Pure Nickel Oxide Nanoparticles Research Articles

Effect of precursor concentration on structural and optical properties of nickel oxide nanoparticles synthesized by facile sol-gel method

We report a simple, fast and efficient sol-gel technique to synthesize nickel oxide (NiO) nanoparticles of variable sizes. For this, three different precursor concentrations, viz. 0.1, 0.3, and 0.5 M were used. All the samples were maintained at a pH of 8 and calcined at 500 °C for 4 h. Our study shows the formation of well-crystalline, spherical, single-phase, pure NiO nanoparticles. The size of the nanoparticles increases with the concentration of the precursor solution. All nanoparticles show absorption peaks at the wavelength of ∼358 nm, which lie in the UV region and a near band edge emission peak at ∼390 nm.

Chemical Synthesis and Antipseudomonal Activity of Al-Doped NiO Nanoparticles

Synthesis of efficient antibacterial agents has become extremely important due to the emergence of antibiotic resistant bacteria. This is especially true for Pseudomonas aeruginosa, an opportunistic pathogen having ability to rapidly develop resistance to multiple classes of antibiotics thus limiting the efficacy of antibiotics approved for clinical use. Aluminum (Al)-doped NiO nanoparticles are of special interest due to their enhanced antipseudomonal properties at certain Al-doping levels. The composite hydroxide mediated (CHM) approach was opted for the synthesis of pure nickel oxide (NiO) and Al-doped nickel oxide (Ni1–xAlxO; x = 5, 10, 15, 20, 25, and 30 wt.%) nanoparticles. X-ray diffraction (XRD) technique was used for structural analysis of these nanoparticles. Morphology and elemental composition of these nanoparticles were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy, respectively. The optical properties were investigated by using UV-visible spectroscopy and Kubelka-Munk Theory and Tauc relation were employed for energy bandgap calculation of these nanoparticles. The antibacterial activity of representative Al-doped NiO nanoparticles was assessed on multidrug-resistant clinical P. aeruginosa strains. The agar well and disc-diffusion methods were used to assess the antibacterial efficacy of (Al)-doped NiO compared to pure NiO nanoparticles. Interestingly, a gradual increase in the antibacterial activity was observed with increasing Al-doping concentration and the highest antibacterial activity was observed at x = 15 wt.% Al-doping concentration. The antipseudomonal efficacy of Ni1–xAlxO nanoparticles was comparable to aztreonam antibiotic, primarily used for Gram-negative bacterial infections. Hence, it is proposed that these nanoparticles can be used for coating surgical devices, bone prostheses, medical implants, antibacterial clothing and in pharmaceutical formulations as burn ointments to produce the antimicrobial effect.

Characterization and Temperature dependent DC conductivity study of bio templated nickel oxide nanoparticles (NiO) and their composites using polyaniline (PANI)

Nickel oxide (NiO) nanoparticles with an average dimension of 28 nm were prepared via the Sol-Gel method using rice starch as bio template at 500 °C for 3h. The DC conductivity of pure NiO nanoparticles measured 1.015 х 10−4 S/cm−1 at room temperature, limiting its wider use in electrical applications. Hence the conductivity of pure NiO was modified by doping polyaniline (PANI). Polyvinyl pyrrolidone (PVP) stabilized polyaniline was synthesized by the oxidative polymerization of aniline using ammonium persulfate and hydrochloric acid as a dopant. The synthesized NiO-PANI composites were subjected to temperature dependent DC conductivity study in the range of 30–150 °C and maximum conductivity 2.1129 х 10−2 S/cm−1 was obtained at 90 °C.

Metal chelate monomers based on nickel(II) cinnamate and chelating N-heterocycles as precursors of nanostructured materials

Metal chelate monomers (MCMs) have been widely used as precursors for the production of advanced functional polymers and nanomaterials. In this articel, new metal chelate monomers based on nickel(II) cinnamate (cinn) and various chelating N-heterocycles, [Ni(cinn)2(bpy)(C2H5OH)] and [Ni(cinn)2(phen)(C2H5OH)2] (bpy = 2,2′-bipyridine and phen = 1,10-phenanthroline), were first synthesized and characterized. A detailed analysis of the main stages and features of the kinetics of thermolysis of MCMs was carried out. Metal-polymer nanocomposites with a core-shell structure containing metal nanoparticles evenly distributed in a stabilizing nitrogen-containing polymer matrix were obtained by thermolysis at 300 °C. Thermolysis at 450 °C resulted in pure nickel oxide nanoparticles. The nature of the ligand has been shown to affect the structure and size of the product obtained. The tribological characteristics of nanoparticles as additives to lubricating oils were studied using the pin-on-disc tribometer. At the optimum concentration of nanoparticles, the coefficient of friction is the smallest, and an increase in the concentration above the optimum level leads to an increase in the coefficient of friction.

Synthesis and analysis of photoluminescence properties of In and Sn doped nickel oxide powders

In this paper we have reported a simple but effective route for synthesis of indium and tin doped nickel oxide nano-particles (NiO) via sol gel method. This method provides better results by controlled heat treatment. With this procedure nanoscale, well crystalline particles of the Nickel oxide and NiO:In & NiO:Sn can be synthesized. As prepared powdered material was characterized by X-ray powder diffraction technique for structural and phase analysis whereas for optical properties photoluminescence study is performed. The samples are having a combined fcc-hcp crystal structures with the crystalline size in nanometer range. Micrometer scale clusters are obtained in powdered Nickel Oxide samples. Pure NiO showed two broad peaks at 468nm & 546nm while NiO:In exhibit emission at 300nm, 334.6nm, 468.6nm and 556nm and NiO:Sn shows emissivity at 300nm, 334.6nm, 468.6nm and 556nm. Some other weak peaks also observed in the emission spectra of NiO:In & NiO:Sn at 800nm and 820nm. Thus conclusively due to the doping an increase in emissivity, intensity and change in wavelength has been observed.

