Nickel Oxide Materials Research Articles

Physicochemical and supercapacitive properties of electroplated nickel oxide electrode: effect of solution molarity

With an aim of physicochemical characteristics and electrochemical supercapacitor studies with X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDAX) technique, X-ray photoelectron spectroscopy (XPS) and surface wettability, nickel oxide (NiO) thin films of different molarities i.e. (0.1, 0.2, 0.3 and 0.4 M) have been synthesized onto stainless-steel substrate using potentiostatic mode of electrochemical method. The XRD result confirms crystalline nature with cubic crystal structure of the NiO. The SEM micrographs reveal homogenous and smooth surfaces. Existence of Ni and O in EDAX spectrums of all samples supports the formation of NiO. Expected peaks are confirmed from XPS surface analyses. Contact angle measurement of 0.1, 0.2 M film showed hydrophilic, however 0.3, 0.4 M film showed hydrophobic in character. The optimal potential for potentiostatic mode of electrochemical method of NiO is 1.8 V. The electrochemical properties of the NiO electrodes are studied in detail by cyclic voltammogram, galvanostatic charge–discharge and electrochemical impedance spectroscopy measurements. The specific capacitance of the NiO electrode is 667.24 Fg−1 in Na2SO4 electrolyte of 1 mol/L. The achieved specific energy, power and coulombic efficiency of NiO electrode were 2.55 Whkg−1, 6.23 kWkg−1 and 92.86% respectively. Moreover, the NiO electrode shows excellent cyclic performance after 1000 cycles. An effective and convenient technique has been developed to produce nickel oxide material promising for designing of innovative capacitors.

Ultra High Electrical Performance of Nano Nickel Oxide and Polyaniline Composite Materials.

The cooperative effects between the PANI (polyaniline)/nano-NiO (nano nickel oxide) composite electrode material and redox electrolytes (potassium iodide, KI) for supercapacitor applications was firstly discussed in this article, providing a novel method to prepare nano-NiO by using β-cyelodextrin (β-CD) as the template agent. The experimental results revealed that the composite electrode processed a high specific capacitance (2122.75 F·g−1 at 0.1 A·g−1 in 0.05 M KI electrolyte solution), superior energy density (64.05 Wh·kg−1 at 0.2 A·g−1 in the two-electrode system) and excellent cycle performance (86% capacitance retention after 1000 cycles at 1.5 A·g−1). All those ultra-high electrical performances owe to the KI active material in the electrolyte and the PANI coated nano-NiO structure.

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.

Preparation and characterization of Li0.30Cr0.10Ni0.60O/polyvinylidene fluoride composites with high dielectric constants

Abstract Lithium chromium nickel oxide (Li 0.30 Cr 0.10 Ni 0.60 O, LCNO) materials were prepared by sol-gel process and calcined at the temperature of 1000 °C for 3 h. Mechanical mixing process and hot pressing fabricated the composites between LCNO and polyvinylidene fluoride (PVDF). Effects of the amount of LCNO filler on the structure and dielectric properties of LCNO/PVDF composites were investigated. The LCNO/PVDF composites were characterized by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Furthermore, the dielectric properties of the LCNO/PVDF composites were also investigated. From TGA results, the decomposition step of LCNO/PVDF composites depends on the LCNO content and weight loss decrease with increasing LCNO contents due to the presence of LCNO in PVDF. All LCNO/PVDF composites exhibited two-phase structures of cubic rock-salt NiO structure and α-, γ- phases of PVDF. It is revealed that dielectric constant of the polymer composite increases with increasing LCNO content. This might be due to the formation of micro-capacitor network. The LCNO/PVDF composite with amount of 30 wt% showed the best properties with a high dielectric constant of 59.27 and low loss tangent of 0.31 at the frequency of 1 kHz and at room temperature. The composite gave a high dielectric constant, which was 2.82 times higher than that of pure PVDF. Therefore, the flexible high dielectric constant and low loss tangent of the composite were weakly frequency dependent, which might be suitable for capacitor applications.

