Size Of Nickel Nanoparticles Research Articles

USAGE OF ACRYLIC ACID BASED POLYMER FOR STABILIZATION OF NICKELINE NANOPARTICLES

In this work, our team synthesized polyacrylic acid-supported Ni nanoparticles and SEM images were shown of polyacrylic acid-supported Ni nanoparticle samples at different magnifications in low electron mode at different voltages. The study examined the solubility of nickel nanoparticles depending on their concentration, and also studied the influence of the activity of acidity and ba-sicity of the medium and the concentration of nanoparticles on the overall distribution of the sus-pension. We have obtained nanoparticles of metallic nickel. To study the effect of an acidic envi-ronment on the dispersion of suspensions of nickel nanoparticles, various solutions with different alkalinity and acidity were created. Consequently, it was observed that the acidity level of the medium has minimal influence on the average particle size within suspensions of identical concen-trations. The size of nickel nanoparticles remains highly diminutive and can be readily tailored by adjusting both the polymer type and concentration in each specific context. At selected polymer concentrations that provide the same number of monofragments, PAA is the best stabilizer. Keywords: PAA, solution, suspension, nanoparticles, TEM.

PHYSIOLOGICAL AND ANATOMICAL RESPONSES OF COMMON BEAN (PHASEOLUS VULGARIS L.) TO NICKLE NANOPARTICLES FOLIAR SPRAY

Nickel is an essential nutrient for plant growth with low concentrations, its excessive amounts in soil above threshold values could be cause in toxicity. The main objectives of the present research were to determine the effects of nickel nanoparticles foliar spray with 20, 40 and 70 nm diameter on the physiological characters and anatomical aspects of Phaseolus vulgaris L. plants. Lowest reduction significantly (P < 0.01) in root and shoot biomass was recorded due to in 70 nm; the measurements 0.08 and 0.05 g per plant and highest root: shoot; 0.65 as compared with control treatment. As well as the lowest conserved water content; 40% was observed in size 70 nm. While in size 40 nm Nickle nanoparticles increased chlorophyll a, b, total and carotenoids pigment contents. When the nickel nanoparticles size increased, the shoot and root tissue Ni concentrations also increased. However, the rate of Ni in root was greater than that observed in the shoot. While the Mn, Fe, Cu and Zn levels decreased due to applying nickel nanoparticles. The size of nanoparticles effects on the anatomical characteristics or structures such as stem, and leaf, also effects on the size of stomata.

Hydrothermal gasification of glucose for H2 production using Ni–Al2O3 nanocatalyst

Hydrothermal gasification of glucose for H2 production using Ni–Al2O3 nanocatalyst

Structure-controlled graphene-encapsulated nickel nanoparticle with tailored work function to steer chemoselective hydrogenation of nitroarenes

Structure-controlled graphene-encapsulated nickel nanoparticle with tailored work function to steer chemoselective hydrogenation of nitroarenes

Thermal and Electro-Optical Properties of Size Dependent Nickel Nanoparticle Doped Blue Phase Liquid Crystals

In present work, effect of nickel nanoparticles size on blue phase stabilization and its electric-optical properties has been demonstrated in In plane switching (IPS) configuration of liquid crystal cells. Variation in phase transitions and their textural behavior after doping of nickel nanoparticles of sizes 20nm and 40nm in pure blue phase liquid crystal was observed under polarizing optical microscope in IPS cells and compared the results with already reported data in indium tin oxide coated glass plate cells. Blue phase range has been widened after doping of both size of nickel nanoparticles and maximum BP range found is 6.5oC and 6.3oC in 20nm and 40nm-BPLC composites respectively in IPS cells. Voltage-transmission data has been taken for pure blue phase liquid crystal and nickel nanoparticles doped blue phase liquid crystal systems at a particular frequency and further various electro-optical parameters have been measured.

Nanoarchitectonics of Ni/CeO2 Catalysts: The Effect of Pretreatment on the Low-Temperature Steam Reforming of Glycerol.

