Ni Nanocomposite Research Articles

Synergistic catalytic effects of the Ni and V nanoparticles on the hydrogen storage properties of Mg-Ni-V nanocomposite

The Mg-5.0 wt%Ni-2.3 wt%V nanocomposite has been produced through reducing NiCl2 with the Mg-V nanoparticles (NPs) prepared by hydrogen plasma metal reaction (HPMR) approach. The in situ formed Ni and V particles of about 15 nm uniformly decorate on the surface of Mg NPs. The Ni NPs transform into Mg2Ni while the V NPs remain unchanged after first hydrogen absorption and desorption cycle at 673 K. They show synergistic catalytic effects on the hydrogen storage properties of Mg-Ni-V nanocomposite. The nanocomposite can absorb 4.6 wt% H2 within 30 min at 473 K and desorb 5.2 wt% H2 within 10 min at 623 K. The activation energies of hydrogenation/dehydrogenation processes are decreased to 52.8 and 85.1 kJ per mol H2, lower than those of the Mg-5.4 wt%Ni nanocomposite of 63.2 and 89.3 kJ per mol H2. The enhanced hydrogen storage performances of the Mg-Ni-V nanocomposite are mainly attributed to the synergistic catalytic effects of the Mg2Ni and V catalysts, and the nanosize effect of Mg NPs on the decrease of the hydrogen diffusion distance.

Greener Synthesis of Reduced Graphene Oxide‐Nickel Nanocomposite: Rapid and Sustainable Catalyst for the Reduction of Nitroaromatics

AbstractAn efficient one‐pot method for the preparation of reduced graphene oxide‐nickel nanocomposite (RGO−Ni) has been developed using L‐ascorbic acid as a greener reducing agent, which simultaneously reduces both graphene oxide and NiII. The nanocomposite was characterized using various analytical techniques such as Fourier Transform Infrared Spectroscopy (FT‐IR), Powder X‐Ray Diffraction analysis(PXRD), Raman, Inductively Coupled Plasma‐Optical Emission Spectroscopy (ICP‐OES), Energy Dispersive X‐ray Spectroscopy (EDS), Scanning Electron Microscopy (SEM), High‐Resolution Transmission Electron Microscopy (HRTEM), X‐ray Photoelectron Spectroscopy (XPS) and surface area measurements. ICP‐OES confirms the presence of 19.7% nickel loading and TEM shows the average size of the particles to be 10 nm. Subsequently, RGO−Ni nanocomposite was used as a sustainable catalyst for the reduction of nitroaromatics to the corresponding amines using NaBH4 in an aqueous methanol medium. A series of aromatic and aliphatic nitro compounds are chemoselectively reduced to amines over other reducible functionalities. RGO−Ni nanocomposite is highly stable, and can be recovered by magnetic separation and recycled for at least five consecutive cycles. The present catalytic system has achieved the dual requirements for reactivity and selectivity in a nitro reduction in short reaction time with minimum nickel load in greener media.

Synthesis and application of conductive polymeric ionic liquid/Ni nanocomposite to construct a nanostructure based electrochemical sensor for determination of risperidone and methylphenidate

In the present study, poly(MImEO8BS)-Ni nanocomposite was synthesized and applied to modify a glassy carbon electrode along with polymeric ionic liquids (PILs). The electrochemical investigation of the modified electrode as well as its efficiency for voltammetric oxidation of risperidone is explained. The electrode was used to study the voltammetric oxidation of risperidone employing cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry and square-wave voltammetry (SWV) as diagnostic techniques. It has been observed that the oxidation of risperidone at the surface of modified electrode occurs at a potential of about 130mV less positive than that of an unmodified glassy carbon electrode. SWV showed a linear dynamic range from 5.0×10−7 to 8.0×10−5M and a detection limit of 7.3×10−8M for risperidone. Moreover, this modified electrode was utilized for simultaneous determination of risperidone and methylphenidate. Finally, the modified electrode was employed for determination of risperidone and methylphenidate in pharmaceutical compounds.

