In this study, Liquidambar formosana tree leaves have been used as a renewable biomass precursor for preparing porous carbons (PCs). The PCs were produced by pyrolysis of natural waste of leaves after 10% KOH activation under a nitrogen atmosphere and characterized by a variety of state-of-the-art techniques. The PCs possess a large surface area, micro-/mesoporosity, and functional groups on its surface. A glassy carbon electrode modified with high PCs was explored as an efficient binder-free electrocatalyst material for the voltammetric determination of nitro isomers such as 3-nitroaniline (3-NA) and 4-nitroaniline (4-NA). Under optimal experimental conditions, the electrochemical detection of 3-NA and 4-NA was found to have a wide linear range of 0.2-115.6 and 0.5-120 μM and a low detection limit of 0.0551 and 0.0326 μM, respectively, with appreciable selectivity. This route not only enhanced the benefit from biomass wastes but also reduced the cost of producing electrode materials for electrochemical sensors. Additionally, the sensor was successfully applied in the determination of nitro isomers even in the presence of other common electroactive interference and real samples analysis (beverage and pineapple jam solutions). Therefore, the proposed method is simple, rapid, stable, sensitive, specific, reproducible, and cost-effective and can be applicable for real sample detection. © 2019 American Chemical Society.

Chicken feather-derived high-surface-area porous activated carbon (CFAC) material was prepared using chemical activation. A new composite composed of Ru-Pd nanoparticles supported on CFAC (Ru-Pd@CFAC) has been prepared by microwave-thermal reduction in the presence of the support. Characterization by XRD, Raman, BET, FE-SEM/TEM, FT-IR, TGA, XPS, HAADF-STEM-EDS, H2-chemisorption, H2-TPR, and ICP-AES was used to analyze the catalyst. This catalyst is found to be efficient for the reduction of hexavalent chromium (CrVI), potassium ferricyanide (K3[Fe(CN)6]), 4-nitrophenol (4-NP), and pendimethalin (PDM), at room temperature, and remains stable, even after several repeated runs. Moreover, it showed excellent catalytic activity compared with the monometallic counterparts. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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The multiple sensing capabilities of molybdenum disulfide quantum dots (MoS2 QDs) towards metal ions were scrutinized by tuning their surface functional groups. The MoS2 QDs surface was individually modified with thiol-containing capping agents to form carboxylic-, amine- and thiol-functionalized MoS2 QDs (MoS2/COOH, MoS2/NH2 and MoS2/SH) by the facile hydrothermal method. Each as-prepared QDs exhibits strong excitation wavelength dependent fluorescence behavior. The design of MoS2 QDs based metal ion sensor was implemented based on the fluorescence turn-on mechanism. These MoS2/COOH, MoS2/NH2 and MoS2/SH QDs sensors exhibit superior performance towards the highly selective detection of Co2+, Cd2+ and Pb2+ ions, respectively, due to the varied association of each functional group towards metal ions. The resultant detection limit of Co2+, Cd2+ and Pb2+ was evaluated to be 54.5, 99.6 and 0.84 nM, respectively, and the related fluorescence turn-on mechanism is verified unambiguously. The binding energies were calculated for QDs with metal ions pairs and the results lent support to the determined sensitivity. The as-prepared QDs were also successfully demonstrated to detect the above metal ions in real water samples. While becoming potential candidates in the chemosensors based on the fluorescence probe, these surface modified MoS2 QDs can offer an excellent sensing capability for specific metal ions with extremely high selectivity.

Acid-functionalized mesoporous carbons (AF-MPCs) have been synthesized and used as adsorbents for removal of an azo dye, Eriochrome Black-T (EBT), from aqueous solution. To generate acid surface functionalities, mesoporous carbons (MPCs) were treated with sulfuric acid. Characterization of the samples was analyzed by XRD, Raman spectra, N 2 adsorption-desorption, FE-TEM, TGA, and FT-IR studies. The adsorption studies were carried out under various parameters, such as pH, adsorbent dosage, contact time, initial dye concentration solution temperature, and salt concentration. The results showed that the EBT adsorption onto samples was affected by the pH of solution; the maximum EBT ion adsorption took place at pH 1; and the adsorption uptake was increased with an increase in the initial dye concentration. Moreover, the mechanism of adsorption was investigated using kinetic, diffusion, and isotherm models. The best fit was obtained by the Langmuir model with high correlation coefficients (R 2 = 0.9463) with a maximum monolayer adsorption capacity of 117.0 mg·g -1 . The adsorbed anionic EBT dye molecules were eluted by ethanol solvent with the recovery percentage of 98%. Moreover, this study demonstrates that AF-MPCs can be successfully used as a low-cost adsorbent for the removal of EBT from aqueous solutions. © 2019 American Chemical Society.

