Green gelatine-assisted sol–gel synthesis of ultrasmall nickel oxide nanoparticles

Nickel oxide nanoparticles (NiO NPs) were synthesised using a sol–gel method in a gelatinous medium. Gelatine was used as a size-limiting polymerisation agent for the growth of NiO NPs. X-ray diffraction (XRD) analysis revealed that increasing the calcination temperature increased the crystallite size and decreased the size of the lattice constant. The size-strain plot method (SSP) was used to measure the individual contribution of grain sizes and micro strain on the peak broadening of NiO NPs. Transmission electron microscopy (TEM) showed the ultrasmall size of the NiO NPs with a narrow size distribution(10±0.2 nm). The band gap value of NiO NPs was calculated using ultraviolet–visible (UV–Vis) spectroscopy and decreased with increased calcination temperature.     

NiO nanoparticles catalyzed three component coupling reaction of aldehyde,amine and terminal alkynes

This work reports a simple, microwave assisted facile and efficient protocol for the synthesis of nickel oxide nanoparticles (NiO NPs) by using only two reagents i.e. nickel acetate and benzylamine. Nickel acetate reacts with benzylamine to give nickel hydroxide and which on calcination give NiO NPs. Benzylamine plays various role in this reaction such as solvent, reactant and stabilizer. The developed protocol is faster, economically viable and environmentally benign as it is additive free. Transmission electron microscope (TEM) reveals the particles are in nano range and X-ray diffraction (XRD) data shows crystalline nature of NiO NPs. The prepared NiO NPs were used as heterogeneous catalyst for three component coupling reaction of aldehyde, amine with terminal alkynes. The catalyst could be recycled up to fourth run without significant loss in the catalytic activity.     

Fe–Co co-doping effects on antiferromagnetic core of NiO nanoparticles

The Fe and Co single and co-doping effects on the structural and magnetic properties of NiO nanoparticles (NPs) have been studied. The Fe and Co doping into NiO system did not induce any other possible secondary phase (other than NiO) and the average crystallite size was found to be in a narrow range of 33–40 nm which is suitable for studying the doping effects. Room temperature ferromagnetic resonance (FMR) measurements demonstrated the existence of a net magnetization in antiferromagnetic (AFM) NiO NPs which was observed to be increased with an increasing Fe doping and decreasing Co doping concentration. The scattered differential FMR signal for 8% Co doped NiO NPs revealed the presence of randomly oriented magnetic moments in the core of the NPs. However, decreasing the Co doping concentration and increasing the Fe doping concentration increased the degree of homogeneity of the spin structure in the system. The M ? H loops taken at room temperature with S-like shape confirmed the presence of a weak ferromagnetism in the Fe doped samples in accordance with FMR analysis and attributed to the double exchange mechanism in these NPs. In ZFC/FC curves, a small peak at low temperatures, in the range of 9–18 K for all the samples, indicates the magnetization contribution from the uncompensated surface spins of these NPs. In addition, a relatively broad peak for higher Fe doping concentrations at higher temperatures indicates the onset of magnetization from the core of these NPs, where Fe and Ni ions may couple parallel or anti-parallel to each other. In summary, Co–Fe co-doping induced a core magnetization in AFM NiO NPs system and makes it attractive for various magnetic applications.     

Electrodeposition of nickel oxide nanoparticles on glassy carbon surfaces: application to the direct electron transfer of tyrosinase

This work describes the performance of a tyrosinase/nickel oxide nanoparticles/glassy carbon (Tyr/NiO NPs/GC) electrode. This electrode was prepared by first applying a NiO NPs electrochemical deposition onto the GC electrode surface and then tyrosinase immobilization was applied to the surface of electrodeposited NiO NPs. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) procedures demonstrated the existence of different NiO NP geometrical structures. These geometrical structures could lead to better immobilization of proteins on their surfaces. The copper containing enzyme tyrosinase successfully achieved electrical contact with the electrode because of the unique structural alignment of tyrosinase enzyme on the nanometer-scale nickel oxide surfaces. This method could be suitable for application to nanofabricated devices facilitating better performance. It was concluded that tyrosinase can be effectively applied to nanometer-scale nickel oxide surfaces.     

