Catalyst-Packed Non-Thermal Plasma Reactor for Removal of Nitrogen Oxides

A single-stage plasma-catalytic reactor in which catalytic materials were packed was used to remove nitrogen oxides. The packing material was scoria being made of various metal oxides including Al2O3, MgO, TiO2, etc. Scoria was able to act not only as dielectric pellets but also as a catalyst in the presence of reducing agent such as ethylene and ammonia. Without plasma discharge, scoria did not work well as a catalyst in the temperature range of 100 °C to 200 °C, showing less than 10% of NOx removal efficiency. When plasma is produced inside the reactor, the NOx removal efficiency could be increased to 60% in this temperature range.

Metal cholate hydrogels: versatile supramolecular systems for nanoparticle embedded soft hybrid materials

This work describes the formation of hydrogels from sodium cholate solution in the presence of a variety of metal ions (Ca2+, Cu2+, Co2+, Zn2+, Cd2+, Hg2+ and Ag+). Morphological studies of the xerogels by electron microscopy reveal the presence of helical nanofibres. The rigid helical framework in the calcium cholate hydrogel was utilised to synthesize hybrid materials (AuNPs and AgNPs). Doping of transition metal salts into the calcium cholate hydrogel brings out the possibility of synthesising metal sulphide nano-architectures keeping the hydrogel network intact. These novel gel-nanoparticle hybrid materials have encouraging application potentials.

The effect of minor addition of Ni on the microstructural evolution and mechanical properties of suction cast Al-0.14 at. pct Sc binary alloy

Aluminum scandium binary alloys represent a promising precipitation-hardening alloy system. However, the hardness of the binary alloys decreases with the rapid coarsening of Al3Sc precipitate during high-temperature aging. In the current study, we report a new approach to compensate for the loss of mechanical properties by combining rapid solidification with very small ternary addition of transition metal Ni. This addition yields dispersion, and at a critical concentration improves the mechanical properties. We explore additions of a maximum of 0.06 at. pct of Nickel to a binary Al-0.14 at. pct Sc alloy, which yield nickel-rich dispersions. We report two kinds of biphasic dispersions containing AlNi2Sc/Al9Ni2 and alpha-Al/Al9Ni2 phase combinations. The maximum improvement in mechanical properties occurs with the addition of 0.045 at. pct Ni with a yield strength of 239 +/- A 7 MPa for an aging treatment at 583 K (310 A degrees C) for 15 hours. DOI: 10.1007/s11661-013-1624-z (C) The Minerals, Metals & Materials Society and ASM International 2013

Direct conversion of calcium carbonate to C-1-C-3 hydrocarbons

With the objective of investigating the direct conversion of inorganic carbonates such as CaCO3 to hydrocarbons, assisted by transition metal ions, we have carried out studies on CaCO3 in an intimate admixture with iron oxides (FeCaCO) with a wide range of Fe/Ca mole ratios (x), prepared by co-precipitation. The hydrogen reduction of FeCaCO at 673 K gives up to 23% yield of the hydrocarbons CH4, C2H4, C2H6 and C3H8, leaving solid iron residues in the form of iron metal, oxides and carbide particles. The yield of hydrocarbons increases with x and the conversion of hydrocarbons occurs through the formation of CO. While the total yield of hydrocarbons obtained by us is comparable to that in the Fischer-Tropsch synthesis, the selectivity for C-2-C-3 hydrocarbons reported here is noteworthy.

Enhancing hydrogen storage capacity of pyridine-based metal organic framework

Using first principles calculations, we show that the storage capacity as well as desorption temperature of MOFs can be significantly enhanced by decorating pyridine (a common linker in MOFs) by metal atoms. The storage capacity of metal-pyridine complexes are found to be dependent on the type of decorating metal atom. Among the 3d transition metal atoms, Sc turns out to be the most efficient storing unto four H-2 molecules. Most importantly, Sc does not suffer dimerisation on the surface of pyridine, keeping the storage capacity of every metal atom intact. Based on these findings, we propose a metal-decorated pyridine-based MOFs, which has potential to meet the required H-2 storage capacity for vehicular usage. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Regioselective Thiolation of Arenes and Heteroarenes: C-H Functionalization Strategy for C-S Bond Formation

A facile transition-metal-free oxidative cross-dehydrogenative coupling reaction involving selective formation of a C-S bond leading to the synthesis of arylthiobenzoxazoles, heteroarylthiobenzoxazoles, and arylthiobenzothiazoles has been described. This highly regioselective C-H functionalization reaction with electron-rich aromatic systems including heteroaromatics is achieved by reversing the reactivity of sulfur in the presence of a suitable oxidant and strong acid.