CeO2 nanosphere-supported nickel catalysts were prepared by the wetness impregnation method and employed for hydrogen production from glycerol steam reforming. The dried catalyst precursors were either reduced by H2 after thermal calcination or reduced by H2 directly without calcination. The catalysts that were reduced by H2 without calcination achieved a 95% glycerol conversion at a reaction temperature of only 475 °C, and the catalytic stability was up to 35 h. However, the reaction temperature required of catalysts reduced by H2 with calcination was 500 °C, and the catalysts was rapidly inactivated after 25 h of reaction. A series of physicochemical characterization revealed that direct H2 reduction without calcination enhanced the concentration of oxygen vacancies. Thus, the nickel dispersion was improved, the nickel nanoparticle size was reduced, and the reduction of nickel was increased. Moreover, the high concentration of oxygen vacancy not only contributed to the increase of H2 yield, but also effectively reduced the amount of carbon deposition. The increased active nickel surface area and oxygen vacancies synergistically resulted in the superior catalytic performance for the catalyst that was directly reduced by H2 without calcination. The simple, direct hydrogen reduction method remarkably boosts catalytic performance. This strategy can be extended to other supports with redox properties and applied to heterogeneous catalytic reactions involving resistance to sintering and carbon deposition.

Effect of Nanoparticle Size on the Mechanical Strength of Ni-Graphene Composites.

The effect of the size of nickel nanoparticles on the fabrication of a Ni–graphene composite by hydrostatic pressure at 0 K followed by annealing at 1000 and 2000 K is studied by molecular dynamics simulation. Crumpled graphene, consisting of crumpled graphene flakes interconnected by van der Waals forces is chosen as the matrix for the composite and filled with nickel nanoparticles composed of 21 and 47 atoms. It is found that the main factors that affect composite fabrication are nanoparticle size, the orientation of the structural units, and temperature of the fabrication process. The best stress–strain behavior is achieved for the Ni/graphene composite with Ni nanoparticle after annealing at 2000 K. However, all of the composites obtained had strength property anisotropy due to the inhomogeneous distribution of pores in the material volume.

Tuning Metal–Support Interactions on Ni/Al2O3 Catalysts to Improve Catalytic Activity and Stability for Dry Reforming of Methane

Ni-based catalysts supported on alumina derived from the pseudo-boehmite prepared by the impregnation method were employed for catalytic dry reforming of methane reaction at the temperature of 550–750 °C. The effect of calcination temperature on physicochemical properties such as the Ni dispersion, reduction degree, nickel crystallite sizes, and metal–support interaction of the catalysts was investigated. The characterization results show that increasing the catalyst calcination temperature leads to the formation of nickel-alumina spinel, which enhances the metal–support interaction and increases the reduction temperature. The nickel nanoparticle size decreases and the effective dispersion increases with the increasing calcination temperature from 450 °C to 750 °C due to the formation of nickel aluminate. The catalyst calcined at 750 °C exhibits the highest CH4 and CO2 conversion owing to the small Ni0 active sites and high Ni dispersion. In a 200 h stability test in dry reforming of methane at 700 °C, the Ni/Al2O3-750 catalyst exhibits excellent catalytic stability and anti-coking ability.

Remarkably efficient and stable Ni/Y2O3 catalysts for CO2 methanation: Effect of citric acid addition