Fabrication and Super Capacitive Performance of Nanoporous Nickel Oxide Film

AbstractIn order to improve the whole performance of a single kinds of materials, the nanoporous nickel (NPN) oxide film was fabricated by the method of interfacial electroless plating. The nickel (Ni) was deposited on the surface of the substrate in three dimensional nanoporous structure, and then the surface layer of Ni is converted into nickel oxide (NiO) after exposure to oxygen in the air. The as‐prepared nickel oxide material not only maintains the porous structure of the substrate, but also increases the specific surface area of the material and improves the conductivity, thereby significantly improving the electrochemical capacitance performance of the material which characterized by X‐ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X‐ray spectrometer (EDS). The mass specific capacitance is 387 F g−1 and volumetric specific capacitance is 964 F cm−3. Therefore, the porous nickel oxide film is an electrode material with great potential for super capacitors.

Silicone Nanofilament-Supported Mixed Nickel-Metal Oxides for Alkaline Water Electrolysis

Mixed transition metal nickel oxide materials (M-NiO; M = Co, Mn, Fe) supported on silicone nanofilaments (SNFs) were synthesized via precipitation reaction with urea. All materials were evaluated for their OER activity in 0.1 M KOH, of which the Fe-NiO/SNFs showed a notable improvement over NiO/SNFs and unsupported NiO. The results presented herein demonstrate the extension of our previously reported synthesis for NiO/SNFs to yield SNF-supported mixed transition metal-oxide materials. The versatility and scalability of the synthesis are particularly interesting for the facile preparation of three-dimensional, binderless electrodes for alkaline water electrolysis applications.

The Influence of a Nickel Precursor on the Synthesis of Nanosized NiO Material Using the Hydrothermal Method: Characterization and Electrocatalytic Oxidation of Methanol

Nickel oxide (NiO) was prepared by the hydrothermal method using hydrogen peroxide to form a nickel peroxide complex, and irregular spherical and rod-shaped NiO nanoparticles were obtained. The factors that influence the physical properties of NiO nanoparticles were studied using scanning electron microscopy (SEM), isothermal gas adsorption/desorption by Brunauer, Emmett and Teller (BET), and X-ray diffraction (XRD) techniques. This study found that the precursor salt chosen (nickel acetate or nickel nitrate) significantly affected the shape, particle size, and surface area of the synthesized nanosized NiO powders. The ratio of hydrogen peroxide (H2O2) to nickel nitrate or acetate and the heating rate of calcinations were also important in determining the physical properties of the nanosized NiO. The unmodified PAni electrode shows no activity for the methanol oxidation reaction in 0.1 M NaOH. However, the nickel-modified PAni electrode is a good catalyst for this reaction and high current densities can be reached. The height of the oxidation peak of methanol increases by increasing the alcohol concentration. The results indicate that the reaction of the electro-oxidation of methanol is an activation-controlled proceeding by a direct chemical reaction with NiO(OH) for thin nickel oxides and by charge transfer with the electrode for thick oxides.

Preparation of high surface area mesoporous nickel oxides and catalytic oxidation of toluene and formaldehyde

Mesoporous nickel oxide (NiO) nanoparticles were synthesized by the thermal decomposition reaction of Ni(NO3)2·9H2O using oxalic acid dihydrate as the mesoporous template reagent. The pore structure of nanocrystals could be controlled by the precursor to oxalic acid dihydrate molar ratio, thermal decomposition temperature and thermal decomposition time. The structural characteristic and textural properties of resultant nickel oxide nanocrytals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 adsorption–desorption isotherm and temperature programmed reduction. The results showed that the most excellently mesoporous nickel oxide particles (m-Ni-1-4) with developed wormlike pores were prepared under the conditions of the mixed equimolar precursor and oxalic acid and calcined for 4 h at 400 °C. The specific surface area and pore volume of m-Ni-1-4 are 236 m2 g−1 and 0.42 cm3 g−1, respectively. Over m-Ni-1-4 at space velocity = 20,000 mL g−1 h−1, the conversions of toluene and formaldehyde achieved 90 % at 242 and 160 °C, respectively. It is concluded that the reactant thermal decomposition with oxalic acid assist is a key step to improve the mesoporous quality of the nickel oxide materials, the developed mesoporous architecture, high surface area, low temperature reducibility and coexistence of multiple oxidation state nickel species for the excellent catalytic performance of m-Ni-1-4.

