A mild aqueous synthesis of ligand-free copper nanoparticles for low temperature sintering nanopastes with nickel salt assistance

An organic ligand-free aqueous-phase synthesis of copper (Cu) nanoparticles (NPs) under an air atmosphere was successfully achieved by reducing copper(II) oxide particles with a leaf-like shape in the presence of Ni salts at room temperature. The resulting Cu NPs with a mean particle diameter of ca. 150 nm exhibited low-temperature sintering properties due to their polycrystalline internal structure and ligand-free surface. These Cu NPs were applied to obtain Cu NP-based nanopastes with low-temperature sintering properties, and the resistivities of the obtained Cu electrodes after annealing at 150 °C and 200 °C for 30 min were 64 μΩ∙cm and 27 μΩ∙cm, respectively. The bonding strength between oxygen-free Cu plates prepared using the Cu NP-based nanopastes reached 32 MPa after pressure-less sintering at 260 °C for 30 min under a nitrogen atmosphere. The developed manufacturing processes using the developed Cu nanopastes could provide sustainable and low-CO2-emission approaches to obtain Cu electrodes on flexible films and high-strength bonding between metal plates as die-attach materials for power devices under energy- and resource-saving conditions.

Design of ZIF-67 MOF-derived Co3O4/NiCo2O4 nanosheets for supercapacitor electrode materials

Binary transition metal oxides exhibit improved properties including good redox potentials and electrical conductivities compared with single metal oxides as electrode materials in energy storage. Herein, ZIF-67 is prepared by a one-step method using Co2+ as the central metal ion, 2-methylimidazole as the organic ligand, and methanol as an organic solvent at room temperature. Hollow NiCo2O4 and sheet-like Co3O4/NiCo2O4 derived from bimetallic imidazolate framework precursors were synthesized by adding cobalt and nickel ions in appropriate proportions. A hollow and porous structure is achieved for the reaction between a nickel salt and ZIF-67, and this unique nanostructure provides a high active surface area, which is beneficial to the electrochemical properties. Several samples are prepared and used as electrode materials for electrochemical tests in 6 M KOH. As a result, the Co3O4/NiCo2O4 electrode with a sheet nanostructure showed a high specific capacitance of 846 F g−1 at a current density of 0.5 A g−1. This Co3O4/NiCo2O4 electrode material is promising for future studies on high-performance supercapacitors to solve emerging energy-related problems. [Formula: see text]

Nickel Boride Catalyzed Reductions of Nitro Compounds and Azides: Nanocellulose-supported Catalysts in Tandem Reactions

Nickel boride catalyst prepared in situ from NiCl2 and sodium borohydride allowed, in the presence of an aqueous solution of TEMPO-oxidized nanocellulose (0.01 wt%), the reduction of a wide range of nitroarenes and aliphatic nitro compounds. Here we describe how the modified nanocellulose has a stabilizing effect on the catalyst that enables low loading of the nickel salt pre-catalyst. Ni-B prepared in situ from a methanolic solution was also used to develop a greener and facile reduction of azides, offering a substantially lowered catalyst loading with respect to reported methods in the literature. Both aromatic and aliphatic azides were reduced and the protocol is compatible with a one-pot Boc-protection of the obtained amine yielding the corresponding carbamates. Finally, bacterial crystalline nanocellulose was chosen as a support for the Ni-B catalyst to allow an easy recovery step of the catalyst and its recyclability for new reduction cycles.

Preparation of Nickel Nanocatalysts and Application to the Hydrodechlorination of 3-Chlorophenol under Liquid Phase

Nickel nanoparticles were successfully synthesized via the reduction of nickel salt using ethylene glycol (EG) and sodium borohydride (NaBH4) as reducing agents. These nickel nanoparticles were then loaded on the supports as Ni-X (X = vanadium phosphorus oxides (VPO), TiO2, and ZnO) in high loading yield. The optical properties of these catalysts were characterized by UV-vis spectroscopy, the structure of Ni-X was studied by powder X-ray diffraction (PXRD), the distribution of Ni particles in X was studied by transmission electron microscopy (TEM), and the specific surface area of Ni-X was evaluated by N2 adsorption isotherm analysis at 77 K. All results corroborated the loading process. Indeed, TEM image indicated that the nickel nanoparticles size is in the range of 14 ÷ 16 nm and fully loaded into X. The activities of these catalysts were performed on the hydrodechlorination of 3-chlorophenol in the presence of sodium hydroxide as base at atmospheric pressure and at RT. The results showed that Ni-X exhibited high activities up to 98% within 90 min in the case of Ni-ZnO catalyst.