The influence of the addition of citric acid on the xCA-Ni/Y 2 O 3 catalyst was explored. The size-dependent reactivity by varying the citric acid additions can be correlated with the metal support interaction and charge transfer from Y 2 O 3 to Ni. More abundant basic and metallic Ni sites play a synergistic effect in CO 2 methanation. Monodentate carbonates and formates are identified to be the important intermediates species in formate route. • The addition of citric acid improves the Ni dispersion and CO 2 methanation of Ni/Y 2 O 3 catalyst. • 12CA-Ni/Y 2 O 3 presents 92 % CO 2 conversion and 100 % CH 4 selectivity at 350 °C. • The size-dependent reactivity correlated with the metal support interaction and charge transfer from Y 2 O 3 to Ni. • More abundant basic and metallic Ni sites play a synergistic effect in CO 2 methanation. • Monodentate carbonates and formates are the important intermediates species in formate route. Citric acid has been investigated for preparing the highly dispersed nickel catalysts on Y 2 O 3 support. A highly enhanced methanation activity with the high CO 2 conversion of 92 % and CH 4 selectivity of 100 % was obtained over Ni/Y 2 O 3 with optimum addition of citric acid at 350 °C. The citric acid additives during the preparation are found to influence the size of nickel nanoparticles and the interaction of metal and support, as estimated by various techniques, which, in turn, to correlated with the catalytic performance. In situ DRIFTS spectra further indicate the importance of small Ni particles on formation of carbonates and formate species as key intermediates and the subsequent hydrogenation of those species into methane. This study proposes that the Y-O-Ni interfacial structure formed by the strong Ni and Y 2 O 3 interaction at high citric acid addition is of prime importance for the formation of methane, benefiting from the more abundant basic sites and metallic Ni to enable CO 2 activation and hydrogenation of key intermediates by effective H 2 dissociation respectively. This work provides a new design strategy for developing highly efficient composite CO 2 methanation catalysts by control of the metal particle size and charge transfer via metal/support interface.

Highly efficient transfer hydrogenation of carbonyl compounds over supported nickel and palladium nanoparticles

AbstractIn this work, metal nanoparticles were successfully synthesized through the reduction of metal salts using reducing agents such as: ethylene glycol (EG) and sodium borohydride (NaBH4). These metal nanoparticles were impregnated into the supports M‐X (M = Ni, Pd; X = Bent, C, Zeolite, and Al2O3) in high yield. The physio‐chemical properties of these catalysts were characterized by various techniques such as UV‐Vis spectroscopy, powder X‐ray diffraction (PXRD), Transmission electron microscopy (TEM) and the specific surface area of M‐X was evaluated by N2 adsorption isotherm analysis at 77 K. All results corroborated the loading process. Literally, TEM images indicated that the palladium and nickel nanoparticles size are 6 and 13 nm, respectively. The efficiency of these catalysts was performed on the transfer hydrogenation of various carbonyl substrates in the presence of potassium hydroxide at atmosphere pressure. The results showed that both nickel and palladium supported X catalysts exhibited high activities over 99 % within 60 min in the presence of potassium hydroxide.

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.

Dual-reductant synthesis of nickel nanoparticles for use in screen-printing conductive paste

This study presents a systematic study in which sodium borohydride and hydrazine were used successively as reducing agents for the synthesis of nickel nanoparticles in an aqueous medium. The size of nickel nanoparticles could be controlled ranging from 11 to 48 nm by adjusting the concentration of hydrazine and the reaction temperature. A product yield of synthesized nanoparticles could achieve as high as 86.5%. As alternatives to silver pastes in some applications, nickel pastes have attracted growing interest because of the lower cost. By the use of nickel nanoparticles as fillers of the conductive pastes, low temperature sintering can be achieved. To avoid film cracking and to improve conductivity, bimodal screen-printing pastes containing different weight ratios of nickel microparticles and nanoparticles were prepared. A micro-to-nanoparticle weight ratio of 2 was found to be the optimal ratio for the nickel paste formulation, resulting in a volume resistivity of 122 μΩ∙cm for a printed film after sintering at a targeted temperature of 600 °C.

