NiO Nanostructures Research Articles

Zinc Ion Intercalation/Deintercalation of Metal Organic Framework-Derived Nanostructured NiO@C for Low-Transmittance and High-Performance Electrochromism

Electrochromic materials hold great promise in energy-saving windows of buildings and various functional glasses. When constructing a private space, it is difficult for electrochromic materials to ...

Synthesis and characterization of NiO, MoO3, and NiMoO4 nanostructures through a green, facile method and their potential use as electrocatalysts for water splitting

NiO, MoO3, and NiMoO4 nanostructures were synthesized using a solution combustion method, employing agar as an organic fuel. TGA/DSC and BET analyses showed that the synthesis of NiO and NiMoO4 involved an intense exothermic combustion reaction that resulted in high surface area nanomaterials, with large pore volume and small pore size. XRD confirmed the phase composition and crystallite size of the synthesized materials. The particle size range was 20–40 nm for NiMoO4 and NiO, and 200–350 nm for MoO3. Band gap values of 3.44, 3.13, and 3.18 eV were determined for NiO, MoO3, and NiMoO4, respectively. Raman spectroscopy provided structural information about the synthesized materials, while FTIR results revealed that agar acts as both a metal-ion chelating agent and fuel. XPS confirmed the valence states of the produced materials and purported their purity, while the zeta potential measurements underpinned the stability of the samples in aqueous media. The synthesized materials were tested as potential electrocatalysts in water electrolysis for the oxygen (OER) and the hydrogen evolution reactions (HER) in an alkaline medium. The results demonstrated that NiMoO4 exhibits an excellent electrocatalytic activity in both OER and HER.

Facile synthesis of N-doped hollow carbon nanospheres wrapped with transition metal oxides nanostructures as non-precious catalysts for the electro-oxidation of hydrazine

In the present work, N-doped hollow carbon nanospheres (N-HCNSs) is prepared by direct carbonization of polyaniline-co-polypyrrole (PACP) hollow spheres without template needing. Two different NiO nanostructures (nanosheets and nanowires) are prepared by forming a shell around the N-HCNSs via simple hydrothermal/calcination processes ([email protected] and [email protected]). The morphology and structure of the nanostructures are characterized using field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The prepared nanocomposites are used as catalysts for the electrocatalytic oxidation of hydrazine. The electrocatalytic activities of different electrodes including GCE, N-HCNSs/GCE, NiO-NPs/GCE, [email protected]/GCE and [email protected]/GCE for hydrazine oxidation are compared using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy (EIS) techniques. The obtained results revealed significantly higher electroactive surface area (ECSA), higher catalytic activity, lower over-potential and better stability of [email protected]/GCE toward the hydrazine electro-oxidation. This observation can be related to the different parameters such as the unique nanowires structure with free pores and the enlarged specific surface area, high conductivity of N-HCNSs, and the synergistic effect between NiO and N-HCNSs.

Electrospun fibrous active bimetallic electrocatalyst for hydrogen evolution

Fabricating earth-abundant bifunctional water splitting electrocatalysts with high efficiencies to replace noble metal-based Pt and IrO2 catalysts is in great demand for the development of clean energy conversion technologies. Molybdenum disulfide (MoS2) nanostructures have attracted much attention as promising material for hydrogen evolution reaction (HER). The production of hydrogen gas by help of potential efficient earth abundant metal oxides, and stable electrolysis seems a promising for hydrogen evolution reaction pathway in 1 M potassium hydroxide electrolyte media is a hot research topic in the field for clean energy conversion, renewable energies and storage. Here we propose asystem composed NiO nanostructures and MoS2 deposited on (MoS2@NiO). Here, by hydrothermal method NiO prepared and MoS2@NiO by an electrospinning technique complex, can be used as catalyst to produce a large amount of hydrogen gas bubbles. The NiO nanostructures composite having highest synergistic behavior fully and covered by the MoS2. For the MoS2@NiO nano composite catalyst, experiment applied in 1 M KOH for the production of hydrogen evolution reaction which exhibits distinct properties from the bulk material. Overpotential values recorded low 406 mV and current density 10 mA cm−2 measured. Co-catalysts characterized by using different techniques for deep study as scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Owing to their unique structure, as-prepared nanocomposite exhibited enhanced catalytic performance for HER due to high electroactive surface area and swift electron transfer kinetics. Based on the HER polarization curves at low potential electrochemical to examine the effects of intercalants HER catalytic efficiency. Our findings establish low Tafel slope (44 mV/decade) and the catalyst stable for at least 13 h. This simple exploitation of MoS2@NiO composite catalysts depending on the intended application of their electrochemistry.