Pt-Poisoning-Free Efficient CO Oxidation on Pt3Co Supported on MgO(100): An Ab Initio Study

Late-transition-metal-doped Pt clusters are prevalent in CO oxidation catalysis, as they exhibit better catalytic activity than pure Pt, while reducing the effective cost and poisoning However, completely eliminating the critical problem of Pt poisoning still poses a big challenge. Here, we report for the first time that, among the bimetallic clusters ((Pt3M where M = Co, Ni, and Cu)/MgO(100)), the CO adsorption site inverts for Pt3Co/MgO(100) from Pt to Co, due to the complete uptake of Pt d-states by lattice oxygen. While this resolves the problem of Pt poisoning, good reaction kinetics are predicted through low barriers for Langmuir-Hinshelwood and Mars van Krevelen (MvK) mechanisms of CO oxidation for Pt3Co/MgO(100) and Li-doped MgO(100), respectively. Li doping in MgO(100) compensates for the charge imbalance caused by a spontaneous oxygen vacancy formation. Pt-3 Co/Li-doped MgO(100) stands out as an exceptional CO oxidation catalyst, giving an MvK reaction barrier as low as 0.11 eV. We thereby propose a novel design strategy of d-band center inversion for CO oxidation catalysts with no Pt poisoning and excellent reaction kinetics.

Synthesis, and crystal and electronic structure of sodium metal phosphate for use as a hybrid capacitor in non-aqueous electrolyte

Energy storage devices based on sodium have been considered as an alternative to traditional lithium based systems because of the natural abundance, cost effectiveness and low environmental impact of sodium. Their synthesis, and crystal and electronic properties have been discussed, because of the importance of electronic conductivity in supercapacitors for high rate applications. The density of states of a mixed sodium transition metal phosphate (maricite, NaMn1/3Co1/3Ni1/3PO4) has been determined with the ab initio generalized gradient approximation (GGA)+Hubbard term (U) method. The computed results for the mixed maricite are compared with the band gap of the parent NaFePO4 and the electrochemical experimental results are in good agreement. A mixed sodium transition metal phosphate served as an active electrode material for a hybrid supercapacitor. The hybrid device (maricite versus carbon) in a nonaqueous electrolyte shows redox peaks in the cyclic voltammograms and asymmetric profiles in the charge-discharge curves while exhibiting a specific capacitance of 40 F g(-1) and these processes are found to be quasi-reversible. After long term cycling, the device exhibits excellent capacity retention (95%) and coulombic efficiency (92%). The presence of carbon and the nanocomposite morphology, identified through X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) studies, ensures the high rate capability while offering possibilities to develop new cathode materials for sodium hybrid devices.

Organic-inorganic hybrid PtCo nanoparticle with high electrocatalytic activity and durability for oxygen reduction

In Pt-transition metal (TM) alloy catalysts, the electron transfer from the TM to Pt is retarded owing to the inevitable oxidation of the TM surface by oxygen. In addition, acidic electrolytes such as those employed in fuel cells accelerate the dissolution of the surface TM oxide, which leads to catalyst degradation. Herein, we propose a novel synthesis strategy that selectively modifies the electronic structure of surface Co atoms with N-containing polymers, resulting in highly active and durable PtCo nanoparticle catalysts useful for the oxygen reduction reaction (ORR). The polymer, which is functionalized on carbon black, selectively interacts with the Co precursor, resulting in Co-N bond formation on the PtCo nanoparticle surface. Electron transfer from Co to Pt in the PtCo nanoparticles modified by the polymer is enhanced by the increase in the difference in electronegativity between Pt and Co compared with that in bare PtCo nanoparticles with the TM surface oxides. In addition, the dissolution of Co and Pt is prevented by the selective passivation of surface Co atoms and the decrease in the O-binding energy of surface Pt atoms. As a result, the catalytic activity and durability of PtCo nanoparticles for the ORR are significantly improved by the electronic ensemble effects. The proposed organic/inorganic hybrid concept will provide new insights into the tuning of nanomaterials consisting of heterogeneous metallic elements for various electrochemical and chemical applications.

Density functional theory based study of chlorine doped WS2-metal interface

Investigation of a transition metal dichalcogenide (TMD)-metal interface is essential for the effective functioning of monolayer TMD based field effect transistors. In this work, we employ the Density Functional Theory calculations to analyze the modulation of the electronic structure of monolayer WS2 with chlorine doping and the relative changes in the contact properties when interfaced with gold and palladium. We initially examine the atomic and electronic structures of pure and doped monolayer WS2 supercell and explore the formation of midgap states with band splitting near the conduction band edge. Further, we analyze the contact nature of the pure supercell with Au and Pd. We find that while Au is physiosorbed and forms n-type contact, Pd is chemisorped and forms p-type contact with a higher valence electron density. Next, we study the interface formed between the Cl-doped supercell and metals and observe a reduction in the Schottky barrier height (SBH) in comparison to the pure supercell. This reduction found is higher for Pd in comparison to Au, which is further validated by examining the charge transfer occurring at the interface. Our study confirms that Cl doping is an efficient mechanism to reduce the n-SBH for both Au and Pd, which form different types of contact with WS2. (C) 2016 AIP Publishing LLC.