Synthesis of conductive polymeric ionic liquid/Ni nanocomposite and its application to construct a nanostructure based electrochemical sensor for determination of warfarin in the presence of tramadol

In the current study, poly(MImEO8BS)-Ni nanocomposite was synthesized and applied to modify a glassy carbon electrode along with conductive polymeric ionic liquids. The electrochemical investigation of the modified electrode as well as its efficiency for voltammetric oxidation of warfarin is elucidated. The electrode was used to study the voltammetric oxidation of warfarin by employing cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry, and square wave voltammetry (SWV) as diagnostic techniques. It has been observed that warfarin oxidation at the surface of modified electrode occurs at a potential of about 230mV which is less positive than that of an unmodified glassy carbon electrode. SWV demonstrated a linear dynamic range from 1.0×10−6 to 1.0×10−4M and a detection limit of 1.5×10−7M for warfarin. In addition, this modified electrode was utilized for simultaneous determination of warfarin and tramadol. Finally, the modified electrode was employed for determination of warfarin and tramadol in pharmaceutical compounds.

Graphene-coated hybrid electrocatalysts derived from bimetallic metal–organic frameworks for efficient hydrogen generation

This is the first example of a Ni and Mo2C nanocomposite derived from a bimetallicNiMo-MOFthat demonstrates excellent electrocatalytic activity and remarkable durability as long as 10 h for HER under acidic and basic conditions.

Comparative study of mechanical properties of pure nanocrystalline Ni and Ni-Tf nanocomposite

Mechanical properties of nanocrystalline (nc) Nickel (Ni) and Ni-Teflon (Ni-Tf) nanocomposite has been studied in detail using nanoindentation and conventional tensile tests. Nanoindentation tests carried out at room temperature over a range of loading rate exhibited higher hardness for the nanocomposite as compared to the nc-Ni due to Tf dispersion. An increase in strain rate sensitivity (SRS) and decrease in activation volume of the nanocomposite as compared to nc-Ni was also observed. Tensile tests were carried out over a temperature regime of room temperature (RT) to 500°C. Tensile data also showed enhancement of yield stress and ultimate tensile strength up to 150°C. But from 200°C and above, Tf dispersion is unable to provide superior strength over nc-Ni as both the materials show almost similar strength. However, the ductility of the Ni-Tf nanocomposite was observed to be higher at all temperature compared to the pure nc-Ni. SRS was found to increase with temperature while SRS in nanocomposite had higher value below 200°C. The present study reveals that Ni-Tf nanocomposite possess better strength and ductility compared to nc-Ni up to 200°C.

The Enhanced Catalytic Activities of Asymmetric Au-Ni Nanoparticle Decorated Halloysite-Based Nanocomposite for the Degradation of Organic Dyes.

Janus particles (JPs) are unique among the nano-/microobjects because they provide asymmetry and can thus impart drastically different chemical or physical properties. In this work, we have fabricated the magnetic halloysite nanotube (HNT)-based HNTs@Fe3O4 nanocomposite (NCs) and then anchored the Janus Au-Ni or isotropic Au nanoparticles (NPs) to the surface of external wall of sulfydryl modified magnetic nanotubes. The characterization by physical methods authenticates the successful fabrication of two different magnetic HNTs@Fe3O4@Au and HNTs@Fe3O4@Au-Ni NCs. The catalytic activity and recyclability of the two NCs have been evaluated considering the degradation of Congo red (CR) and 4-nitrophenol (4-NP) using sodium borohydride as a model reaction. The results reveal that the symmetric Au NPs participated NCs display low activity in the degradation of the above organic dyes. However, a detailed kinetic study demonstrates that the employ of bimetallic Janus Au-Ni NPs in the NCs indicates enhanced catalytic activity, owing to the structurally specific nature. Furthermore, the magnetic functional NCs reported here can be used as recyclable catalyst which can be recovered simply by magnet.

A Co3O4@MnO2/Ni nanocomposite as a carbon- and binder-free cathode for rechargeable Li–O2batteries

The Co3O4@MnO2/Ni nanocomposite enables the Li–O2battery with 0.5 M lithium bis(trifluoromethanesulfonyl)imide in 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide to operate with a small voltage gap of 0.76 V for 170 cycles of discharge and charge.

