Search

The development of high-efficiency and durable bifunctional electrocatalysts is an important and challenging topic in the area of energy storage/conversion. Herein, we prepared metallic cobalt nanoparticle decorated N-doped graphitic sheets (Co@NGr) by adopting facile pyrolysis of a mixed ligand cobalt-based MOF (CoMOF-2) as a sacrificial template displaying good OER and HER activity. The catalytic material harvested at three different pyrolytic temperatures was characterized by various analytical methods such as PXRD, SEM, TEM, Raman, and XPS analyses. The catalytic activity of the obtained hybrid composite materials towards oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) was studied. Co@NGr-900 was found to be an efficient bifunctional electrocatalyst and 10 mA cm−2 current density was afforded at an overpotential of 390 mV for OER and 340 mV for HER respectively. This study provides insight for the development of cost-effective nonprecious element-based electrocatalysts for water splitting which has relevance in energy storage and conversion. Catalytic performance is governed by the synergistic compositional effect of metallic cobalt/nitrogen-doping in the graphitic carbon increasing the electrical conductivity/active sites of the composite material.

The major objective of the present investigation to study the effect of Zn/Zr dopant on M type-barium hexagonal ferrites on structure and properties. During present work, we have synthesized a series of BaZnxZrxFe(12-₂x)O19 ferrites (x=0, 0.1, 0.3, 0.5, 0.7, and 0.9) using sol-gel auto combustion method using citric acid as fuel and precursor was calcined at 900°C for 6 hour. These compounds were characterized by FTIR, XRD, VSM, TEM. XRD data of Barium hexaferrite (BAM) material reveals pure phase and have no traces of intermediate phase such as α/γ –Fe2O3 and BaCO3. The BaM series crystal size ranging from 38.9 to 66.9 nm and average size of particle is 49.7 nm. FTIR analysis give information about the functional groups and molecular bands present in the calcined barium hexaferrite material. Magnetic measurements reveal that the values of coercivity ranges viz Hc 4875Oe (x = 0) to 835Oe (x=0.9). The saturation magnetization (Ms) values are in the range of 58.2 to 33.4 emu/g.

High permeance membranes selective towards small ions and solutes are required to produce high-quality product water. Conventional semi-aromatic polyamide thin-film composite (TFC) nanofiltration membranes prepared via interfacial polymerization of diamine, e.g., piperazine (PIP) and acid chloride, do not show the precise separation of small solutes (

Synthesis of BaZn0.6Zr0.6Fe10.8O19 powder samples using sol–gel-auto-combustion method has been reported. The impact of calcination temperature on the structural, magnetic and surface morphology of these samples has been investigated. XRD data confirms that the samples are phase pure and have no traces of intermediate phase such as α/γ-Fe2O3 and BaCO3 etc. The lattice parameters and cell volume increase slightly with increase in calcination temperature. The c/a parameter is

The properties of the heterojunction devices are predetermined based on the bandgap and the extent of dopping of their constituent semiconductors and are not tunable in-situ . Albeit in this manuscript a new concept of in-situ tuning of heterojunction has been introduced. pP heterojunction using conducting polymers, polyaniline (PANI) and poly (3,4-ethylenedioxythiophene) (PEDOT) has been fabricated. The junction was studied by scanning electron microscopy and atomic force microscopy. The rectification behavior was studied through current density (J)–voltage (V) characteristics at various electrochemical potentials by superimposing small voltage steps (bias voltage) over a steady electrochemical potential using bipotentiostat. The rectification was found tunable as a function of electrochemical state of the polymers in in-situ conditions.

The effect of co-doping of Zn2+/Zr4+ ions on surface morphology, structure and magnetic properties of BaZnxZrxFe12-2xO19 (x=0.00, 0.20,0.40,0.60,0.80, 1.00) synthesized using Pechini method has been investigated. XRD data reveals that the samples are phase pure and have no intermittent phase. The c/a parameter is 2+/Zr4+ dopant seen using FE-SEM micrographs. The local crystal structure distortion with increasing Zn2+/Zr4+ dopant composition is confirm by Raman measurements. M vs H plots reveal that all the samples shows magnetic ordering. The highest Ms value has been noticed to be 68.43 emu/g in x=0.20 sample. The Hc value varies from 5350 Oe to 763 Oe with increase in dopant concentration. These materials have strong potential in magnetic recording applications.

An electrochemical method for loading electroactive materials over the TEM grid is reported. The protocol has been demonstrated using polyaniline as an example. The electroactive polymer was directly deposited over the Au TEM grid, used as working electrode in a 3 electrode electrochemical cell. The undisturbed as-deposited morphologies under the influence of various counter ions and ex situ electrochemical states have been studied and compared. Contrary to behaviour in bulk the individual polyaniline fibre was found thinner at anodic potentials. The movement of counter ions as a function of the electrochemical state of the polymer was studied using STEM-EDX elemental mapping.

