Nickel Dioxide Research Articles

Comparisons of Cocoa Pod Husks and other Biomass Wastes for Syngas Production

In this study, the characteristics of sawdust, switch grass, cocoa pod husks, and bagasse were investigated and compared, as well as the effects of blended nickel and silicon dioxide catalysts on syngas production by gasification utilising a fluidised bed reactor. Because of their high volatile matter and cellulose content as well as low moisture content, sawdust, switch grass, cocoa pod husks, and bagasse were found to be appropriate for generating syngas. Experimental analysis was conducted on the sawdust, switch grass, cocoa pod husks and bagasse samples with and without catalyst. The grains in the samples were comparable in size, ranging from 2mm to 6mm. The catalysts were revealed to have a distinct influence on the gasification process. The efficiency of the processes improves with catalysts, while the generation of CO, CO2, HC, and NO decreases. Cocoa pod husks produced the highest HC value of 7928 ppm without catalysts while bagasse produced 1679 ppm that is the lowest HC value.

A novel quaternary carbon/metal oxide based nano‐composite electrode with high electrochemical capacitive performance

A facile one-pot hydrothermal method is employed to synthesize {CNT–MnO2–Ni(OH)2} (CMN), {rGO–MnO2–Ni(OH)2} (RMN) along with a novel composite material{rGO–CNT–MnO2–Ni(OH)2} (RCMN). This paper first time reports reduced graphene oxide–multiwall carbon nanotube–manganese dioxide–nickel hydroxide rGO–CNT–MnO2–Ni(OH)2 quaternary composite powder as a supercapacitor electrode material. The as-obtained rGO–CNT–MnO2–Ni(OH)2 quaternary composite shows high specific capacitance (1906.4 F g−1) at 3 mV s−1. In addition, cyclic stability measurement reveals that RCMN composite retains admirable capacitance (92.5%) even after 10,000 cycles. The enhancement in cyclic stability and specific capacitance is attributed to the exclusive combination of rGO/CNT as a conductive network and MnO2/Ni(OH) 2 nanostructures as active materials which endorse effective charge transfer and expedites high capacitance and cyclic stability.

Experimental study on mechanical properties of Ni/TiO2 FGM processed by pressureless sintering technique

In the present work, an experimental investigation and characterization of Functionally Graded Materials (FGMs) is carried out. The Nickel (Ni) and Titanium dioxide (TiO2) materials are taken as principal materials and the powder metallurgy technique is used for the preparation of specimens. The Nickel powder has a particle size of 20 μm with more than 99% purity and Titanium dioxide powder having 35 μm particle size with more than 99% purity is used for this study. The FGM specimens are prepared with five layers, with pure Nickel on one side and pure Titanium dioxide on opposite side of the specimen; and the three intermediate layers comprising of mixture of Nickel and Titanium dioxide. The five layered FGM samples are prepared with one inch diameter round die and the compacted samples are heated up to 1200°C in an inert gas (argon) atmosphere. The microscopic result shows that the microstructure of Ni/TiO2 FGM has varied layer-by-layer and the interface between the layers are observed. As a part of mechanical characterization, both green and sintered FGM sample densities are measured for each layer of the sample. The Rockwell hardness test method is used to find the hardness of the each layer in the samples. Linear shrinkage of the specimen is calculated with the help of green sample dimensions. The Compression test is conducted on the sintered specimens by using universal testing machine; stress-strain behaviour and maximum stress reported.

Design and tuning functionality of rod-like titanium dioxide–nickel oxide composites via a combinational methodology

TiO2–NiO composite nanorods were synthesized by combining hydrothermal growth of TiO2 nanorods and sputtering deposition of NiO film. Crystalline NiO coverage films with various thicknesses were sputter coated onto TiO2 nanorods by controlling NiO sputtering duration. The crystallographic analyses demonstrate that crystalline rutile TiO2-cubic NiO composite nanorods were formed herein. In comparison with pristine TiO2 and NiO, the coverage of NiO crystals on the TiO2 nanorods led to an enhanced photodegradation activity of the TiO2–NiO composites towards Rhodamine B dyes under irradiation. Moreover, the TiO2–NiO composite nanorods with the adequate content of NiO coverage layer show superior gas-sensing responses to 25–200 ppm ammonia gas in comparison with those of the constituent counterparts. The experimental results herein demonstrate that decoration of NiO film on the surfaces of TiO2 nanorods with tunable coverage sizes via sputtering deposition is a promising approach to design TiO2–NiO composite nanorods with desirable functionalities.