Microstructuring of carbon nanotubes-nickel nanocomposite

In this paper, we develop a novel electroplating method for the synthesis of carbon nanotubes (CNTs)-nickel (Ni) nanocomposite, and present the fabrication of a silicon micromirror with the CNTs-Ni nanocomposite beams to evaluate the mechanical stability of the micromirror in terms of resonant frequency. CNTs are pretreated to have positive charges on their surface and added into a Ni electroplating solution to form a CNTs-Ni nanocomposite electroplating suspension. The weight fraction of the CNTs in the electroplated nanocomposite is 2.4 wt%, and the ultramicroindentation hardness is 18.6 GPa. The mechanical strengthening phenomenon is found in the nanocomposite in comparison with a Ni film. Moreover, the addition of CNTs in the nanocomposite beams effectively increases the shear modulus compared with the pure Ni. The maximum variation of the resonant frequency of the micromirror during a long-term stability test is approximately 0.25%, and its scanning angle is approximately 20°. It shows the potential suitability of the CNTs-Ni nanocomposite with proper design for micromechanical element applications.

Hydrogen Storage Properties of a Mg–Ni Nanocomposite Coprecipitated from Solution

Reducing Mg particles to nanoscale and doping with various catalysts are considered as efficient approaches for improving the hydrogen storage properties of Mg/MgH2. It has been established that doping Ni or Mg2Ni into nano-Mg/MgH2 through physical routes remarkably improves the hydrogen sorption kinetics. In this work, a Mg–Ni nanocomposite has been coprecipitated from a tetrahydrofuran (THF) solution containing anhydrous magnesium chloride (MgCl2), nickel chloride (NiCl2), and lithium naphthalide (LiNp) as the reducing agent. TEM observations reveal that Ni nanoparticles are distributed homogeneously on the surface of those larger Mg particles with sizes ranging from 10 to 20 nm in the nanocomposite. It is observed that γ-MgH2 phase appears when the nanocomposite is hydrogenated at temperatures below 225 °C. Pressure–composition–temperature (PCT) measurements reveal that the Mg–Ni nanocomposite has superior hydrogen storage properties over the pure Mg prepared using the same method. For instance, the Mg–Ni nanocomposite can absorb 85% of its maximum hydrogen capacity within 45 s at 125 °C, and a hydrogen capacity of 5.6 wt % can be obtained within 10 h at room temperature. In addition, the dehydrogenation temperature of the hydrogenated Mg–Ni nanocomposite is also much lower than that of the hydrogenated pure Mg. The hydrogenation and dehydrogenation enthalpies of the Mg–Ni nanocomposite are determined to be −70.0 and 70.7 kJ/mol H2, slightly lower than those for the reduced pure Mg. The excellent hydrogen sorption properties of the Mg–Ni nanocomposite can be attributed to the nanosize effect of Mg particles and the gateway effect of Mg2Ni formed in the composite after hydrogenation/dehydrogenation cycles.

Pulse electrodeposited Ni-Gd2O3 nanocomposite electrode as electrocatalysts for ethanol electro-oxidation

In this work, pure Ni and Ni-Gd2O3 nanocomposites are deposited on mild steel surface using nickel sulphamate electrolyte by pulse electrodeposition method. The effect of Gd2O3 nano particles concentration on the preferred orientation of Ni-Gd2O3 nanocomposite was studied by X-ray diffractrometer. The surface morphology, surface topography and chemical composition of deposited pure Ni and Ni-Gd2O3 nanocomposite was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy (EDAX) respectively. The electrocatalytic activity of the pure Ni and Ni-Gd2O3 nanocomposite electrodes for the electro-oxidation of ethanol was studied by cyclic voltammetry and chronoamperometry. The results showed that, Ni-Gd2O3 nanocomposite electrode increases the electrocatalytic activity towards ethanol electro-oxidation compared with pure Ni. However, the chronoamperometry experiments revealed that the stability of the Ni-Gd2O3 composite electrodes with time is found to be equivalent to pure Ni electrode.