Optically transparent and electrically conductive NiO window layer for Si solar cells

Nickel oxide (NiO) material has been functionally applied for Si solar cells. Optically transparent and electrically conductive NiO was used as a window layer for Si solar cells to provide a relatively high efficiency of 15.37%. An optically transparent NiO layer was coated onto Si by large-area applicable sputtering deposition to give good crystalline structure. NiO-coating on Si spontaneously reduces the light reflection for visible range light, resulting in the improved current profiles. Due to the electrically low sheet resistance, the NiO-coating design is effective to improve the open circuit voltage and fill factor of solar cells. The optical and electrical benefits of NiO would provide a route of improvement for various photoelectric devices, including solar cells.

Physicochemical identity and charge storage properties of battery-type nickel oxide material and its composites with activated carbon

The structural properties of annealed nickel oxide and its composites with activated carbon (synthesized via simple precipitation methods) have been addressed using X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption/desorption method and scanning electron microscopy. The charge storage properties of materials have also been investigated in three- and two-electrode configurations by means of cyclic voltammetry and galvanostatic charging/discharging in alkaline media. The results are consistent with the view that, depending on a method of preparation, the resulting nickel oxide films may exhibit redox characteristics different from that typically observed for nickel oxide-based materials. It is demonstrated that faradaic-type (redox) reactions, that are typical for battery-like materials, contribute predominantly to the high electrode capacity of 257Cg−1 (at 0.1Ag−1). By combining nickel oxide with a capacitive material such as activated carbon within the two-electrode symmetric cell, systems with increased charge-storage capabilities have been obtained. The fact, that the voltage window of nickel oxide-based cell has been broadened positively from 0.6V to 1V upon introduction of activated carbon, has also resulted in the increase of the cell’s energy and power densities as well.

3-D periodic mesoporous nickel oxide for nonenzymatic uric acid sensors with improved sensitivity

3-D periodic mesoporous nickel oxide (NiO) particles with crystalline walls have been synthesized through the microwave-assisted hard template route toward the KIT-6 silica. It was investigated as a nonenzymatic amperometric sensor for the detection of uric acid. 3-D periodic nickel oxide matrix has been obtained by the hard template route from the KIT-6 silica template. The crystalline nickel oxide belonged to the Ia3d space group, and its structure was characterized by X-ray diffraction (XRD), N2 adsorption–desorption, and transmission electron microscopy (TEM). The analysis results showed that the microwave-assisted mesoporous NiO materials were more appropriate to be electrochemical sensors than the traditional mesoporous NiO. Cyclic voltammetry (CV) revealed that 3-D periodic NiO exhibited a direct electrocatalytic activity for the oxidation of uric acid in sodium hydroxide solution. The enzyme-less amperometric sensor used in the detection of uric acid with detection limit of 0.005μM (S/N=3) over wide linear detection ranges up to 0.374mM and with a high sensitivity of 756.26μAmM−1cm−2, and a possible mechanism was also given in the paper.

Enhanced Gas-Sensing Performance of Fe-Doped Ordered Mesoporous NiO with Long-Range Periodicity

This paper reports the effect of mesoporous morphology and metal doping on the gas-sensing behavior of ordered mesoporous nickel oxide (NiO) materials. NiO samples with varied porous periodicity have been successfully synthesized via an improved nanocasting method. TEM, SEM, SAXRD, XRD, and nitrogen physisorption techniques are used to prove the presence of different mesostructured periodicity, as well as crystallinity, particle size, and pore size distribution of the as-synthesized NiO. The gas-sensing characterization indicates that the ordered mesoporous NiO with a long-range mesoporous periodicity based gas sensor exhibits a better ethanol sensing property than that of the ordered mesoporous NiO with short-range mesoporous periodicity. This result is due to the large specific surface area with sufficient sensing active sites, appropriate pore size distribution for enough gas diffusion, and proper particle size for effective charge accumulation of ordered mesoporous NiO with long-range periodicity. Fur...