Design of a carbon-resistant Ni@S-2 reforming catalyst: Controllable Ni nanoparticles sandwiched in a peasecod-like structure

Abstract Ni-based catalysts for dry reforming of methane (DRM) suffer from the issue of carbon deposition and sintering. In this study, ultrafine nickel nanoparticles (NPs) embedded in the microporous silicalite-2 (S-2) with a peasecod-like structure was prepared by a facile one-pot approach. The size of Ni NPs (ca. 2, 4, 6 and 8 nm) can be precisely controlled by the degree of Ni-O-Si copolymerization. The obtained Ni@S-2 catalyst with Ni NPs size of 2.6 nm exhibited superior activity and stability with no carbon deposition under 650 °C, CH4:CO2 = 1:1 for 50 h. The layered walls of micropores of S-2 posted steric physical barriers against the migration of Ni NPs. Meanwhile, the strong interaction between active Ni and substrate (Ni-O-Si) provided chemical confinement for anti-sintering. This dual physical-chemical confinement strategy to synthesize catalyst with active Ni° sandwiched between layers of tetrahedral SiO4 provides a promising technique for designing other stable metal nanocomposites.

Highly active carbon-supported Ni catalyst prepared by nitrate decomposition with a sacrificial agent for the hydrogen oxidation reaction in alkaline medium

Abstract Ketjenblack EC-600 JD supported Ni/C electrocatalysts with a nickel content of 50 and 60 wt% were prepared by impregnation with either Ni(OAc)2 or a mixture of Ni(OAc)2 and Ni(NO3)2 precursors, followed by freeze-drying and reduction with H2. XRD, TEM and cyclic voltammetry were applied for characterizing the catalysts. The use of Ni(OAc)2 as a sacrificial agent during decomposition of Ni(NO3)2 allows one to decrease significantly the size of nickel nanoparticles (from 37 to 12 nm) at a very high metal loading. Benefiting from the high dispersion and high specific activity, 60 % Ni/Ketjenblack EC-600 JD possesses remarkable mass activity (7 A∙g−1Ni) in the hydrogen oxidation reaction in an alkaline electrolyte.

Efficient and Selective Ni/Al2O3–C Catalyst Derived from Metal–Organic Frameworks for the Hydrogenation of Furfural to Furfuryl Alcohol

Currently, precious metal catalysts or toxic copper-chromium catalysts are widely used in the catalytic hydrogenation of furfural. In this study, the selective hydrogenation of furfural to furfuryl alcohol was performed over alumina-carbon matrix embedded Ni nanoparticles catalyst. The Ni-loaded metal organic framework precursors were synthesized by reverse microemulsion method (water in oil), then the Ni/Al2O3–C catalysts were obtained by pyrolysis under a nitrogen atmosphere. Various characterizations including XRD, XPS, SEM, TEM, TPR, TPD and TG were carried out to reveal the microstructure and chemical composition of the prepared samples. The results showed that the hexagonal platelet structure and the smaller nickel nanoparticle size(~ 8 nm) benefits from the alumina–carbon matrix support, which helped the uniform dispersion and prevented it from accumulation at high temperatures. In addition, the catalyst performance was greatly affected by the calcination conditions and metal loading. At optimized operating conditions, 98.7% conversion of furfural and 92% yield of furfuryl alcohol could be achieved over Ni0.15/Al2O3–C catalyst in the liquid phase hydrogenation reaction with a good reusability.

Nickel catalysts supported on silica microspheres for CO2 methanation

Nickel catalysts supported on silica microspheres were prepared by the application of porous resin beads (Amberlite XAD7HP) as hard template using different order of nickel nitrate and tetraethoxysilane (TEOS) introduction. Large nickel oxide nanoparticles distributed over silica microspheres were formed when nickel precursor was introduced directly to the polymer template prior to the silica framework development or added into the silica-polymer composites. On the other hand, an impregnation of as-prepared silica microspheres after template removal led to the formation of small nickel oxide nanoparticles. The catalysts showed hierarchical pore structure. Low-temperature nitrogen adsorption/desorption and photoacoustic Fourier-transform infrared spectroscopy studies revealed slight changes of porosity and surface properties of catalysts affected by the synthesis methods. X-ray diffraction, scanning and transmission electron microscopy, temperature-programmed reduction and hydrogen desorption studies were used for determination of the properties of metallic nickel nanoparticles. It was stated that the activity and selectivity of catalysts in the CO2 methanation reaction was related to the active surface area and the size of nickel nanoparticles. An increase in CO2 conversion and selectivity to methane at low temperatures (220–350 °C) with an increase in active surface area and decrease in nickel crystallite size was observed.