A Catalytic Asymmetric Ene Reaction for Direct Preparation of α-Hydroxy 1,4-Diketones as Intermediates in Natural Product Synthesis

Asymmetric access to α-hydroxy-1,4-diketones has been achieved by direct ene coupling of silyl enol ethers with glyoxal electrophiles, mediated by a chiral N,N′-dioxide–nickel(II) complex catalyst. Successful union of a polyketide silyl enol ether with an α-quaternary glyoxal, generated by dioxirane oxidation of an α-diazo ketone, models a proposed C5–C6 disconnection of the polyketide and spirocyclic imine domains of the marine natural product, portimine.

Catalytic asymmetric synthesis of 3,2'-pyrrolinyl spirooxindoles via conjugate addition/Schmidt-type rearrangement of vinyl azides and (E)-alkenyloxindoles.

A catalytic asymmetric conjugate addition/Schmidt-type rearrangement of vinyl azides and (E)-alkenyloxindoles was realized. It afforded a variety of optically active 3,2′-pyrrolinyl spirooxindoles with high yields (up to 98%), and excellent diastereo- and enantioselectivities (up to 98% ee, >19 : 1 dr), even at the gram-scale in the presence of a chiral N,N′-dioxide–nickel(ii) complex. In addition, a possible catalytic cycle and transition state model were proposed to rationalize the stereoselectivity.

Hierarchical Pt/MnO2–Ni(OH)2 Hybrid Nanoflakes with Enhanced Room-Temperature Formaldehyde Oxidation Activity

Nickel foam (NF)-supported Pt/MnNi@NF catalyst was prepared via in situ hydrothermal growth of manganese dioxide–nickel(II) hydroxide (MnO2–Ni(OH)2) hierarchical nanosheets and subsequent impregnat...

Gold(I)/Chiral N,N′‐Dioxide–Nickel(II) Relay Catalysis for Asymmetric Tandem Intermolecular Hydroalkoxylation/Claisen Rearrangement

AbstractA highly efficient asymmetric cascade reaction between alkynyl esters and allylic alcohols has been realized. Key to success was the combination of a hydroalkoxylation reaction catalyzed by a π‐acidic gold(I) complex with a Claisen rearrangement catalyzed by a chiral Lewis acidic N,N′‐dioxide–nickel(II) complex. A range of acyclic α‐allyl β‐keto esters were synthesized in high yields (up to 99 %) with good diastereoselectivities (up to 97:3) and excellent enantioselectivities (up to 99 % ee) under mild reaction conditions. These products can be easily transformed into optically active β‐hydroxy esters, β‐hydroxy acids, or 1,3‐diols.

ChemInform Abstract: Bimetallic Gold(I)/Chiral N,N′‐Dioxide Nickel(II) Asymmetric Relay Catalysis: Chemo‐ and Enantioselective Synthesis of Spiroketals and Spiroaminals.

A highly efficient asymmetric cascade reaction between keto esters and alkynyl alcohols and amides is reported. The success of the reaction was attributed to the combination of chiral Lewis acid N,N'-dioxide nickel(II) catalysis with achiral π-acid gold(I) catalysis working as an asymmetric relay catalytic system. The corresponding spiroketals and spiroaminals were synthesized in up to 99 % yield, 19:1 d.r., and more than 99 % ee under mild reaction conditions. Control experiments suggest that the N,N'-dioxide ligand was essential for the formation of the spiro products.

Bimetallic Gold(I)/Chiral N,N'-Dioxide Nickel(II) Asymmetric Relay Catalysis: Chemo- and Enantioselective Synthesis of Spiroketals and Spiroaminals.

