tetrachloro-salicylic acid. Unexpectedly, the symmetric half section of CN-75 could be completely remained with generating the intricate oxidative intermediates characteristically containing tetrachlorobenzene structure. Complete cleavage of naphthalene ring could produce the ring-opened products, such as formic and acetic acids.

A novel electrochemiluminescence sensor based on Ru(bpy)₃²⁺/N-doped carbon nanodots system for the detection of bisphenol A

A novel Ru(bpy)3(2+)-based electrochemiluminescence (ECL) sensing platform, using N-doped carbon nanodots (N-C dots) as co-reactant, was established for the sensitive and selective detection of bisphenol A (BPA). N-C dots not only could enhance the ECL signal, but also significantly improved the reproducibility and stability of Ru(bpy)3(2+) ECL system. The developed ECL sensing system was sensitive to detect BPA based on its efficient quenching effect on Ru(bpy)3(2+)/N-C dots. The N-C dots-enhanced ECL mechanism and BPA-quenched ECL mechanism were investigated. Under the optimum conditions, the inhibited ECL intensity was in good linear relationship versus the concentration of BPA in the range of 0.03-1.0 μM with the detection limit of 10 nM. The relative standard deviation (RSD) for 25 successive measurements with one sensor was 1.1% and for eight different sensors was 2.5%, respectively. The fabricated sensing platform was successfully applied for the detection of BPA in baby bottle and nipple, and relatively satisfactory recoveries were obtained.

Novel morphology-controlled hierarchical core@shell structural organo-layered double hydroxides magnetic nanovehicles for drug release

Novel hierarchical core@shell structured salicylate (SA) intercalated ZnAl-LDH (layered double hydroxides) magnetic nanovehicles were obtained via a special double-drop coprecipitation strategy assembling organo-ZnAl-LDH nanocrystals onto the surface of Fe3O4 submicrospheres (∼480 nm) from cheap aspirin and Zn- and Al-nitrates in alkaline solutions. The obtained Fe3O4@SA-LDH-r nanovehicles exhibit varied morphologies with hexagonal LDH ab-face horizontal, vertical, and vertical/slant/horizontal to the surfaces of Fe3O4 upon proper mass ratio (r) of Zn-salt to Fe3O4 from 1.93 to 7.71 in a low supersaturation system and possess moderate drug loadings and strong superparamagnetism. An in vitro release study reveals that under "no MF" mode (without external magnetic field) the SA release exhibits the higher accumulated release amount and smaller half-life (t0.5) for Fe3O4@SA-LDH-3.85 (41.2%, 1.63 min) and Fe3O4@SA-LDH-7.71 (51.1%, 1.66 min) probably owing to their mainly vertical LDH orientations, while the dramatically reduced SA release (10.0%) and greatly elongated t0.5 (25.6 min) for Fe3O4@SA-LDH-1.93 may be due to its relatively stronger host-guest interaction and compact horizontally oriented LDH shell stack. Under "MF on" mode, all the magnetic samples show a detectable reduced SA release owing to the particle-particle interactions among the magnetic nanovehicles. The kinetic fittings show that the release processes of all the samples involve the bulk and surface diffusion. The SA release from Fe3O4@SA-LDH-1.93 is mainly determined by the interparticle diffusion among the horizontally oriented LDH shell nanocrystals while those of Fe3O4@SA-LDH-3.85 and Fe3O4@SA-LDH-7.71 mainly involve the interlayer intraparticle diffusion between LDHs layers due to their largely vertical LDH shell nanocrystals.

Economical, green synthesis of fluorescent carbon nanoparticles and their use as probes for sensitive and selective detection of mercury(II) ions

The present article reports on a simple, economical, and green preparative strategy toward water-soluble, fluorescent carbon nanoparticles (CPs) with a quantum yield of approximately 6.9% by hydrothermal process using low cost wastes of pomelo peel as a carbon source for the first time. We further explore the use of such CPs as probes for a fluorescent Hg(2+) detection application, which is based on Hg(2+)-induced fluorescence quenching of CPs. This sensing system exhibits excellent sensitivity and selectivity toward Hg(2+), and a detection limit as low as 0.23 nM is achieved. The practical use of this system for Hg(2+) determination in lake water samples is also demonstrated successfully.

Hydrothermal treatment of grass: a low-cost, green route to nitrogen-doped, carbon-rich, photoluminescent polymer nanodots as an effective fluorescent sensing platform for label-free detection of Cu(II) ions

Increasing reaction temperature produces photoluminescent polymer nanodots (PPNDs) with decreased particle size and increased quantum yield. Such PPNDs are used as an effective fluorescent sensing platform for label-free sensitive and selective detection of Cu(II) ions with a detection limit as low as 1 nM. This method is successfully applied to determine Cu(2+) in real water samples.