NiO Material Research Articles

Incorporation of NiO into SiO2, TiO2, Al2O3, and Na4.2Ca2.8(Si6O18) Matrices: Medium Effect on the Optical Properties and Catalytic Degradation of Methylene Blue.

The medium effect of the optical and catalytic degradation of methylene blue was studied in the NiO/SiO2, NiO/TiO2, NiO/Al2O3, and NiO/Na4.2Ca2.8(Si6O18) composites, which were prepared by a solid-state method. The new composites were characterized by XRD (X-ray diffraction of powder), SEM/EDS, TEM, and HR-TEM. The size of the NiO nanoparticles obtained from the PSP-4-PVP (polyvinylpyrrolidone) precursors inside the different matrices follow the order of SiO2 > TiO2 > Al2O3. However, NiO nanoparticles obtained from the chitosan precursor does not present an effect on the particle size. It was found that the medium effect of the matrices (SiO2, TiO2, Al2O3, and Na4.2Ca2.8(Si6O18)) on the photocatalytic methylene blue degradation, can be described as a specific interaction of the NiO material acting as a semiconductor with the MxOy materials through a possible p-n junction. The highest catalytic activity was found for the TiO2 and glass composites where a favorable p-n junction was formed. The isolating character of Al2O3 and SiO2 and their non-semiconductor behavior preclude this interaction to form a p-n junction, and thus a lower catalytic activity. NiO/SiO2 and NiO/Na4.2Ca2.8(Si6O18) showed a similar photocatalytic behavior. On the other hand, the effect of the matrix on the optical properties for the NiO/SiO2, NiO/TiO2, NiO/Al2O3, and NiO/Na4.2Ca2.8(Si6O18) composites can be described by the different dielectric constants of the SiO2, TiO2, Al2O3, Na4.2Ca2.8(Si6O18) matrices. The maxima absorption of the composites (λmax) exhibit a direct relationship with the dielectric constants, while their semiconductor bandgap (Eg) present an inverse relationship with the dielectric constants. A direct relationship between λmax and Eg was found from these correlations. The effect of the polymer precursor on the particle size can explain some deviations from this relationship, as the correlation between the particle size and absorption is well known. Finally, the NiO/Na4.2Ca2.8(Si6O18) composite was reported in this work for the first time.

Synthesis, characterization and antibacterial activity of a graphene oxide based NiO and starch composite material

This work reports a novel, facile and hydrothermal approach to prepare graphene oxide/NiO/Starch composite materials (GO/NiO/Starch). The composite materials were fully characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray analysis (EDS), X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy and X-ray photo-electron spectroscopy (XPS), and Thermo gravimetric analysis (TGA-DTA). Furthermore, the antibacterial properties of NiO and starch decorated graphene oxide were tested against Staphylococcus aureus by using the well diffusion method. The obtained results show that the GO/NiO/Starch composite material has a substantial antibacterial activity against Staphylococcus aureus.

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.

Eggshell-membrane-templated synthesis of C, S Doped Mesoporous NiO for methanol oxidation in alkaline solution

An interwoven hollow fiber structured mesoporous NiO catalyst doped with C, S was fabricated by the vacuum impregnation and thermal decomposition methods using eggshell membrane as template. The structure of the catalyst was characterized by X-ray diffraction, thermo-gravimetric analysis, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and specific surface area test. Under a high vacuum condition, the synthesized NiO material has a better interwoven fiber and mesoporous structure, which effectively increases the specific surface area of the material. C and S were doped into NiO via eggshell membrane pyrolysis, which then formed C–OH and SO42− species on the surface of the material. The electrocatalytic performance of the catalyst for the oxidation of methanol in alkaline solution was studied by cyclic voltammetry and chronoamperometry. The C, S doped mesoporous NiO material exhibits much higher catalytic efficiency and anti-poisoning ability than that of NiO nanoparticles due to the synergistic catalysis of NiO and doping C–OH and SO42− species.

Synthetic NiO catalyst-assisted peroxymonosulfate for degradation of benzoic acid from aqueous solution.

