Nickel Oxide nanoparticles

Abstract Reduced graphene oxide (RGO) is functionalized with glucose and nickel oxide for the supercapacitor application. The RGO layers intercalated by glucose create microspores inside the composite after thermal treatment at 500 °C, and the addition of nickel oxide reduces impedance of the composite, resulting in synergetic effects on the supercapacitor performance. That is, the specific capacitance of the composite is about five times higher than that of the RGO which has no glucose nor nickel oxide. The ternary composite also exhibits high performance of electric double layer capacitor (EDLC) and maintains the same specific capacitances up to 5,000 cycles, providing excellent cyclic stability. The ternary composite of the high EDLC performance, therefore, could be a good candidate of the supercapacitor electrodes.

High surface area carbon porous materials (CPMs) synthesized by the
direct template method via self-assembly of polymerized phloroglucinol-formaldehyde
resol around a triblock copolymer template were used as supports for nickel nanoparticles
(Ni NPs). The Ni/CPM materials fabricated through a microwave-assisted heating
procedure have been characterized by various analytical and spectroscopic techniques,
such as X-ray diffraction, field emission transmission electron microscopy, vibrating
sample magnetometry, gas physisorption/chemisorption, thermogravimetric analysis, and
Raman, Fourier-transform infrared, and X-ray photon spectroscopies. Results obtained
from ultraviolet−visible (UV−vis) spectroscopy demonstrated that the supported Ni/
CPM catalysts exhibit superior activity for catalytic reduction of organic dyes, such as
methylene blue (MB) and rhodamine B (RhB). Further electrochemical measurements
by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) also revealed that
the Ni/CPM-modified electrodes showed excellent sensitivity (59.6 μA μM−1 cm−2) and
a relatively low detection limit (2.1 nM) toward the detection of Hg(II) ion. The system
has also been successfully applied for the detection of mercuric ion in real sea fish samples. The Ni/CPM nanocomposite
represents a robust, user-friendly, and highly effective system with prospective practical applications for catalytic reduction of
organic dyes as well as trace level detection of heavy metals.

Nickel Oxide (NiO) nanoparticles have been synthesised by self-propagating low temperature Combustion synthesis method using Nickel salt with polyethylene glycol as fuel. As synthesized NiO nanoparticles was Characterized by employing Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy dispersive X-ray microanalysis studies (EDAX) techniques and X-ray diffraction (XRD) confirmed the formation of NiO nanoparticles in the range 20 to 40 nm.
SEM images clearly shows the NiO particles are in Nano size

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Monitoring of hazardous gases is nowadays very important, since the urbanized environment is more subject to this kind of pollutants. Therefore, a capillary network of small gas sensors capable to check the quality of the environment is necessary. Metal oxide gas nanosensors are small economic devices that can be easily integrated in any context, however they unfortunately lack of selectivity. We present an approach using hydrothermally grown nickel oxide nanowires working at different temperatures and creating a virtual sensors array, thus exploiting the thermal fingerprints (sensor response as a function of temperature) of the gases. Using only one nanostructured material (nickel oxide) and different machine learning techniques, the system can easily discriminate any of 7 harmful gases (C 2 H 5 OH, H 2 , CO, LPG, CO 2 , NH 3 and H 2 S, all of them reducing gases) with an accuracy of 100%. Furthermore, the nanosensor also evaluates the gas concentration with an average error lower than 15%. Our results show that, exploiting thermal fingerprints from a temperature gradient, single metal oxide resistive nanosensors can efficiently discriminate specific hazardous gases.

Nickel oxide on directly grown carbon nanofibers (CNF-NiO) electrodes were fabricated and used as cathodes for hydrogen production by water electrolysis and as electrode materials for supercapacitors. Tafel polarization from the CNF-NiO electrodes showed an improvement in the hydrogen evolution reaction. This was attributed to the increment of the electrochemi-cally active surface area, conductivity, and the synergy effects between the nickel oxide, carbon nanofibers, and nickel foam substrate. When used for supercapacitor applications, these electrodes showed a specific capacitance of ca. 776.20 ± 26 mF cm −2 at a current density 3 mA cm −2. These electrodes prepared using a facile method also exhibited a capacitance retention of 89% even after 3000 cycles with a coulombic efficiency of 89% when cycled at 20 mA cm −2. Considering the simplistic approach of the electrode preparation, the stability, and the capacitance, this method opens an avenue to try various metal oxide deposit on the directly grown CNF template. Graphical abstract Potentiostat Counter Electrode (CE): Graphite Reference Electrode (RE): SCE Argon Purging Working Electrode (WE) V Carbon nanofiber (CNF) CNF substrate C NF substrate Ni-oxide layer Precursor coats (Ni)