Effect of the type of Pt precursor on Pt–Ni nanostructures for electro-oxidation of ammonia

The properties of Pt–Ni nanostructures were successfully controlled by employing different Pt precursors in the preparation of Pt–Ni nanocomposites, which were synthesized by a co-reducing Pt and Ni precursors. Pt–Ni nanostructures were obtained by leaching Ni species from the Pt–Ni nanocomposite. The use of H2PtCl6 as a precursor yielded aggregated small Pt particles, while [Pt(NH3)4]Cl2 yielded large hollow Pt nanostructures. A possible mechanism leading to the morphological difference between the two structures was suggested. Owing to a higher electrochemically active surface area and a favorable surface structure, hollow Pt nanostructures from the [Pt(NH3)4]Cl2 precursor showed significantly better performance in ammonia oxidation than the aggregated Pt particles resulting from the H2PtCl6 precursor.

Microstructural development and its mechanism of mechanical alloyed nanocrystalline W–10Ni alloy reinforced with Y2O3 nanoparticles

The work presented here deals with the mechanical alloying (MA) preparation of W–10Ni matrix nanocomposites reinforced with nanometer-sized Y2O3 particles, using micrometer-scaled W, Ni (10wt.%), and Y2O3 (2.5wt.%) powder as the starting materials. The X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), and laser particle size analyzer were used to characterize the changes of constitutional phases, chemical compositions, and microstructural features of the nanocomposite powder during MA process. It revealed that after 10h milling, the Ni element was found to diffuse into the W lattice continuously, leading to the formation of the W–Ni solid solution. The powder particles experienced a successive morphological change during milling, i.e., preliminarily refined (10h)–significantly coarsened (20h)–continuously refined (35h)–slightly coarsened (45h), due to the alternant predomination of the fracturing and cold welding mechanisms. The 35h milled Y2O3/W–Ni nanocomposite powder had the most homogeneous and refined particle morphology, showing a narrow size distribution (D10=0.46μm, D25=0.63μm, D50=0.83μm, D75=1.04μm, and D90=1.24μm) and a significantly elevated specific surface area of 3108.21m2/kg. The average crystallite size of the W–Ni solid solution matrix of the 35h milled nanocomposites was 12.5nm and the mean size of Y2O3 reinforcing particles was less than 25nm, exhibiting the typical nanostructures for both matrix and reinforcing phase. The spherical nanometer-sized Y2O3 reinforcing particles had the coherent interfacial structure with the W–Ni matrix. The underlying mechanisms for the phase change and microstructural evolution during MA of Y2O3/W–Ni nanocomposites were also proposed.

Optimization of process parameters for synthesis of silica–Ni nanocomposite by design of experiment

The optimum combination of experimental variable, temperature, time of heat treatment under nitrogen atmosphere and amount of Ni-salt was delineated to find out the maximum yield of nanophase Ni in the silica gel matrix. The size of Ni in the silica gel was found to be 34 and 45 nm for the two chosen compositions, respectively. A statistically adequate regression equation, within 95% confidence limit was developed by carrying out a set of active experiments within the framework of design of experiment. The regression equation is found to indicate the beneficial role of temperature and time of heat treatment.

Fast and efficient reduction of nitro aromatic compounds over Fe3O4/β-alanine-acrylamide-Ni nanocomposite as a new magnetic catalyst

In this study, Ni nanoparticles incorporated β-alanine-acrylamide (Ala-AA) was successfully prepared by a simple method. The obtained magnetic nanocomposite exhibited excellent activity as a new heterogeneous magnetic catalyst for the reduction of a number of nitro aromatic compounds under mild conditions along with high level of reusability.

Creep in an electrodeposited nickel

This paper reports the experimental results on the creep behavior of electrodeposited ultrafine-grained nickel and its particle-reinforced nanocomposite. The objective of this research was to further improve the knowledge of the creep behavior of monolithic nickel and to explore the role of nano-sized SiO2 particles in the potential creep strengthening of electrodeposited Ni nanocomposite. The creep behavior and microstructure of the pure ultrafine-grained nickel and its nanocomposite reinforced by 2 vol% nano-sized SiO2 particles were studied at temperatures in the range from 293 to 573 K and at the applied tensile stresses between 100 and 800 MPa. The results indicate that the creep resistance of the nanocomposite may be noticeably improved compared to the monolithic nickel due to the interaction of the particles with dislocation motion. It was found that the applied stress interval can be divided into lower and higher stress intervals corresponding to dislocation (power-law) and exponential creep regions, respectively. Analysis of the creep data leads to the suggestion that the creep behavior of both electrodeposited nickel and its nanocomposite in power-law region may be grain boundary controlled. However, the mechanism responsible for the observed creep behavior at lower temperatures and the highest stresses is still not well established.