A highly efficient asymmetric cascade reaction between keto esters and alkynyl alcohols and amides is reported. The success of the reaction was attributed to the combination of chiral Lewis acid N,N'-dioxide nickel(II) catalysis with achiral π-acid gold(I) catalysis working as an asymmetric relay catalytic system. The corresponding spiroketals and spiroaminals were synthesized in up to 99 % yield, 19:1 d.r., and more than 99 % ee under mild reaction conditions. Control experiments suggest that the N,N'-dioxide ligand was essential for the formation of the spiro products.

Bimetallic Gold(I)/Chiral N,N′‐Dioxide Nickel(II) Asymmetric Relay Catalysis: Chemo‐ and Enantioselective Synthesis of Spiroketals and Spiroaminals

AbstractA highly efficient asymmetric cascade reaction between keto esters and alkynyl alcohols and amides is reported. The success of the reaction was attributed to the combination of chiral Lewis acid N,N′‐dioxide nickel(II) catalysis with achiral π‐acid gold(I) catalysis working as an asymmetric relay catalytic system. The corresponding spiroketals and spiroaminals were synthesized in up to 99 % yield, 19:1 d.r., and more than 99 % ee under mild reaction conditions. Control experiments suggest that the N,N′‐dioxide ligand was essential for the formation of the spiro products.

Histopathological characteristics of Coregonus fishes under the impact of metal industry

This article provides results from monitoring studies of the state of common whitefish (Coregonus lavaretus L.) inhabiting the border Pasvik River and a number of lakes of Northern Fennoskandia. The water catchment area is subject to a significant contamination by coper, nickel, and sulfur dioxide due to the airborne transport of emissions from the Pechenganikel smelter. The ecological situation near the smelter is evaluated as very unfavorable and requires constant control, including the monitoring of aquatic systems. We used histopathologies of gills, liver, and kidneys as biomarkers to diagnose the state of sparsely rakered whitefish. Changes in their cellular structure were diagnosed and classified. The presence of the revealed abnormalities is associated with long-term aerotechnogenic stress on the investigated water bodies. The possibility of using the obtained data for assessing water quality has been considered.

Systematic Expansion of Active Spaces beyond the CASSCF Limit: A GASSCF/SplitGAS Benchmark Study.

The applicability and accuracy of the generalized active space self-consistent field, (GASSCF), and (SplitGAS) methods are presented. The GASSCF method enables the exploration of larger active spaces than with the conventional complete active space SCF, (CASSCF), by fragmentation of a large space into subspaces and by controlling the interspace excitations. In the SplitGAS method, the GAS configuration interaction, CI, expansion is further partitioned in two parts: the principal, which includes the most important configuration state functions, and an extended, containing less relevant but not negligible ones. An effective Hamiltonian is then generated, with the extended part acting as a perturbation to the principal space. Excitation energies of ozone, furan, pyrrole, nickel dioxide, and copper tetrachloride dianion are reported. Various partitioning schemes of the GASSCF and SplitGAS CI expansions are considered and compared with the complete active space followed by second-order perturbation theory, (CASPT2), and multireference CI method, (MRCI), or available experimental data. General guidelines for the optimum applicability of these methods are discussed together with their current limitations.

Preparation of Nickel and Manganese Dioxide by Co-Precipitation and its Electrochemical Capacitive Properties

The precursor nickel and manganese carbonates were synthesized by co-precipitation with sodium carbonate as precipitant, and then nickel and manganese oxides were gained after calcination. The phase and morphology of the synthesized product were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the electrochemical characterization was performed using cyclic voltammetry (CV), galvanostatic charge–discharge tests (GCD) and electrochemical impedance spectroscopy (EIS) in a 6mol/L KOH aqueous solution electrolyte. The result showed that the products were the mixture of nickel and manganese oxides and solid solution. nanoparticles and spherical particles were gained by controlling the molar ratio of nickel and manganese. All of the samples exhibited typical Faradic redox capacitance. The specific capacitance was different with the change of nickel and manganese molar ratio. The specific capacitance (Cs) reached 130F/g at 1A/g when the ratio was 2:1.