Preparation of Ni2P decorated black phosphorus nanosheets supported on two-dimensional α-zirconium phosphate and its catalysis for hydrodesulfurization of dibenzothiophene

The hybrid material of a novel Ni2P/black phosphorus (Ni2P/BP) supported on two-dimensional α-zirconium phosphate (α-ZrP) was prepared, and its catalytic activity for hydrodesulfurization (HDS) of dibenzothiophene (DBT) was investigated in a batch autoclave reactor. The results indicate that a high yield of BP nanosheets from bulk BP crystals can be easily obtained adopting a freeze-assisted exfoliation method, and Ni2P/BP can be sucessfully synthesized by a facial one-step solvothermal reaction. Through the reaction of the nickel salt with BP nanosheets, Ni2P nanoparticles formed in situ are firmly anchored on the surface of BP, effectively preventing themselves from aggregating. BP is not only used as the phosphorus source for the synthesis of Ni2P, but its superior electron mobility can significantly promote the catalytic HDS activity of Ni2P species. Moreover, the support of two-dimensional α-ZrP nanosheets with a large specific surface area has a strong structure and adjustable performance, which greatly improves the stability and service life of the catalyst. With the Ni/P molar ratio of 1:2 in the supported Ni2P/BP nanosheets, Ni2P/BP@ZrP has a conversion rate of 87.4% for the HDS reaction of DBT within 6 h at 260 ℃, much higher than the traditional NiMo/Al2O3 catalyst (65.6%), showing a good promising application to industrial catalytic desulfurization.

The Effect of Ni Precursor Salts on Diatomite Supported Ni-Mg Catalysts in Methanation of CO2

This study is aimed to investigate the effect of Ni precursor salts on the properties (textural, phase-structural, reducibility, and basicity), and catalytic performance of diatomite supported Ni-Mg catalyst in methanation of CO2. The NiMg/D-X catalysts derived from various nickel salts (X = S-sulfamate, N-nitrate or A-acetate) were synthesized by the precipitation-deposition (PD) method. The catalysts were characterized by N2-physisorption, XRD, TPR-H2, and TPD-CO2 techniques. The different catalytic activity (conversion) and selectivity, observed in CO2 methanation carried out under relatively mild conditions (atmospheric pressure; temperatures: 250-450 °C) are related and explained by the difference in textural properties, metallic Ni-crystallite size, reducibility, and basicity of studied catalysts. The results showed that catalyst derived from Ni-nitrate salt (NiMg/D-N) is more suitable for the preparation of efficient catalyst for CO2 methanation than its counterparts derived from sulfamate (NiMg/D-S) or acetate (NiMg/D-A) nickel salt. The NiMg/D-N catalyst showed the highest specific surface area and total basicity, and the best catalytic performance with CO2 conversion of 63.3 % and CH4 selectivity of 80.9 % at 450 °C.

Virucidal Action Mechanism of Alcohol and Divalent Cations Against Human Adenovirus

Hygiene and disinfection practices play an important role at preventing spread of viral infections in household, industrial and clinical settings. Although formulations based on >70% ethanol are virucidal, there is a currently a need to reformulate products with much lower alcohol concentrations. It has been reported that zinc can increase the virucidal activity of alcohols, although the reasons for such potentiation is unclear. One approach in developing virucidal formulations is to understand the mechanisms of action of active ingredients and formulation excipients. Here, we investigated the virucidal activity of alcohol (40% w/v) and zinc sulfate (0.1% w/v) combinations and their impact on a human adenovirus (HAdV) using, nucleic acid integrity assays, atomic force microscopy (AFM) and transmission electron microscopy (TEM). We observed no difference in virucidal activity (5 log10 reduction in 60 min) against between an ethanol only based formulation and a formulation combining ethanol and zinc salt. Furthermore, TEM imaging showed that the ethanol only formulation produced gross capsid damage, whilst zinc-based formulation or formulation combining both ethanol and zinc did not affect HAdV DNA. Unexpectedly, the addition of nickel salt (5 mM NiCl2) to the ethanol-zinc formulation contributed to a weakening of the capsid and alteration of the capsid mechanics exemplified by AFM imaging, together with structural capsid damage. The addition of zinc sulfate to the ethanol formulation did not add the formulation efficacy, but the unexpected mechanistic synergy between NiCl2 and the ethanol formulation opens an interesting perspective for the possible potentiation of an alcohol-based formulation. Furthermore, we show that AFM can be an important tool for understanding the mechanistic impact of virucidal formulation.