Ni nanoparticles and the Kirkendall effect in dry reforming of methane

Abstract In this study we report a simple preparation technique for Ni/γ-Al2O3 catalysts for the dry reforming of methane (DRM) at 800 °C to produce CO and H2 (synthesis gas). Hard-templating with low and high surface area activated carbon was applied. The produced synthesis gas exhibited a low product ratio of H2:CO [0.04–0.12], due to reverse water-gas shift. After 75 h time on stream (TOS) minimal deactivation of the catalyst could be observed. A rather unusual activity evolution was found involving a sequence of minimum-maximum-plateau. A scheme was suggested, explaining the activity evolution based on the Ni-nanoparticle positioning from being bare or encapsulated by Al2O3. The Al2O3 shell cracks and undergoes restructuring during reaction making more active sites available for the reaction. Superior metal dispersion was achieved with average nickel nanoparticle size at 4.9 ± 1.3 nm. The sintering mechanism was also investigated. Surprisingly, hollow nickel nanoparticles were observed at 25 h TOS due to the nanoscale Kirkendall effect. This diffusion phenomenon between the core, Ni0, and the outer shell, NiO, (Ni2+) lead to pronounced structural and morphological changes of the catalyst.

Size-dependent studies in ferromagnetic nanoparticles dispersed ferroelectric liquid crystal mixtures

ABSTRACTIn the present study, ferromagnetic nickel nanoparticles (NiNPs) of size (~20 nm, 40 nm) into ferroelectric liquid crystal (FLC) mixture has been dispersed and investigated. Effect of size of NiNPs on the electro-optic, dielectric and optical properties of FLC mixture have been studied and discussed. A minor improvement in spontaneous polarisation, rotational viscosity and faster response time in NiNPs-FLC samples than pure FLC is noticed. Goldstone mode of relaxation frequency ~100 Hz is detected in all samples and follow a Debye type relaxation behaviour. In addition, it is observed that size of NiNPs does not have any remarkable effect on relaxation frequency and dielectric strength. A single absorption peak at 363, 362 Hz is also noticed in pure FLC and NiNPs-FLC samples.

Nickel nanoparticle synthesis using Camellia Sinensis as reducing and capping agent: Growth mechanism and photo-catalytic activity evaluation

Recently, the biosynthesis of nanoparticle attracted the attention of scientific community due to its simplicity, ease and eco-friendly nature. In the present study, Camellia Sinensis (C. Sinensis) leaves extract was employed for the synthesis of nickel nanoparticles (NiNPs). The fabricated NiNPs were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) and X-ray diffraction techniques. The photocatalytic activity (PCA) was evaluated by degrading crystal violet (CV) dye. The NiNPs size was in the range of 43.87-48.76nm, spherical in shape and uniformly distributed with magnetization saturation of 0.073 emu/g. The NiNPs showed promising PCA under solar light irradiation. At optimized conditions, up to 99.5% CV dye degradation was achieved. Results revealed that biosynthesis can be adopted for the synthesis of NiNPs in nano-size range since it is simple, cost effective and eco-friendly in nature versus physico-chemical methods.

Effect of size of nickel nanoparticles on hydrogenation of benzene

The catalytic properties of Inerton-supported nickel nanoparticles in benzene hydrogenation have been studied; rate constants of the reaction at different temperatures have been calculated. Activation energy and conversion have been determined, and the effect of size of nickel nanoparticles on their catalytic properties in benzene hydrogenation has been discussed.