Two dual ligand isostructural coordination polymers [Co(BrIP)(BIX)]n (1) and [Zn(BrIP)(BIX)]n (2), where BrIP = 5-bromoisophthalate and BIX = 1,4-bis(imidazol-1-ylmethyl)-benzene, have been efficiently synthesized by liquid assisted grinding methods. Single crystals of 1 were harvested by the solvothermal technique and phase pure 1 or 2 can be quantitatively obtained by grinding equimolar amounts of the metal nitrates and the ligands, 5-bromoisophthalic acid (H2BrIP) and 1,4-bis(imidazol-1-ylmethyl)-benzene (BIX) in the presence of a few drops of water or methanol. Use of freshly prepared Co(OH)2 or ZnO also yields the desired end products in an environmentally friendly manner along with the benign by-product water. The structure of 1 was established by single crystal X-ray diffraction studies, in addition to other physicochemical techniques. Morphological aspects of samples of 1 and 2 obtained via different protocols have also been studied.

The structure-property correlation in the Cu-TCNQ organometallic complex is very important for explaining its unusual electrical, optical and magnetic properties. Consequently several morphological studies and their correlation with the properties of these materials can be found in the literature, although no systematic study of various morphologies with growth conditions and their correlation has been reported to the best of our knowledge. Therefore in this manuscript the interconversion of various morphologies is reported using electron and probe microscopies. A conventional Cu TEM grid acted as the copper source to form a Cu-TCNQ complex and the complex, which formed at the surface of the TEM grid. The complex thus prepared was characterized by FTIR and Raman spectroscopic techniques. The shifting of -C N from 2221 cm−1 (TCNQ) to 2201 cm−1 indicates formation of a complex and the identical nature of IR spectra in two phases indicates that they are polymorphs. The morphologies of Cu-TCNQ were followed through FE-SEM and TEM studies. Various morphologies such as needle, square tube, platelet etc. were observed as a function of time. A distinct transition from needle to platelet morphology was observed as the complex grew. The conductance of various morphologies in phase-I as well as phase-II were also measured and compared by Spreading Resistance Imaging (SRI) at different bias voltage i.e. 1 V, 3 V and 5 V.

Sustainable intensification of agricultural productivity is a global challenge. The sap of the commercially important red seaweed, Kappaphycus alvarezii, has been of interest in this regard, and its application as foliar spray has had a profound impact on the yields of many crops. It has been shown to contain indole acetic acid, kinetin, zeatin and gibberellic acid (GA3) but no study is yet reported on the interactions among these constituents, if any. In the present study, selective solvent extraction was undertaken to obtain GA3-free and indole acetic acid-free sap compositions. Another composition was prepared by autoclaving the sap which resulted in degradation of all the above growth hormones. The sap variants, along with water spray (control) and pristine sap, were applied on Zea mays as foliar spray over three consecutive seasons in dilute form. The four sap treatments were at par with one another—and significantly superior to control treatment—in so far as grain yield and quality were concerned. Pristine sap was subsequently shown to also contain choline and glycine betaine, and these were detected in similar amounts in all the sap variants, apparently indicating their profound influence on grain yield. Another important observation was that GA3-free sap led to heightened photosynthetic activity which translated into 26 % increase in corn stover yield compared to pristine sap. This is hypothesized to be on account of prevention of negative interactions between GA3 and other hormones. The study constitutes the first report of enhancement of performance of a natural seaweed plant stimulant towards increasing plant growth through simplification of its composition.

This work evaluates cationic intercalation of Capecitabine (Xeloda), an antineoplastic agent in interlayer gallery of Na + -MMT, which was further compounded with Poly ( L -Lactide) to form microcomposite spheres, for oral chemotherapy of breast cancer. The XRD, TGA, SEM, TEM and FT-IR analysis indicated the CAP intercalated in interlayer of MMT and stabilized in the longitudinal monolayer mode by electrostatic interface. No significant alteration in fundamental active properties of CAP was found in the MMT efficacy and data from in vitro study showed controlled drug release pattern >72 h. The efficacy of CAP-MMT hybrid/MPs was also confirmed on Human neuroblastoma cell line (IMR32) by in vitro cell culture experiments evaluating cell cytotoxic and oxidative stress marker indices which showed that intercalated drug and MPs, were as effective as pristine drug. In vivo pharmacokinetics of CAP-MMT hybrids in rats was examined and plasma CAP levels were evaluated. Our findings suggest that CAP-MMT hybrids and MPs can be of considerable value in chemotherapy of malignant neoplastic disease with reduced side effects and clearly demonstrated that MMT not only plays a role as a delivery matrix for drug but also facilitates significant increase in the delivery proficiency.