Electrochromic performance of nanocomposite nickel oxide counter electrodes containing lithium and zirconium

Nickel oxide materials are suitable for counter electrodes in complementary electrochromic devices. The state-of-the-art nickel oxide counter electrode materials are typically prepared with multiple additives to enhance peformance. Herein, nanocomposite nickel oxide counter electrodes were fabricated via RF magnetron co-sputtering from Ni–Zr alloy and Li2O ceramic targets. The as-deposited nanocomposite counter electrodes were characterized with inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). It was found that the stoichiometry, crystal structure and electronic structure of the nickel oxide-based materials could be readily tuned by varying the Li2O sputter deposition power level. Comprehensive electrochromic evaluation demonstrated that the performance of the nickel oxide-based materials was dependent on the overall Li stoichiometry. Overall, the nanocomposite nickel oxide counter electrode containing lithium and zirconium synthesized with a Li2O deposition power of 45W exhibited the optimal performance with an optical modulation of 71% and coloration efficiency of 30cm2/C at 670nm in Li-ion electrolyte.

Origin of Electrochromism in High-Performing Nanocomposite Nickel Oxide

Electrochromic effects of transition metal oxides provide a great platform for studying lithium intercalation chemistry in solids. Herein, we report on an electronically modified nanocomposite nickel oxide (i.e., Li2.34NiZr0.28Ox) that exhibits significantly improved electrochromic performance relative to the state-of-the-art inorganic electrochromic metal oxides in terms of charge/discharge kinetics, bleached-state transparency, and optical modulation. The knowledge obtained from O K-edge X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) suggests that the internally grown lithium peroxide (i.e., Li2O2) species plays a major role in facilitating charge transfer thus enabling optimal electrochromic performance. This understanding is relevant to recent theoretical studies concerning conductivity in Li2O2 for lithium-air batteries (as cited in the main text). Furthermore, we elucidate the electrochromism in modified nickel oxide in lithium ion electrolyte with the aid of Ni K-edge XAS and Ni L-edge XAS studies. The electrochromism in the nickel oxide materials arises from the reversible formation of hole states on the NiO6 units, which then impacts the Ni oxidation state through the Ni3d-O2p hybridization states. This study sheds light on the lithium intercalation chemistry for general energy storage and semiconductor applications.

Hole Doping in Al-Containing Nickel Oxide Materials To Improve Electrochromic Performance

Electrochromic materials exhibit switchable optical properties that can find applications in various fields, including smart windows, nonemissive displays, and semiconductors. High-performing nickel oxide electrochromic materials have been realized by controlling the material composition and tuning the nanostructural morphology. Post-treatment techniques could represent efficient and cost-effective approaches for performance enhancement. Herein, we report on a post-processing ozone technique that improves the electrochromic performance of an aluminum-containing nickel oxide material in lithium-ion electrolytes. The resulting materials were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy, and X-ray absorption spectroscopy (XAS). It was observed that ozone exposure increased the Ni oxidation state by introducing hole states in the NiO(6) octahedral unit. In addition, ozone exposure gives rise to higher-performing aluminum-containing nickel oxide films, relative to nickel oxide containing both Al and Li, in terms of switching kinetics, bleached-state transparency, and optical modulation. The improved performance is attributed to the decreased crystallinity and increased nickel oxidation state in aluminum-containing nickel oxide electrochromic films. The present study provides an alternative route to improve electrochromic performance for nickel oxide materials.

Mesoporous NiO ultrathin nanowire networks topotactically transformed from α-Ni(OH)2 hierarchical microspheres and their superior electrochemical capacitance properties and excellent capability for water treatment