Facile preparation and characterization of novel manganese doped nickel oxide based nanostructured electrode materials for application in electrochemical supercapacitors

ABSTRACT Mn doped NiO nanostructured materials with composition Ni1-xMnxO1-δ (where x = 0.01, 0.03, 0.05, 0.07, 0.09) (MNO) were prepared by simple facile chemical synthesis route. The structural, particulate and microstructural characteristics of the Mn-doped NiO nanostructures were studied by studied by XRD, FTIR, particle size analysis, EDAX, SEM and HRTEM techniques. The XRD peaks of all the materials were indexed to the face-centred cubic (FCC) crystalline structure. FTIR spectra revealed the presence of NiO bending vibration mode between 432.07 to 492.83 cm-1. Particle size patterns and SEM photographs confirmed the presence of nanosized grains apart from few bigger sized grains. The diameter of grains was mostly found to be in the range of 30.04 to 591.16 nm. Presence of appropriate composition of elements was confirmed by EDAX data. Polycrystalline behaviour of Ni0.95Mn0.05O1-δ was exhibited by HRTEM data. The electrochemical phenomena of Ni1-xMnxO1-δ were studied by cyclic voltammetry (CV), galvanostatic charge – discharge and electrochemical impedance measurements in 6 M KOH aqueous solution. Among the samples studied, Ni0.95Mn0.05O1-δ electrode exhibited maximum specific capacitance of 369.6 Fg-1 at a current density of 0.5 Ag-1. From the characterization data, Mn-doped NiO nanostructures appear to be the good electrode materials for electrochemical supercapacitor applications.

Optical and Electrochemical Applications of Li-Doped NiO Nanostructures Synthesized via Facile Microwave Technique

Nanostructured NiO and Li-ion doped NiO have been synthesized via a facile microwave technique and simulated using the first principle method. The effects of microwaves on the morphology of the nanostructures have been studied by Field Emission Spectroscopy. X-ray diffraction studies confirm the nanosize of the particles and favoured orientations along the (111), (200) and (220) planes revealing the cubic structure. The optical band gap decreases from 3.3 eV (pure NiO) to 3.17 eV (NiO doped with 1% Li). Further, computational simulations have been performed to understand the optical behaviour of the synthesized nanoparticles. The optical properties of the doped materials exhibit violet, blue and green emissions, as evaluated using photoluminescence (PL) spectroscopy. In the presence of Li-ions, NiO nanoparticles exhibit enhanced electrical capacities and better cyclability. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results show that with 1% Li as dopant, there is a marked improvement in the reversibility and the conductance value of NiO. The results are encouraging as the synthesized nanoparticles stand a better chance of being used as an active material for electrochromic, electro-optic and supercapacitor applications.

Chemical synthesis of NiO nanostructure by surfactant-assisted sol–gel methodology for urea electrocatalytic oxidation

NiO-nanoparticles were chemically designed via surfactant-assisted sol–gel methodology and investigated in terms of FESEM, BET, TEM, and XRD techniques which indicate the successful preparation of NiO-NPs. The electrocatalytic oxidation of urea was studied in the three-electrode cell to evaluate the efficiency of NiO-NPs material for urea electro-oxidation in the KOH medium. The as-prepared NPs demonstrated improved electrocatalytic oxidation of urea at various urea doses from 0.01 to 2.0 mol/l. The excellent electrocatalytic activity could be related to the successful synthesis of NiO-NPs which can easily form NiOOH and generate electrons from urea-bonds during the electrochemical process. This work will provide novel anode catalysts for urea fuel-cells.

Structural, electrochemical and optical properties of hydrothermally synthesized transition metal oxide (Co3O4, NiO, CuO) nanoflowers

In this work, structural, electrochemical and optical properties of the flower-like Co3O4, NiO and CuO nanostructures were investigated. Co3O4, NiO and CuO nanoflowers were prepared using hydrothermal method. Fourier transform infrared spectroscopy was used in the confirmation of the chemical composition of the nanostructures. X-ray diffraction (XRD) was used in the analysis of crystal structures that peaks observed in the XRD analysis confirms good crystallinity of the nanoflowers. Scanning electron microscopy analysis was used to illustrate the flower-like structure of the nanostructures. Cyclic voltammetry (CV) was used in the assessment of the electrochemical properties. It was seen that flower-like Co3O4, NiO and CuO nanostructures have enhanced electrochemical properties. Using CV results, redox reaction processes of the Co3O4, NiO and CuO nanoflowers were determined. Diffusion constants were determined and NiO nanoflowers found to have the highest diffusion constant among those. Nyquist and Bode diagrams were evaluated. Energy band gaps of Co3O4, NiO, CuO nanoflowers were calculated which were found to be 2.10 eV, 2.25 eV and 3.71 eV, respectively.