A heterogeneous NiO catalyst was prepared by a precipitation process using nickel nitrate with oxalic acid and tested for heterogeneous oxidation of benzoic acid (BA) in the presence of peroxymonosulfate (PMS). It was found that the synthetic NiO is highly effective in heterogeneous activation of PMS to produce sulfate radicals ( ) and hydroxyl radicals (· OH), and also presents stable performance in the heterogeneous activation of PMS for BA degradation. Physicochemical properties of the NiO catalyst were characterized by several techniques, such as thermogravimetric analysis, Brunauer-Emmett-Teller, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. It was found that NiO and NiOOH were formed on the synthetic NiO catalyst and were stably distributed on the catalyst surface. Nearly 95% decomposition could be achieved in 30min at the conditions of 500ml 20μM BA solution, 0.25g catalyst, and [PMS]:[BA]=30:1. The heterogeneous reactions, the effects of PMS concentration, and catalyst dosage on the BA degradation were investigated. The heterogeneous BA degradation reactions followed first-order kinetics. Additionally, quenching experiments proved that the dominant radical in the solution was · OH. The experiments results also showed that this approach is effective for the degradation of many other pollutants (such as tetracycline hydrochloride, 2, 4-dichlorophenol, Acid orange 7, rhodamine B, and methyl red). PRACTITIONER POINTS: A novel NiO material was fabricated for degradation of benzoic acid. The synthetic NiO catalyst comprised active NiO and NiOOH. The main radical for benzoic acid removal rate was · OH. A plausible mechanism for catalyzed degradation of the benzoic acid was proposed.

Structural and optical properties of nickel oxide nanoparticles: Investigation of antimicrobial applications

The green synthesis of nickel oxide nanoparticles were prepared by microwave combustion method. The prepared NiO material was annealed at 200°C & 700°C. The XRD pattern confirms the very good crystallinity of the material and the average crystallite size was found to be 20 nm and 30 nm respectively for both NiO samples. However, the morphology of samples were studied using SEM analysis and shows spherical shape with agglomeration matrix. In particular, the SEM images of prepared NiO nanoparticles were dried at 200 °C and annealed at 700 °C which gives the average particle size of 19 nm and 30 nm. Moreover, FTIR study was carried out to identify the functional group present in prepared samples extensively. In that view, the UV–vis absorption spectra of bandgap values are calculated. Likewise, EDX pattern were shown the composition element present in the compound. The antibacterial study reveals that both the samples shows good antibacterial activity on both gram positive and gram-negative bacteria's. Hence, this green synthesized NiO material can be used for antibacterial applications.

Understanding photocatalytic activity and mechanism of nickel-modified niobium mesoporous nanomaterials

To better understand the photocatalysis oxidation mechanism of different types of coupled semiconductors, mesoporous niobium(V) oxides (n-type) with relatively high surface areas (140 m2 g−1) were synthesized by Evaporation Induced Self-Assemble method and modified with different amounts of NiO (p-type). The materials are polycrystalline nanostructures, with mesoporous of approximately 12 nm and bandgap values in the UVA range of the spectrum (344–356 nm). The materials showed remarkable photocatalytic activity and the addition of nickel oxide increased the reducibility of the Nb5+ species and improved the charge transfer in the materials. Studies with indigo carmine dye have shown that the niobium-based materials are able to decolorize a 40 ppm solution in 20 and 60 min (1.0% NiO material) in photo-Fenton like reaction, and photocatalysis reactions, respectively, without the strong adsorption of the molecule to the material surface. In addition, in the presence of a radical scavenger the photocatalytic reactions half-life time showed an increase of up to 11 times, which indicates that the indirect oxidation mechanism, with the formation of radicals, is predominant. The formation of hydroxyl radicals during irradiation was confirmed by EPR analysis with the spin trapping method.