Nanocrystalline Janus films of inorganic materials prepared at the liquid-liquid interface

The interface between toluene and water has been employed to prepare ultrathin Janus nanocrystalline films of metal oxides, metal chalcogenides and gold, wherein the surface on the organic-side is hydrophobic and the aqueous-side is hydrophilic. We have changed the nature of the metal precursor or capping agent in the organic layer to increase the hydrophobicity. The strategy employed for this purpose is to increase the length of the alkane chain in the precursor or use a perfluroalkane derivative as precursor or as a capping agent. The hydrophobicity and hydrophilicity of the Janus films have been determined by contact angle measurements. The morphology of hydrophobic and hydrophilic sides of the film have been examined by field emission scanning electron microscopy.

Synthesis and structure of mixed ligand isonitroso-β-ketoiminenickel(II) complexes. Crystal structure of (1-ethoxycarbonyl-2-npropylimino-1-propanoneoximato) (1-methoxycarbonyl-2-imino-1-propanoneoximato)nickel(II)

Mixed ligand complexes of the type Ni(R-AB)(AC') and Ni(R-AC)(AB') where AB/AC denote N-bonded isonitroso- [3-ketoimino ligands, AB'/AC' denote the corresponding Obonded ligands and R = Me, Et, n-Pr are synthesised and characterised. The complexes are neutral with square planar geometry around nickel(II). The bonding isomerism of the isonitroso group is discussed on the basis of i.r. and 1H n.m.r. studies. The crystal structure of the title complex, Ni(n-Pr-IEAI)(IMAI') has been determined from diffractometer data by Patterson and Fourier methods and refined by least squares to R = 0.088 for 2209 observed reflections. Unit cell constants are: a = 11.945(2), b = 22.436(7), c = 13.248(5) ~, [3 = 95.13(2) ~ The space group is P2Jc with Z = 8. Niekel(II) has a square planar coordination of two imine nitrogens, an isonitroso-nitrogen (from n-Pr-IEAI) and another isonitrosooxygen (from IMAI').

Vacancy ordered phases and one-dimensional quasiperiodicity

The metastable vacancy ordered phases observed in aluminium transition metal alloys on rapid solidification or vapour deposition can be considered as a periodic arrangement of a truncated quasiperiodic string based on the Fibonacci sequence along the left angle bracket111right-pointing angle bracket stacking direction of the original CsCl cell. Using the projection formalism developed in the context of quasicrystals, the diffraction patterns of the vacancy ordered phases are calculated for both commensurate and incommensurate projection from a periodic cubic cell in four dimensions. These are compared with experimentally observed patterns. It is shown that at increasingly longer periodicity the patterns from commensurate crystals become indistinguishable from the truly quasiperiodic one. It is suggested that there is a strong link between vacancy ordered phases and quasicrystals.

Studies on the reactions of thionyl fluoride

Thionyl fluoride undergoes quantitative oxidation with chloramine-T and reduction with lithium aluminium hydride and sodium borohydride. At elevated temperatures, (>150°C) it reacts with metals such as copper, silver, zinc and lead forming the corresponding metal sulphides, fluorides and sulphur dioxide. With the respective metal oxides, the metal fluorides and sulphur dioxide are formed.

Complexes of lanthanide perchlorates with two new O,N,O ligands derived from antipyraldehyde and acetic and benzoic acid hydrazides

Antipyrine is a well known ligand for lanthanides (I). A forage through the organic literature of pyrazolones reveals that the 4-position of antipyrine is amenable to a wide variety of organic reactions. It should thus be possible to introduce suitable functional groups at this position and design new multidentate ligands for metal ions. It is also found that the coordination chemistry of lanthanides is much less well developed and far fewer ligands have been used for complexation with lanthanide ions compared to that of the d-transition metal ions. Keeping these points in view we have reported earlier, complexes of lanthanides with a bidentate ligand N,N-diethyl-antipyrine-4-carboxamide (2). In this communication we report the synthesis of two new ligands from Schiff base condensation of antipyraldehyde and the hydrazides of acetic and benzoic acids and the complexes formed by these hydrazones with lanthanide perchlorates.