Fabrication of a propanol gas sensor using p-type nickel oxide nanostructures: The effect of ramping rate towards luminescence and gas sensing characteristics

We report on the effect of the annealing temperature ramping rate on the gas sensing performance towards n-propanol gas and the luminescence properties using p-type NiO gas sensors prepared by the hydrothermal method and annealed at various ramping rates. The crystallite sizes of NiO nanostructures decreased from 22 to 7.4 nm, while the Brunauer–Emmett–Teller measurements complemented that by showing improvement in surface area from 0.15 to 129.11 m2/g. The blue emission observed from photoluminescence studies was associated with oxygen and/or nickel vacancies. The existence of a non-stoichiometric NiO was thoroughly investigated by x-ray photoelectron spectroscopy. Among the fabricated p-type NiO sensors, the ramping rate of 1 °C/min NiO-based sensor demonstrated excellent sensitivity, rapid response/recovery times and low limit of detection to n-propanol in dry air and relative humidity (RH) conditions. Moreover, NiO-1 oC/min-based sensor showed enhanced and stable response in the existence of various RH and its response remained stable with RH percentage. Such stability to RH changes makes it competitive for practical applications. The sensor further showed a clear stability towards n-propanol after 10 days, proving that it can be considered as a possible contender for the detection of n-propanol gas at relatively low operating temperatures.

Morphology tailoring and enhanced electrochemical properties of Cd–Zn co-doped NiO nanorods for high performance supercapacitor

A systematic approach has been introduced to synthesize Cd–Zn co-doped NiO nanostructures with different ratios such as Cd0.07Zn0.03NiO, Cd0.05Zn0.05NiO, Cd0.03Zn0.07NiO and Cd0.01Zn0.09NiO for supercapacitor applications. The XRD studies has confirmed the phase purity with average crystallite size of 40 nm. The SEM characterization has shown that the morphology of nanostructures was tuned from particles to nano-rods structure with increasing the at. % concentration of Zn doping. Optical properties revealed that band gap and recombination rate have strong co-relation with specific capacitance. The CV results have confirmed the pseudocapacitive nature of the as prepared nanostructures and maximum specific capacitance (1485.19 Fg-1) was measured for Cd0.03Zn0.07NiO which is superior than numerous reported values of NiO. The GCD results of Cd0.03Zn0.07NiO performed at 1 A/g scan rate, exhibited excellent charging-discharging ability with high cyclic retention of 82.8%. High capacitance and superior stability of Cd0.03Zn0.07NiO material indicate it as a potential candidate for supercapacitor applications.

Heterojunction formation in In2O3–NiO nanocomposites: Towards high specific capacitance

This study focuses on (In2O3)x(NiO)100-x nanocomposites intended to be used in supercapacitors as electrode materials. Nanocomposites with different ratios of NiO and In2O3 have been synthesized and characterized using XRD, FTIR, TEM and UV–visible spectroscopy. The bandgap energy (Eg) data reveals that the minimum value of Eg in (In2O3)x(NiO)100-x nanocomposites is associated with the formation of p-n heterojunction, for (In2O3)50(NiO)50 nanocomposite, based on its highest electrical resistance, obtained through I–V measurement. The electrochemical measurements depict the pseudocapacitive behaviour of (In2O3)x(NiO)100-x nanocomposites. The CV analysis shows the highest specific capacitance for (In2O3)30(NiO)70 nanocomposite, i.e., 340, 472, 782, 1002, 1381 and 2628 Fg-1 at different scan rates 100, 50, 20, 10, 5 and 1 mVs−1 respectively. Specific discharge capacitance of the same sample is measured as 831, 707, 658 and 449 Fg-1 at 1, 2, 3 and 4 Ag-1 current densities respectively. The strong interaction between closely packed In2O3 and NiO interfaces show the superior specific capacitance in (In2O3)30(NiO)70 nanocomposites compared to neat NiO and In2O3 nanostructure, thus making (In2O3)x(NiO)100-x (x = 30) nanocomposite a suitable candidate for electrode material in electrochemical application.