Highly Selective, ppb-Level Xylene Gas Detection by Sn2+-Doped NiO Flower-Like Microspheres Prepared by a One-Step Hydrothermal Method

Detecting xylene gas is an important means of avoiding human harm from gas poisoning. A precise measurement demands that the gas sensor used must have high sensitivity, high selectivity, and low working temperature. To meet these requirements, in this study, Sn2+-doped NiO flower-like microspheres (SNM) with different amounts of Sn2+ synthesized by a one-step hydrothermal process were investigated. The responses of gas sensors based on different Sn2+-doped NiO materials for various targeting gases were fully characterized. It was found that all of the synthesized materials exhibited the best gas response at a working temperature of 180 degrees, which was much lower than the previously reported working temperature range of 300–500 degrees. When exposed to 10 ppm xylene, the 8 at% Sn2+-doped NiO sensor (mol ratio) exhibited the highest response, with a value of 30 (Rg/Ra). More significantly, the detection limit of the 8 at% Sn2+-doped NiO sensor for xylene is down in the ppb level. The Sn2+-doped NiO material also exhibits excellent selectivity for other gases with long-term stability and repeatability. The significant improvement in the response to xylene can theoretically be attributed to a decrease in the intrinsic hole carrier concentration, higher amounts of adsorbed oxygen and active sites.

NiO and Ag@NiO Nanomaterials for Enhanced Photocatalytic and Photoluminescence Studies: Green Synthesis Using Lycopodium Linn.

NiO and Ag-NiO nano particles were prepared using Lycopodium extract as a fuel via solution combustion synthesis (SCS) at 500 ºC. From the PXRD, FTIR, UV-DRS studies the synthesized NPs were characterized. The morphologies of the prepared NPs were studied by SEM and TEM analysis. The synthesized NPs were tested for photocatalytic and photoluminescence studies. The PXRD data indicated that the synthesized nanoparticles belong to cubic phase structure and space group Fm-3m. The FTIR spectrum of NiO exhibited the absorption bond at 427 cm-1 is associated to Ni-O vibration band. The SEM data revealed that agglomeration was obtained. NiO and Ag-NiO Nps were taken for determine the photocatalytic activity study on methylene blue dye, the results indicated that Ag-NiO NPs exhibited promising photocatalytic activity. This is due to occurrence of Ag particles on the NiO material, which makes the catalyst more sensitive. Furthermore, a photoluminescence study for NiO and Ag-NiO was studied.

Adsorption Dynamics of Redox Active Species onto Polarized Surfaces of Sensitized NiO.

Mesoporous NiO films were deposited by means of a screen printing technique onto fluorine-doped tin oxide transparent electrodes and consequently sensitized with Erythrosin B (EryB) dye. The obtained colored NiO material was used as a working electrode in a three-electrode cell to study the evolution of the triple semiconductor/dye/electrolyte interface upon electrochemical polarization in dark conditions. The electrolyte was a solution of I3–/I– in acetonitrile, with the redox couple representing the typical redox shuttle of dye-sensitized solar cells (DSCs). The adopted electrochemical conditions were devised in order to simulate the actual electrical environment of the NiO/dye photocathode in a light-soaked DSC. The use of a benchmark sensitizer EryB and of the most widely used redox mediator I3–/I– is particularly meaningful for the study of the adsorption dynamics and the determination of possible degradative phenomena on the basis of the behavior of numerous analogue systems. Therefore, for the first time, the evolution of the NiO/EryB/I3–/I– multiple interface was investigated combining the electrochemical characterization with ex situ spectroscopic analysis by means of X-ray photoelectron spectroscopy. The resulting picture shows that EryB in the immobilized state promotes the redox processes based on the I3–/I– couple. Moreover, the EryB sensitizer inhibits the phenomena of recombination between the metal oxide semiconductor and the redox couple.

Hierarchically constructed NiO with improved performance for catalytic transfer hydrogenation of biomass-derived aldehydes

A 3D nanometer-scaled NiO material with urchin-like structure was prepared via a facile route, and served as a highly efficient and durable catalyst for catalytic transfer hydrogenation of bio-based furfural to furfuryl alcohol using 2-propanol as H-donor and solvent.