Synthesis of carbon nanotube/Ni nanocomposite film by electrophoresis and electroless deposition without Pd pretreatment

Here we report the fabrication of carbon nanotubes (CNTs)/Ni nanocomposite film by electrophoretic deposition (EPD) and subsequent electroless deposition. The present technique requires no pretreatment with expensive Pd species for activation of the surface of CNTs. The EPD bath was modified with NiSO4·6H2O to form Ni clusters on the surface of CNTs. As a result, a thin Ni layer (6nm thickness) was fabricated on CNTs, forming a CNT/Ni nanocomposite film with a thickness of 5–10μm. The fabricated CNT/Ni film had nanoporous structure and exhibited electric double layer capacity and catalytic activities for decoloration of methyl orange.

SWCNT growth from C:Ni nanocomposites

AbstractCarbon:nickel (C:Ni) nanocomposite thin films deposited by ion beam co‐sputtering were used for catalytic chemical vapor deposition (CVD) growth of single‐walled carbon nanotubes (SWCNTs). The SWCNTs were characterized by scanning electron microscopy and Raman spectroscopy. The approach allows a precise and reproducible control of the catalyst diameter, while the embedding carbon matrix prevents the particles from coalescence during catalyst activation and nanotube growth. The SWCNTs obtained from Ni particles with ∼4 nm diameter have a radial breathing mode frequency distribution of 147.5 ± 32 cm−1 and a diameter distribution of 1.6 ± 0.4 nm. Small line widths of the radial breathing mode and ID/IG ratios of 0.05 indicate SWCNTs with a low defect concentration. magnified imageLeft: Scheme of C:Ni nanocomposite based SWCNT synthesis. The dark contrast image regions correspond to the Ni particles. Right: Radial breathing mode Raman spectrum of a structurally highly ordered SWCNT.

Magnetically recyclable Pt/C(Ni) nanocatalysts with improved selectivity for hydrogenation of o-chloronitrobenzene

Abstract Magnetically recyclable Pt/C(Ni) catalysts consisting of Pt nanoparticles on the surface of flower-like C(Ni) nanocomposite was synthesized and tested for the selective hydrogenation of o-chloronitrobenzene to o-chloroaniline at 30 °C and atmospheric pressure. The Pt/C(Ni) catalysts show higher selectivity towards o-chloroaniline than the Pt/C catalyst due to the synergistic effect between Pt and Ni species, which is partly evidenced by the X-ray photoelectron spectroscopy results. Another promising feature of the as-made Pt/C(Ni) catalysts is that they can be easily separated from the reaction system by using an external magnetic field, and this is beneficial for the recycle of noble metal catalysts.

Hydrogen storage properties of Mg–Ce–Ni nanocomposite induced from amorphous precursor with the highest Mg content

The effect of Ce and Ni contents on the glass-forming ability (GFA) of Mg–Ce–Ni system in the Mg-rich corner of Mg–Ce–Ni system is revealed. Ce is more advantageous for the GFA of Mg-rich Mg–Ce–Ni system than Ni, and the lowest Ce content is ∼5 at.% to obtain the fully amorphous alloy. Amorphous alloy with the highest Mg content, Mg90Ce5Ni5, was obtained by melt-spinning. With the amorphous alloy as precursor, nanostructure multi-phases compositae was prepared by crystallizing it in hydrogenation process. The compositae with reversible hydrogen storage capacity of 5.3 wt.% shows much faster kinetics and lower MgH2 desorption activation energy than those of induction-melt Mg90Ce5Ni5 alloy. Both in situ formed nanosized Mg2Ni and CeH2.73 act as effective catalysts and significantly improve the hydrogen storage properties of MgH2.