Highly porous nanostructured NiO@C as interface-effective layer in planar n-i-p perovskite solar cells

Abstract In this study, metal–organic framework (MOF)-derived NiO@C nanoparticles were synthesized and subsequently used as effective interference layers in planar n-i-p perovskite solar cells (PSCs). NiO@C nanoparticles were prepared using MOFs as template, and presented high porosity which improved the conductivity of the photovoltaic device. The morphological and structural characteristics of the NiO@C nanoparticles were examined using X-ray diffraction, Fourier transform infrared, dynamic light scattering, scanning electron microscopy, and Brunauer–Emmett–Teller analyses. Moreover, the photovoltaic properties of the fabricated PSCs were analyzed to elucidate the effect of NiO@C on them. By inserting a NiO@C thin film between the perovskite and spiro-OMeTAD layers of PSCs, the number of defects at the surface of perovskite was reduced and charge transfer was more efficient, which led to the improved power conversion efficiency of the PSCs. The maximum power conversion efficiency of NiO@C-containing PSC was 15.78%, which was higher than that of the control PSC (13.79%).

Improved electrochemical performance of supercapacitors by utilizing ternary Pd-AC-doped NiO nanostructure as an electrode material

Improved electrochemical performance of supercapacitors by utilizing ternary Pd-AC-doped NiO nanostructure as an electrode material

Gas Sensing Properties of Metal Cation Doping Oxide Semiconductors with Hierarchical Nanostructures

Introduction Due to their high sensitivity to the target gases and simplicity in preparation, metal-oxide semiconductors such as SnO2, α-Fe2O3, ZnO, In2O3 and NiO [1-3] have been extensively investigated as sensing materials in the past ten years. Although exciting results have been reported, the development of more highly sensitive and markedly selective gas sensors based on hierarchical oxides nanostructures remains a challenge. In order to meet the increasing demands for making sensors work in more complicated systems and under more harsh conditions, many efforts have been taken such as element doping, heterostructure constructing, and adding catalyst. Among these methods, doping has been reported to be a very simple and feasible way to enhance the gas sensing properties of oxides via altering its structure and grain size or introducing an impurity level and surface defects etc. From this point of view, we adopted metal cations in-situ doping method to adjust the surface NiO nanostructures, aiming to realize the efficient detection of VOCs gases. Method The chemiresistive gas sensor is mainly composed of four parts: 1. A 4 mm long ceramic tube (internal diameter: 0.8 mm, external diameter: 1.2 mm), where a pair of gold electrodes with four Pt wires have been installed originally. 2. Sensing material layer (thickness: ~ 42 um) on the surface of ceramic tube. Taking the material based sensor as an example here. Mix the obtained powder with deionized water to form a slurry and coat the slurry uniformly on the whole surface of the ceramic tube. Then put the well-coated tube in the muffle furnace heating at 500 °C for 3 h in air. 3. A Ni-Cr alloy coil heater, it was inserted through the well-coated and sintered ceramic tube, controlling the working temperature via the flowing current. 4. A hexagon base, which supported the well-coated and sintered ceramic tube through welding. After ageing, the as-prepared sensors were tested through the static test system at a laboratory conditions (20 °C, 10% RH). Results and Conclusions The results indicated that the sensor based on 4.0 at% W-doped NiO sample showed the best gas sensing properties with a ppb-level detection limit (100 ppb), an ultra-high response and a good selectivity to acetone compared to pure NiO. The sensor based on 2.15 at% Al-NiO nanorod-flowers showed the greatly enhanced gas sensing performances to ethanol.

Electrochemical behavior of nanostructured NiO@C anode in a lithium-ion battery using LiNi⅓Co⅓Mn⅓O2 cathode

A NiO@C composite anode is prepared through an alternative synthesis route involving precipitation of a carbon precursor on NiO nanopowder, annealing under argon to form a Ni core, and oxidation at moderate temperature to get metal oxide particles whilst retaining carbon and metallic Ni in traces. The electrode reversibly reacts in lithium cells by the typical conversion process occurring in a wide potential range with the main electrochemical activity at 1.3 V vs. Li+/Li during discharge and at 2.2 V vs. Li+/Li during charge. The NiO@C material exhibits highly improved behavior in a lithium half-cell compared to bare NiO due to faster electrode kinetics and superior stability over electrochemical displacement, leading to a reversible capacity approaching 800 mAh g−1, much enhanced cycle life and promising rate capability. The applicability of the NiO@C anode is further investigated in a lithium-ion NiO@C/LiNi⅓Co⅓Mn⅓O2 cell, which operates at about 2.5 V delivering about 160 mAh g−1 with respect to the cathode mass. The cell exhibits stable response upon 80 cycles at a C/2 rate with coulombic efficiency ranging from 97% to 99%.