Phytoextract-mediated synthesis of Cu doped NiO nanoparticle using cullon tomentosum plant extract with efficient antibacterial and anticancer property

In the present study, nickel oxide (NiO) and copper-doped nickel oxide (NiCuO) nanoparticles (NPs) were successfully synthesized using Cullen tomentosum plant extract with the co-precipitation method. This work focuses on the Phyto-mediated synthesis and characterization of NPs for their biological applications. Phytochemicals that exist in the plant extract acts as reducing and capping agent. The successful formation of the NPs was validated by various analysis as XRD, FESEM, EDAX, FT-IR, UV–Vis, and Photoluminescence. According to XRD studies, the average crystallite size of NiO and NiCuO NPs is 36 nm and 31 nm, respectively. The river stone and nanoflower like morphology for NiO and NiCuO NPs are confirmed by FESEM image. Furthermore, the synthesized NPs were tested against Gram-positive (Bacillus subtilis, Streptococcus pneumoniae) and Gram-negative (Klebsiella pneumoniae, Escherichia coli) bacteria, which showed enhanced antibacterial activity of NiCuO NPs. The cytotoxicity of NPs was investigated against human breast cancer cells (MDA-MB-231) and fibroblast L929 cell lines. Also, the IC₅₀ value for human breast cancer cells is 11.8 μg/mL. According to these findings, NiCuO NPs are potential nanomaterials with advanced healthcare uses.     

磁性Ni/NiO纳米颗粒的制备及其在蛋白分离上的应用

用1∶323的硝酸镍和尿素制备出前驱物Ni2+-oligomer,于450℃下热解2 h,得到平均粒径为2 nm的磁性Ni/NiO纳米颗粒;再利用Ni2+与组氨酸的特异性结合,将Ni/NiO纳米颗粒表面修饰上组氨酸,得到平均粒径为10 nm的磁性his-Ni/NiO纳米颗粒,在大肠杆菌体内进行蛋白吸附并在体外进行提纯。结果表明,his-Ni/NiO纳米颗粒洗脱下来的蛋白与大肠杆菌中的蛋白种类一致,该研究为蛋白分离和纯化提供了一条新思路。     

Calcium-dependent cyto- and genotoxicity of nickel metal and nickel oxide nanoparticles in human lung cells

Background

Genotoxicity is an important toxicological endpoint due to the link to diseases such as cancer. Therefore, an increased understanding regarding genotoxicity and underlying mechanisms is needed for assessing the risk with exposure to nanoparticles (NPs). The aim of this study was to perform an in-depth investigation regarding the genotoxicity of well-characterized Ni and NiO NPs in human bronchial epithelial BEAS-2B cells and to discern possible mechanisms. Comparisons were made with NiCl₂ in order to elucidate effects of ionic Ni.

Methods

BEAS-2B cells were exposed to Ni and NiO NPs, as well as NiCl₂, and uptake and cellular dose were investigated by transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry (ICP-MS). The NPs were characterized in terms of surface composition (X-ray photoelectron spectroscopy), agglomeration (photon cross correlation spectroscopy) and nickel release in cell medium (ICP-MS). Cell death (necrosis/apoptosis) was investigated by Annexin V-FITC/PI staining and genotoxicity by cytokinesis-block micronucleus (cytome) assay (OECD 487), chromosomal aberration (OECD 473) and comet assay. The involvement of intracellular reactive oxygen species (ROS) and calcium was explored using the fluorescent probes, DCFH-DA and Fluo-4.

Results

NPs were efficiently taken up by the BEAS-2B cells. In contrast, no or minor uptake was observed for ionic Ni from NiCl₂. Despite differences in uptake, all exposures (NiO, Ni NPs and NiCl₂) caused chromosomal damage. Furthermore, NiO NPs were most potent in causing DNA strand breaks and generating intracellular ROS. An increase in intracellular calcium was observed and modulation of intracellular calcium by using inhibitors and chelators clearly prevented the chromosomal damage. Chelation of iron also protected against induced damage, particularly for NiO and NiCl₂.