Enhanced electrochemical glucose-sensing properties of NiO nanospheres modified with indium

In this work, a binder-free and environmentally benign method is developed to synthesize indium-doped nickel oxide material on nickel foam at room temperature for glucose detection. Through SEM and XPS measurement, we prove the successful doping of indium ions into the crystal lattice of nickel oxide and reveal the transformation of the nickel oxide material after doped. With the help of more absorbed state oxygen, this material exhibits unique advantages for the oxidation of glucose. As a result, the sensitivity of this material reaches 57000 µA µM−1 cm−2 and the limit of detection on glucose is 0.02 µmol L−1. The improved sensing performance of the nickel oxide material indicates the effective influence of indium ions in NiO material and advances our understanding of non-enzymatic electrochemical glucose sensors.

Magnetic behavior of nanostructured NiTiO3 and NiO material: Anomalous increase in coercivity

In this paper we present an interesting magnetic property of ilmenite NiTiO3 material prepared by sol-gel mediated slow evaporation induced self-assembly (EISA) method using Pluronic F127. Two oxide samples were prepared using Ni:Ti 1:1 and 1:2M ratios under similar reaction conditions. It is observed from powder XRD analysis that sample NTO11 (Ni:Ti=1:1) is a predominating NiTiO3 phase with small percentage of NiO and TiO2, whereas NTO12 (Ni:Ti=1:2) is a mixture of anatase TiO2 and NiO structures. Both materials reveal, presence of exchange bias (in hysteretic M-H loop) decreasing with increase in temperature. Both samples show an anomalous increase of magnetic coercivity with increase in temperature. The anomalous coercivity increase in NTO11 is much more pronounced than in NTO12 (by a factor of 6). We explain this large anomaly in NTO11, by invoking layer structure and weak interlayer exchange coupling between Ni moments in NiTiO3, which allows a transition near the surface of nanoparticles from antiferromagnetically coupled ferromagnetic planes of Ni moments to uncoupled set of ferromagnetic layers on the surface (each layer can be thought of as single ferromagnetic plane), blocked along different directions. The increased coercivity at higher temperature is due to excess coercivity of the nanosized ferromagnetic layers.

Synthesis and Research of Egg shell-yolk NiO/C porous composites as Lithium-ion Battery Anode Material

An egg shell-yolk NiO/C porous composite has been prepared as lithium-ion battery anode material by two-pot hydrothermal method. Thermogravimetry(TG), X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), Raman spectroscopy, and nitrogen isothermal adsorption-desorption have been used to study the microstructure of the material. LANHE cell tester and electrochemical workstations are used to investigate electrochemical performance. Results show that amorphous carbons exist in porous NiO/C, which possesses an internal loose spherical structure. The discharge capacity for the 100th cycle is maintained at 625.3mAh/g, and the capacity retention ratio is 94.1% relative to the 2nd discharge capacity. The composite has a unique egg shell-yolk porous structure, which buffers the volume change and prevents the aggregation of active NiO material during cycling to enhance material performance. When the current density is increased to 800mA/g, the capacity stabilizes at 400.1mAh/g, reflecting an outstanding rate performance.

Porous nickel oxide pseudo-capacitive materials fabricated by Ni-Schiff base nanostructures template

Three nanoscale Ni-Schiff-base coordination polymer particles have been firstly prepared in poor solvent (DMF) through a precipitation method. XRD, TGA and EA results show that as-synthesized compounds are either amorphous or crystalline. High temperature annealing of these Ni-based compounds can result in pseudo-capacitive NiO electrodes. Series of electrochemical measurements illustrated that the as-prepared NiO material, especially for NiO nanospheres could deliver a maximum specific capacitance of 153Fg−1 and good stability over 1000 cycles with the capacitance retention of 100%, indicating the morphology and resistance effect on the diffusion-controlled redox reaction between the OH− ions and the NiO samples.