A high-sensitivity, fast-response, rapid-recovery UV photodetector based on p-GaN/NiO nanostructures/n-GaN sandwich structure

A high-performance p-GaN/NiO nanostructures/n-GaN ultraviolet (UV) sandwich structure photodetector was fabricated that was composed of NiO nanostructures grown on n-GaN and a p-GaN film layer. The device based on the GaN p-GaN/NiO nanostructures/n-GaN sandwich structure showed a high responsivity and fast response. This study provides a method to fabricate high-response UV photodetectors for GaN-based materials by combining them with metal oxide nanostructures.

Production of nickel oxide nanostructure particles and their photocatalytic degradation of different organic dye

In this study, nickel oxide nanostructured particles were produced by hydrothermal method. X-Ray diffraction (XRD) and transmission electron microscope (TEM) measurements were performed to determine the physical properties of these nanostructured particles. When XRD results are examined, it is seen that NiO nanoparticles are cubic structure. It is understood from the TEM images that these particles are nanostructured. The photocatalytic activities of nanostructured particles were investigated. This examination was carried out by using methylene and methyl blue dyes under the xenon lamp. It has been observed that the photocatalytic degradation rates are high. It was found that the degradation of NiO nanostructured particles on methylene blue was about 59%, the decomposition on methylene blue added H2O2 was about 96% and the degradation on methyl blue was about 92%.

Mesoporous nickel oxide nanostructures: influences of crystalline defects and morphological features on mediator-free electrochemical monosaccharide sensor application

Morphological and surface features are the key tools used to tune the catalytic performance of any metal oxide. In the present study, nickel oxide nanoparticles (NiO NPs) with three different morphologies were prepared using a simple hydrothermal method. The electrocatalytic performance of the prepared NiO NPs was evaluated with regard to the detection of monosaccharide glucose. The physicochemical properties of prepared NiO nanostructures were confirmed using different conventional characterization techniques. The flower-like morphological NiO NPs with nanosized petals have a high surface area and a more defective surface, resulting in improved heterogeneous catalytic activity compared to hexagonal and spherical morphological NiO NPs in glucose oxidation. The anionic and cationic vacancies on the mesoporous surface of NiO nanopetals endorsed an enhanced charge transfer efficiency compared to other NiO morphologies. The effect of scan rate, confirmed by cyclic voltammetry analysis, ensured the diffusion-controlled quasi-reversible electrochemical reaction between surface-modified electrodes and analyte. The NiO petals showed a wide linear detection range (100 nmol L−1–12 mmol L−1) and a lower detection limit of 57 nmol L−1. In addition, the anti-interference ability, repeatability, stability and real sample analysis further affirmed the enhanced catalytic features of NiO nanopetals. The results showed that defective surfaces and surface features of the NiO nanostructures could be used to tune their overall sensor performance in future applications.

The blue luminescence of p-type NiO nanostructured material induced by defects: H2S gas sensing characteristics at a relatively low operating temperature

The detection of hazardous and toxic gases in homes and corporate world, with highly sensitive and selective manner continues to be of great interest. Therefore, we report on the gas sensing characteristics of NiO nanostructures with crystallite sizes of approximately 10–17 nm prepared by a co-precipitation method using various reaction times ranging from 2 to 24 h. The physical variation of the colour from green to black after heat treatment was observed due to non-stoichiometric property of NiO revealing blue emission, which was assigned to oxygen and/or nickel vacancies. The diffuse reflectance spectra revealed a wide direct band gap in the range of 3.4–3.6 eV. The high BET surface area ranging from 46 to 84 m2/g was witnessed. The NiO-8 h sensor revealed an excellent response of 74 towards 60 ppm of H2S at 75 °C in dry air. The detection limit of 0.013 and 1.6 ppm was observed for NiO-8 h based sensor in dry air and RH-40%, respectively. These findings specify that the NiO-8 h sensor has pronounced potential for applications in high-performance H2S gas sensor operating at low temperature. The underlying mechanism for the improved NiO-8 h sensing performance is debated.

Characterization Studies of Nickel Oxide Nanostructure films Prepared by Electrolysis Method for Photo Detectors Applications

Characterization Studies of Nickel Oxide Nanostructure films Prepared by Electrolysis Method for Photo Detectors Applications