Synthesis of high surface area NiO nanoparticles through thermal decomposition of mixed ligand Ni(II) Complex, [Ni(binol)(bpy)]∙CH3OH

The present work focuses on the synthesis of high surface area NiO nanoparticles through thermal decomposition of [Ni(binol)(bpy)]∙CH3OH complex as a new precursor. [Ni(binol)(bpy)]∙CH3OH (where binol = racemic-1,1′-bi-2-naphtholate and bpy = 2,2′-bipyridine) was synthesized from reaction of NiCl2(bpy) with rac-Na2(binol). The complex was characterized by elemental analysis and spectroscopy techniques of IR, UV-Vis, mass, 1H and 13C NMR. The results revealed that [Ni(binol)(bpy)]∙CH3OH was a paramagnetic tetrahedral complex. The physicochemical properties of the nanoparticles were characterized by various analysis techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and BET specific surface area. The used synthetic rout is facile and economic that makes it suitable for large scale production of pure nickel oxide nanoparticles.

Structural, morphological, optical, and electrical transport studies of poly(3-methoxythiophene)/NiO hybrid nanocomposites

Electrically conducting hybrid composites of poly(3-methoxythiophene) (PMOT) and nickel oxide (NiO) (PMOT-NiO) were synthesized by chemical oxidative method with their different proportions. The synthesized PMOT-NiO nanocomposites were characterized for optical, structural, and electrical analysis. Transmission electron microscope (TEM) depicts the morphology of the samples which revealed the transformation of thread morphology of PMOT to the clusters in PMOT-NiO hybrid composites. The structural and optoelectronic properties of hybrid composites were quite different from those of pure PMOT and NiO nanoparticles which were attributed to the chemical interaction between PMOT and NiO nanoparticle. X-ray diffraction (XRD) confirmed the cubic structure of NiO with an average crystallite size of 5 nm. The nanocomposites had lower diffraction peak intensities and smaller interplanar spacing as compared to NiO. Ultraviolet (UV) spectra and fluorescence spectra (PL) showed that the optical behavior of nanocomposites was far superior to PMOT and NiO separately. FTIR spectra revealed that the absorption of PMOT was affected by the presence of NiO nanoparticle. The room-temperature electrical conductivity was increased up to 4.2 × 10−7 Ω/cm−1 with increase in the concentration of NiO content in PMOT-NiO hybrid composites.

Polypyrrole-NiO hybrid nanocomposite: Structural, morphological, optical and electrical transport studies

Polypyrrole (PPy)-nickel oxide (NiO) hybrid nanocomposite thin films have been prepared by spin coating method. The PPy–NiO hybrid nanocomposites were characterized for structural, morphological, optical and electrical analysis, and the results were compared with the pure PPy films. The structural and optoelectronic properties of PPy–NiO hybrid nanocomposites are quite different from those of pure PPy and NiO nanoparticles, which were attributed to the strong interaction between the PPy and NiO nanoparticles. The XRD pattern shows that broad peak of PPy becoming weaker on increasing the content of NiO nanoparticles in the PPy–NiO hybrid nanocomposites. Also the diffraction peaks of NiO nanoparticles in PPy–NiO (10–50wt%) nanocomposites were found to shift to lower 2θ values. The morphological studies revealed that the transformation of granular morphology of PPy to the nanospheres and clusters in the PPy–NiO hybrid nanocomposites. FTIR spectra of PPy–NiO hybrid nanocomposites, revealed that the main absorption at 1204cm−1 and 1559cm−1 are affected by the presence of NiO nanoparticle in pure PPy and get shifted to 1216cm−1 and 1570cm−1 respectively indicates, insertion of NiO nanoparticles in the PPy–NiO hybrid nanocomposite. UV–vis absorption spectrum of PPy corresponding to λmax=442nm is blue shifted to λmax=375nm in the PPy–NiO hybrid nanocomposites, reveals strong interaction between PPy and NiO nanoparticles. The room temperature dc electrical conductivity is increased from 8.66×10−9 to 4.08×10−7(Ω/cm)−1 as the content of NiO nanoparticles increased from 10 to 50 inwt% in the PPy–NiO hybrid nanocomposites.

Synthesis and Characterization of NiO Nanoparticles by Sol–Gel Method

Due to the outstanding electrical, magnetic and catalytic properties, nickel oxide (NiO) has been received considerable attention during the past decades. In this study, NiO nanoparticles were prepared by sol­gel method, which is one of the simplest and lowest-cost techniques. The synthesis was accomplished by using Poly(alkylene oxide) block copolymer as the surfactant, and Ni(NO3)2·6H2O as the inorganic precursor. The effect of experimental parameters, such as calcination temperatures and H2O concentration on the NiO nanoparticles formation were investigated. TGA, XRD, SEM, TEM and N2 adsorption­desorption isotherms were used to characterize the microstructure and specific surface area of the samples. TGA and FTIR analyses demonstrated that copolymers were expelled at 573K. The formation of NiO nanoparticles and their structural features were greatly dependent on the calcination temperature. The sample calcined at 923K was composed of pure NiO nanoparticles as shown by XRD. As H2O concentration was increased, the reoxidation process of metallic Ni to form NiO would reduce, but it would not affect the structural type of NiO nanoparticles. In general, the addition of water would weaken and inhibit oxidation effects. The temperature of stable metallic Ni was increased up to 823K. The specific surface area evaluated from the N2 adsorption­desorption indicated that the samples consisting of non-porous NiO nanoparticles. Increasing H2O addition resulted in an increase of specific surface area of nanocrystalline NiO powder. [doi:10.2320/matertrans.M2012244]