The controlled formation of porous ZnO microtubes via the formation of tubular hydrozincite under ambient conditions from bulk ZnO followed by calcination at 500 °C for 2 h is presented. The tubular structure is a hierarchical assembly of ZnO flowers to form uniform tubes, with ∼30 μm length, ∼2 to 7 μm width and ∼400 to 500 nm wall thickness, where the flowers are made of 3D assembled porous ZnO flakes. The surface area of the tubular ZnO structure is quite good (58 m2 g−1). The developed synthetic procedure is quite flexible, and we have also synthesized nanostructured ZnO of varying morphologies from bulk ZnO just by changing the synthetic conditions. The developed ZnO microtubes showed excellent microstructure-based sensing and catalytic properties. A novel biosensor based on the synthesized porous tubular ZnO exhibited high sensitivity (54.5 mA M−1 cm−2) and low LOD (limit of detection, 0.2 mM (S/N = 3)) of cholesterol at room temperature, superior to that of sensors made of other porous ZnO shapes synthesized by varying the conditions, as well as other sensors reported in the literature. It is superior even in comparison with a nano gold modified sensor. The tubular ZnO structure also showed superior catalytic activity (92%) for the synthesis of 5-benzyl-1H-tetrazole to that of other reported solid catalysts. Thus, it is expected that the developed porous tubular ZnO should find potential industrial application in the sensor as well as the catalysis field. Moreover, the synthesis from bulk ZnO makes the procedure cost effective.

Preparation of a high flux poly(dimethylsiloxane) (PDMS) membrane for separation of organics from water by pervaporation has been a challenging task. For this, the membrane should be as thin as possible since the productivity flux is inversely proportional to the membrane thickness. In an attempt to understand the relationship between the membrane structure and flux, the membranes of different thickness varying from about 0.2 to 150 μm were prepared and studied. The neat PDMS membrane prepared by evaporation casting of the 10% (w/w) polymer solution in n-hexane has an average thickness of 150 μm while a porous support was used for preparing the thinner membranes. ATR-IR, SEM, DSC, XRD and Contact angle measurements showed that the thinner membrane had relatively more crystalline domains and less hydrophobic. The nanostructure of the membranes was investigated using small angle neutron scattering (SANS) measurements. While the SANS data of the neat membrane was fitted well with Debye model of polymer chain, the data of coated membranes was fitted with a combination of Debye chain model and some aggregated structure of polymer chains. Among the coated PDMS films, the thinly coated film exhibited relatively a higher amount of the chain aggregates. This might imply that the thinner membrane had a relatively loose structure responsible for low selectivity but high flux in the separation of organic from water by pervaporation.

The composite membranes capable of recognizing enantiomers of lysine monohydrochloride were prepared by interfacial polymerization of l -lysine and piperazine with trimesoyl chloride in situ on the surface of polysulfone membrane. The chemistry and thickness of selective layer determined by variable angle ATR–FTIR spectroscopy and the morphology of membranes examined by scanning electron microscope to understand and correlate with performance of membrane. Pure enantiomers were separated from aqueous solution of racemic lysine monohydrochloride at low pressures in membrane testing module to determine the performance of membranes for optical resolution. The effect of composition of solutions used to prepare chiral selective layer on the performance of membranes was determined. The effects of separation process parameters such as trans-membrane pressure, permeation time and concentration of feed solution on flux and separation were also determined. The membranes indicated preferential permeability for d -lysine monohydrochloride by enriching permeates up to 90% enantiomeric excess. The membrane prepared using l -lysine and piperazine monomers in equal proportion (W/W) exhibited highest enantiomeric excess (90%). The trans-membrane pressure and concentration of feed solution indicated remarkable effect on enantioselective permeability of membranes. Highest enantiomeric excess and flux obtained with dilute feed solution at 172 kPa.

Pervaporation membrane technology is commercially successful in the dehydration of organic solvents, and the technology has potential for seawater desalination with high recovery because of its capability to treat highly saline water. But to make the technology advantageous over the other available membrane desalination technologies in terms of productivity flux without additional energy cost, the selective barrier layer is required to be extremely thin, defect-free, hydrophilic, and selective to water. In this work, we prepared an efficient membrane by reinforcing a highly water-permeable but continuous barrier layer of poly(vinyl alcohol)–silica (PVA-SiO2) hybrid material on porous polysulfone hollow fibers. The PVA-SiO2 in acidified and hydrated ethanol was aged at room temperature for a period to allow solvent evaporation to obtain the solution concentration desired for the reinforcement. The reinforced hollow fiber membrane with optimal PVA-SiO2 barrier layer thickness exhibited a performance with a flux of 20.6 L m−2 h−1 and 99.9% salt rejection from a saline feed of 2000 ppm NaCl at 333 K. The effects of PVA-SiO2, temperature, and feed salinity on the pervaporation performance of the membrane were also studied. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45718