Asymmetric Synthesis of Spirocyclic Oxindole‐Fused Tetrahydrothiophenes via N,N′‐Dioxide–Nickel(II) Catalyzed Domino Reaction of 1,4‐Dithiane‐2,5‐diol with 3‐Alkenyloxindoles

AbstractA highly efficient chiral N,N′‐dioxide–nickel(II) complex system has been developed to catalyze the domino thia‐Michael/aldol reaction of 1,4‐dithiane‐2,5‐diol with 3‐alkenyloxindoles. A series of the desired spirocyclic oxindole‐fused tetrahydrothiophenes was obtained in good yields with excellent ee and dr (up to 97% yield, 98% ee, >19:1 dr). Besides, based on the X‐ray crystal structure of the catalyst as well as the absolute configuration of the product, a catalytic model was proposed to explain the stereocontrol process.magnified image

Asymmetric synthesis of spiro[isoxazolin-3,3'-oxindoles] via the catalytic 1,3-dipolar cycloaddition reaction of nitrile oxides.

A highly enantioselective 1,3-dipolar cycloaddition of nitrile oxides with 3-arylidene-oxindoles was realized by a chiral N,N'-dioxide-nickel(II) complex catalyst under mild reaction conditions. A series of spiro-isoxazoline-oxindole derivatives were obtained in moderate yields (up to 65%) with good regioselectivities (up to 99:1), excellent enantioselectivities (up to 99% ee), and exclusive diastereoselectivity as well.

Titanium dioxide–nickel oxide composite coatings: Preparation by mechanical coating/thermal oxidation and photocatalytic activity

Photocatalytic TiO2–NiO composite coatings were prepared by the mechanical coating technique and subsequent heat oxidation. The preparation process is examined in detail. The prepared coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The results showed that Ni particles were mainly located at the inner layer of these composite coatings if prepared by 1-step MCT, whereas the Ni particles adhered to the surfaces of the Ti–Ni composite coatings if prepared by 2-step MCT. At oxidation temperatures of 973 and 1073K, the Ti coatings were partly oxidized to rutile TiO2 and a Ti–TiO2–NiO composite microstructure was formed. When the oxidation temperature was further increased to 1173 and 1273K, the Ti coatings were oxidized to rutile TiO2 and a TiO2–NiO composite microstructure was obtained. The photocatalytic activity of these composite coatings was evaluated by the degradation of a methylene-blue (MB) solution under UV irradiation. The results showed that the sample prepared by 2-step MCT and subsequent heat oxidation at 1073K had the highest photocatalytic activity, i.e., more than 200nmolL−1h−1. The improvement in the photocatalytic activity could be attributed to the efficiency increase in charge separation, which may result from the formation of the TiO2–Ti composite microstructure and TiO2–NiO p–n heterojunctions.

N,N′-Dioxide–nickel(II) complex catalyzed asymmetric Michael addition of cyclic 1,3-dicarbonyl compounds to β,γ-unsaturated α-ketoesters

A direct asymmetric Michael addition of cyclic 1,3-dicarbonyl compounds to β,γ-unsaturated α-ketoesters could be efficiently catalyzed by an N, N′-dioxide–nickel(II) complex. A series of chiral warfarin derivatives were obtained in excellent yields (up to 99%) with high enantioselectivities (up to 90% ee) under mild conditions within shorter reaction time.

Enantioselective Recognition of α-Hydroxycarboxylic Acids and N-Boc-Amino Acids by Counterion-Displacement Assays with a Chiral Nickel(II) Complex

A new chiral sensor based on an N,N'-dioxide nickel(II) complex was prepared, which could visually recognize a series of chiral α-hydroxycarboxylic acid enantiomers by coordination and self-assembly forming into nanospheres or nanofibers. With the help of various techniques, the morphology structures of the colloid or suspension were obtained and the counterion-displacement assays were also confirmed. In addition, this metal complex could act as a highly enantioselective fluorescence sensor to recognize N-Boc-amino acids and chiral α-hydroxycarboxylic acids.

ChemInform Abstract: Efficient Synthesis of β‐Hydroxy‐α‐amino Acid Derivatives via Direct Catalytic Asymmetric Aldol Reaction of α‐Isothiocyanato Imide with Aldehydes.

AbstractA chiral N,N′‐dioxide—nickel(II) complex is applied in the asymmetric direct aldol reaction of α‐isothiocyanato imide (I) with aromatic, α,‐unsaturated, heteroaromatic, and aliphatic aldehydes are converted into the desired adducts with high enantioselectivities under mild conditions.