Palladium nanoparticles encapsulated in the carbon dots (Pd/C-dots) are demonstrated to play a role of multifunctional nanohybrid in the synergetic applications of sensor and catalysis. The photochemical method is applied to synthesize Pd/C-dots in which Pd nanoparticles (NPs) are dispersedly encapsulated by C-dots layer. The nanohybrid can function as a fluorescent sensor and reductive catalyst, due to the inherent properties of C-dots and Pd NPs, respectively. The Pd/C-dots exhibit a highly selective and sensitive detection toward the nickel (Ni2+) ion with a detection limit of 7.26 × 10−9 m. Moreover, the Ni2+ is detected in MCF-7 live cells signifying the applicability of nanohybrid as a promising sensor. On the other hand, the Pd/C-dots show an excellent catalytic performance in the reduction of 4-nitrophenol and eosin yellow. A plausible mechanism for sensing and catalysis behavior is proposed. The sensor system is designed on the basis of the fluorescence turn-on when Ni2+ interacts with functional groups of the C-dots layer. The activities of catalytic reduction are mainly governed by the Pd NPs and further enhanced when the C-dots layer is incorporated. The Pd/C-dots can serve as a new paradigm for opening a potential trend in the design of multifunctional materials to diverse applications. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Photodissociation of CH2BrI was investigated in search of unimolecular elimination of BrI via a primary channel using cavity ring-down absorption spectroscopy (CRDS) at 248 nm. The BrI spectra were acquired involving the first three ground vibrational levels corresponding to A3Π1 ← X1Σ+ transition. With the aid of spectral simulation, the BrI rotational lines were assigned. The nascent vibrational populations for v′′ = 0, 1, and 2 levels are obtained with a population ratio of 1:(0.58 ± 0.10):(0.34 ± 0.05), corresponding to a Boltzmann-like vibrational temperature of 713 ± 49 K. The quantum yield of the ground state BrI elimination reaction is determined to be 0.044 ± 0.014. The CCSD(T)//B3LYP/MIDI! method was employed to explore the potential energy surface for the unimolecular elimination of BrI from CH2BrI.

Herein, we have meticulously derived the nanosized fluorescent aggregates from pyrene Schiff base (PS) in DMSO:water (10:90) ratio. The aggregation property of PS molecule was characterized by SEM and TEM measurements, revealed the aggregated particles are in spherical shape with ~3 nm in size. Moreover, aggregates exhibit a high fluorescence quantum yield (48%) which was effectively used for the in vitro bioimaging of two different cancer cells such as A549 and MCF-7 cells in which it exhibiting excellent biocompatibility. Further, it was estimated the capability of twofold acridine orange/ethidium bromide (AO/EB) staining to identify the apoptotic associated changes in cancer cells. Additionally, the aggregates were successfully demonstrated as a luminescent probe for the perceptive biomolecule detection of bilirubin. On the other hand, the PS molecule was successfully utilized for protein binding and metal ion sensing studies. The interaction of bovine serum albumin (BSA) with PS molecule in DMSO was using fluorescence spectroscopic method and nature of interaction was also confirmed through molecular docking analysis. The PS molecule also acts as an excellent sensor for biologically important Fe3+ ion with detection limit of 336 nM. Overall, PS molecule can be a prospective material in biological field both in solution as well as aggregated forms. © 2019 Elsevier B.V.

Both single-laser and two-laser experiments were conducted to look into the ion-imaging of Br*(2P1/2) and Br(2P3/2) photofragmented from 1-bromo-2-methylbutane in the range 232-240 nm via a detection scheme of (2+1) resonance-enhanced multiphoton ionization. The angular analysis of these photofragment distributions yields the anisotropy parameter β = 1.88 ± 0.06 for the Br∗ excited state which arises from a parallel transition, while β = 0.63 ± 0.09 for the Br ground state indicates the contribution from both a perpendicular transition and a non-adiabatic transition. When a hexapole coupled with an orienting field was implemented, the parent molecules are spatially oriented to yield an orientation efficiency |«cos θ »| of 0.15. Besides the χ angle between the recoil velocity v and the transition dipole moment μ, orienting molecules allows for the evaluation of the angle α between v and the permanent molecular dipole moment d. The angular analysis of Br∗ photofragment distribution yields χ = 11.5° and α in the range from 160° to 180° with weak dependency. In the two-laser experiments, the angular anisotropy of Br photofragment distribution was found to be smaller (0.38 ± 0.10) when the photolysis wavelength was red-shifted to 240 nm, suggesting the increasing contributions from perpendicular transitions. © 2019 American Chemical Society.