Activated carbon monolith porous electrodes of a supercapacitor prepared by carbonization
(N
2) and activation (CO
2
) methods from KOH-treated pre-carbonized biomass fibers were deposited
with nickel oxide at varying dipping time (from 0 to 60 min) in 20 mL of 0.1 mol Ni(NO
3
)
2
and 20 mL
of  0.2  mol  NaOH  solution  followed  by  annealing  at  300°C  for  2  h.  N
2
adsorption-desorption
characterization results confirmed the porous characteristic of the bare electrodes (surface area 1656
m
2
g
-1
). Energy dispersive X-ray (EDX) analysis and  field  emission  scanning  electron  microscopy
(FESEM) results showed the deposited nickel oxide nanoparticles were homogeneously distributed
on the surface of electrodes and X-ray diffraction results revealed the semicrystalline phase of the
deposited particles. Electrochemical impedance spectroscopy  characterization of the supercapacitor
cells  fabricated  using  these  electrodes  showed  that  the  optimum dipping  time  (15  –  45  min)  can
improve the supercapacitor specific capacitance and equivalentseries resistance by 27 – 30 % and 6 –
34 %, respectively.

"Resonant soft x-ray Raman scattering measurements on NiO have been made
at photon energies across the Ni 2p absorption edges. The details of the
spectral features are identified as Raman scattering due to d–d and chargetransfer
excitations. The spectra are interpreted within the single-impurity
Anderson model, including multiplets, crystal-field and charge-transfer effects.
At threshold excitation, the spectral features consists of triplet–triplet and
triplet–singlet transitions of the 3d8 configuration. For excitation energies
corresponding to the charge-transfer region in the Ni 2p x-ray absorption
spectrum of NiO, the emission spectra are instead dominated by charge-transfer
transitions to the 3d9L−1 final state. Comparisons of the final states with other
spectroscopical techniques are also made."

The transmittance and absorbance data of nickel oxide films are crucial in determining it's optical properties. Selection of substrate is important for a greater understanding of optical constants and properties of a material. In view of this Nickel oxide films were deposited on Quartz substrates and it's properties are compared with Nickel oxide films deposited on glass. We show the difference in optical constants measured for Nickel oxide thin film deposited on glass and quartz substrates.

This work reports the growth of layered nickel hydroxide/gold films by sol-gel and dip-coating methods to obtain colored films for applications in switchable optical devices. The nickel and gold-based films were deposited on mica and glass plates from alcoholic sols. The distribution of electron density inhomogeneities (voids, nickel and gold particles) in the films was determined by means of small angle X-ray scattering (SAXS). The SAXS measurements were used to determine the nickel and gold particle sizes and to give guidelines to the appropriate chemical route to deposit homogeneous colored films. X-ray diffraction (XRD) was used to monitor the crystalline properties. Transmission electron microscopy (TEM) was used to observe the nanostructure of the gold particles and atomic force microscopy (AFM) to analyze the film surface. Spectral transmission was used to investigate the optical properties in these different layered systems, which present an absorption band in the visible region due to the gold aggregates. The composite material is deep blue. The analyses of SAXS data, TEM and AFM pictures are consistent, i.e., the formed Au particles are polydisperse in size and their clustering depends on the NiOx Hy layer. The Au particles are polycrystalline, with [111]-preferred orientation, as determined by XRD. The nickel oxy-hydroxide matrix is amorphous.

The inexpensive sources of fossil fuels in the world are limited, and will deplete soon because of the huge demand on the energy and growing economies worldwide. Thus, many research activities have been focused on the non-fossil fuel based energy sources, and this will continue next few decades. Water splitting using photocatalysts is one of the major alternative energy technologies to produce hydrogen directly from water using photon energy of the sun. Numerous solid photocatalysts have been used by researchers for water splitting. In the present study, nickel oxide and strontium titanata were chosen as photocatalysts for water splitting. Poly (vinyl pyrrolidone) (PVP) was incorporated with nickel oxide [Ni2O3] (co-catalyst), while poly (vinyl acetate) (PVAc) was mixed with titanium (IV) isopropoxide [C12H28O4Ti] and strontium nitrate [Sr(NO3)2]. Then, two solutions were electrospun using coaxial electrospinning technique to generate nanoscale fibers incorporated with NiOx nanoparticles. The fibers were then heat treated at elevated temperatures for 2hr in order to transform the strontium titanata and nickel oxide into crystalline form for a better photocatalytic efficiency. The morphology of fibers was characterized via scanning electron microscopy (SEM), while the surface hydrophobicity was determined using water contact angle goniometer. The UV-vis spectrophotometer was also used to determine the band gap energy values of the nanofibers. This study may open up new possibilities to convert water into fuel directly using the novel photocatalysts.

A novel hierarchical three dimensional (3D) NiO/CdS heteroarchitecture was successfully synthesized by a facile single pot hydrothermal route and characterized by powder X-ray diffractogram, UV-Vis spectroscopy, BET, FE-SEM and TEM. FE-SEM and TEM analysis ...