Low-cost controlled strategies for the synthesis of mesoporous nickel oxide materials are highly desirable owing to its significant applications for power storage and other fields. In this contribution, we develop a novel hydrothermal route to synthesize α-Ni(OH)2, in which urea has not only been utilized to produce hydroxyl anions, but also to organize ultrathin nanowires/nanosheets into a network-like hierarchical assemblage. The morphological evolution process of this organized product has been investigated by examining different reaction intermediates during the synthesis. The growth and thus final assemblage of α-Ni(OH)2 can be finely tuned by selecting preparative parameters such as the molar ratio of starting chemicals. Based on the topotactic transformation from α-Ni(OH)2, various mesoporous NiO hierarchical microspheres from ultrathin nanowires/nanosheets self-assembly have been prepared via thermal decomposition in an air atmosphere. The electrochemical performances of the typical nickel oxide products are evaluated. It is demonstrated that tuning of the surface texture and the pore size of the NiO products is very significant for electrochemical capacitor and water treatment applications. The mesoporous NiO network-like hierarchical microspheres exhibit excellent cyclic performance with nearly 100% capacity retention at a current density of 10 A g−1 in a testing range of 2000 cycles. Moreover, the mesoporous NiO network-like hierarchical microspheres have excellent ability to remove organic pollutants from wastewater by their wonderful surface adsorption ability.

Preparation for Nano-NiO by Electrolysis of Nickel in HOCH2CH2OH Solution

A method to prepare nickel oxide material which has a high purity and nano-sized particle was developed. nano NiO was synthesized by sol-gel method using nickel alkoxide as precursors. The structural characterization of the obtained materials was performed by thermal analysis TG-DTA, X-ray diffraction (XRD), Laser Raman spectra and Transmission Electron Microscopy (TEM). The characterization results indicated that NiO nano-particles (size 25–35 nm) are obtained by hydrolyzing of metal alkoxide of Ni(OCH2CH2OH)2 and possess high purity.

Controllable preparation of NiO macrotubes from NiC2O4 and its application in supercapacitors

In this article, the tube-like nickel oxide materials was synthesized by decomposition of nickel oxalate which was prepared by a facile hydrothermal method. Some experimental parameters affecting the morphology were studied. The electrochemical capacitive properties of the nickel oxide macrotubes were investigated using cycling voltammetry and charge/discharge techniques with KOH as electrolytes. The specific capacitance of the obtained nickel oxide macrotube electrode was measured to be as high as 701.2 F g−1 at a current density of 0.5 A g−1. The effect of calcination temperature and current density on the specific capacities were also studied. Furthermore, the obtained nickel oxide shows a good capacitive retention of ca. 93% after 1000 charge/discharge cycles.

High surface area alumina-supported nickel (II) oxide aerogels using epoxide addition method

Nickel (II) oxide aerogels with an amorphous alumina support were synthesized by the expoxide addition method. The monoliths were obtained by adding propylene oxide to an alcoholic solution of hydrated metal nitrate salts. The wet gels were dried by supercritical extraction to produce porous monolithic aerogels. The as-synthesized aerogels were amorphous containing aluminum and nickel hydroxides. Annealing of the as-synthesized aerogels at 400 °C yields crystalline nickel oxide materials which retain the high surface areas (>160 m2/g) and porosities of the original aerogels. The resultant aerogel materials were characterized using powder X-ray diffraction, thermo-gravimetric analysis, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, and nitrogen adsorption/desorption analysis.

Fast-Switching Electrochromic Li + -Doped NiO Films by Ultrasonic Spray Deposition

A low cost, high throughput deposition method for films of nickel oxide (NiO) and lithium-doped nickel oxide with improved electrochromic performance is demonstrated. This method is based on ultrasonic spray deposition of aqueous-based precursor solutions in air at atmospheric pressure, which represents a significant cost savings compared to vacuum deposition methods. The resultant materials are characterized by X-ray diffraction, Raman spectroscopy, electron microscopy, and electrochemical measurements. Electrochromic performance is demonstrated with in situ optical transmission measurements during electrochemical characterization. Nickel oxide materials color anodically and are thereby ideally suited to be used as counter electrode for the well-known tungsten oxide system in “smart” window applications. The coloration of nickel oxide materials is known to be slow when compared to and thereby limits the overall response time of a tandem device. The analysis of potential step response data shows that our lithium-doped nickel oxide material achieves 90% of its total coloration change in , which is comparable to reported measurements for . These results significantly mitigate a potential bottleneck to the adoption of metal oxide electrochromic windows not only by demonstrating similar performance between NiO and , but by achieving this result via low cost, highly scalable processing methods.