Hydrothermally grown Ni0.7Zn0.3O directly on carbon fiber paper substrate as an electrode material for energy storage applications

Nickel oxides because of their excellent electrochemical performance have been considered attractive materials for electrochemical energy storage. However, their application as active material for redox supercapacitor electrodes has been limited by poor electrical conductivity. In order to improve this property, herein we synthesized a nanonet of NiZn-mixed oxide, by facile hydrothermal route, directly on the substrate. The Zn-modified oxide material showed good electrochemical performance, displaying specific capacitance of 770 F g−1 at 1 A g−1 and almost 120% capacitance retention after 2000 cycles of charge discharge at 2 A g−1 in 2 M KOH. Electrochemical impedance results revealed that the Ni0.7Zn0.3O mixed oxide displayed increased conductivity compared to the single NiO material.

Template-free synthesis of mesoporous nickel oxide electrode material with three-dimensional flowerlike morphology

In this work, mesoporous NiO with three-dimensional flowerlike morphology were synthesized from precursor α-Ni(OH)2 by a facile template-free modified homogeneous precipitation method, where CO(NH2)2 could be acted as a chelating agent at lower temperatures, and source material of OH− utilizing the hydrolysis reaction at high temperatures. The structures of the NiO materials were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. The specific surface area of NiO was 140m2g−1, which was about 86% of the specific surface of precursor α-Ni(OH)2 (163m2g−1). The pore diameter of NiO and α-Ni(OH)2 were approximately 3.6nm and 1.7nm, corresponding to mesoporous and microporous, respectively. The NiO material used as an electrode in 6molL−1 KOH electrolyte exhibited a specific capacitance of 289Fg−1 at a current density of 5Ag−1, and could still retain 262Fg−1 at 10Ag−1 and 257Fg−1 at 20Ag−1, respectively. In addition, almost no decrease of the capacitance was observed after 4000th charge-discharge cycles at a current density of 10Ag−1.

Synthesis of hierarchical NiO microsphere with waxberry-like structure and its enhanced lithium storage performance

This work reports a facile synthesis of hierarchical NiO microspheres with a waxberry-like structure by one-pot hydrothermal reaction followed by thermal annealing. We detected the composition of precursor by using two-dimensional detector X-ray diffractometer (XRD2). In addition, XRD, TG, SEM, TEM and BET measurement were used to characterize the structural properties of the as-prepared materials. The XRD result showed that the precursor has been completely transformed into NiO materials by calcination at 300 °C (denoted as NiO-300). Moreover, thanks to the well conservation of hierarchical structure consisting of needle-like nanoparticles in NiO-300 sample, the charge capacity can be stabilized at 597.8 mAh g−1 reversibly when cycled 100 times at a relatively high current density of 0.7C which show a very competitive capacity compared with other nano-structure NiO materials and commercial NiO material. It also showed high rate capability, the reversible charge capacity is still retained to 370.3 mAh g−1, even for the condition of 4.46C (high rate). This NiO-300 material's superior electrochemical performance should be exclusively attributed to the well conserved hierarchical waxberry-like structures, which shortens the diffusion pathways of lithium ions and electrons transfer as well as accommodate the drastic volume change during electrochemical charge/discharge process.

Dye-sensitized PS-b-P2VP-templated nickel oxide films for photoelectrochemical applications.

Moving from homogeneous water-splitting photocatalytic systems to photoelectrochemical devices requires the preparation and evaluation of novel p-type transparent conductive photoelectrode substrates. We report here on the sensitization of polystyrene-block-poly-(2-vinylpyridine) (PS-b-P2VP) diblock copolymer-templated NiO films with an organic push-pull dye. The potential of these new templated NiO film preparations for photoelectrochemical applications is compared with NiO material templated by F108 triblock copolymers. We conclude that NiO films are promising materials for the construction of dye-sensitized photocathodes to be inserted into photoelectrochemical (PEC) cells. However, a combined effort at the interface between materials science and molecular chemistry, ideally funded within a Global Artificial Photosynthesis Project, is still needed to improve the overall performance of the photoelectrodes and progress towards economically viable PEC devices.

A highly efficient non-enzymatic glucose biosensor based on a nanostructured NiTiO3/NiO material

NiTiO3/NiO self-assembled crystalline nanoparticles synthesized via a surfactant-assisted EISA method exhibit excellent sensitivity and selectivity towards glucose biosensing with a very low limit of detection.