Conclusions

This study has revealed chromosomal damage by Ni and NiO NPs as well as Ni ionic species and provides novel evidence for a calcium-dependent mechanism of cyto- and genotoxicity.

     

Polydopamine-Assisted Bi-Functional Modification of NiO Anode for Enhanced Lithium-Ion Storage Performance

The blooming requirement of high-performance energy storage systems has aroused the thirst for advanced energy storage materials. As a high capacity anode, however, the application of NiO nanoparticles (NiO NPs) is hindered by intractable issues of dramatic volume change, intrinsic low electronic conductivity, and severe aggregation tendency during lithiation/delithiation. Herein, a polydopamine (PDA) assisted bi-functionalization strategy for fabricating of PDA@NiO-CNT composites for fast and durable lithium storage is reported. In this composite, CNTs intertwine to form a network to ensure sufficient electrolyte infiltration and act as a highly conductive system to motivate fast charge transmission. The strong binding affinity of PDA facilitates bonding between NiO NPs and CNTs, which not only forms uniform and flexible PDA coating but also ensures homogeneous distribution of NiO NPs on CNTs network. Therefore, the bi-functional modified PDA@NiO-CNT electrode possesses high conductivity, alleviates volume change and aggregation of NiO NPs during cycling, achieves a reversible capacity of 1326 mAh g⁻¹ at 100 mA g⁻¹, a rate capability of 215 mAh g⁻¹ at 2000 mA g⁻¹ and a cycling stability with 78% capacity retention after 250 cycles. This bi-functional modification approach manifests its prospective potential for architecting other electrode materials toward high-performance electrochemical devices.     

Semi shield driven p-n heterostructures and their role in enhancing the room temperature ethanol gas sensing performance of NiO/SnO2 nanocomposites

The demand for the development of gas sensors operable at room temperature is increasing due to the uncountable drawbacks of high temperature gas sensors. This contribution describes the fabrication of room temperature ethanol sensor. The synthesis of NiO semi shielded SnO₂ (NiO/SnO₂) nanocomposites (NCs) was done via a simple two-step process, started with co-precipitation technique and then followed by sol-gel method. High resolution electron microscope (HRTEM) results indicated the semi shielding of NiO on SnO₂ nanoparticles (NPs). Surface morphological studies of the fabricated sensors show the porous nature of the samples which further helps in enhanced sensing response. X-ray photoelectron spectroscope (XPS) results of NiO/SnO₂ NCs revealed the valence states of Ni (+2) and Sn (+4). Excellent gas sensing response of the NiO/SnO₂ sensor towards ethanol at room temperature was observed from the gas sensing studies. The response of NiO/SnO₂ (∼140) was nearly 9 times higher than SnO₂ sensor (∼15) and nearly 11 times higher than NiO sensor (12.98) towards 100 ppm ethanol at room temperature. The observed response and recovery times of NiO/SnO₂ were 23 s and 13 s respectively. The p-n heterostructure formed between p-NiO and n-SnO₂, and high chemical sensitization and catalytic activity of the NiO are the main contributors for the excellent sensing performance of NiO/SnO₂ sensor.     

Non-Covalent Synthesis of Metal Oxide Nanoparticle–Heparin Hybrid Systems: A New Approach to Bioactive Nanoparticles

Heparin has been conjugated to Fe₃O₄, Co₃O₄, and NiO nanoparticles (NPs) through electrostatic interactions, producing colloidal suspensions of hybrid metal oxide heparin NPs that are stable in water. Negative zeta potentials and retention of heparin’s ability to capture toluidine blue indicate that heparin’s negative charges are exposed on the surface of the coated NPs. IR results confirmed the formation of nanohybrids as did NMR experiments, which were also interpreted on the basis of toluidine blue tests. Transmission electron microscopy results revealed that the heparin coating does not modify the shape or dimension of the NPs. Dynamic light scattering and negative zeta potential measurements confirmed that heparin surface functionalisation is an effective strategy to prevent NP aggregation.     

Dielectric and electrical properties of La@NiO SNPs for high-performance optoelectronic applications

A successful flash combustion synthesis of NiO spherical nanoparticles with various contents of lanthanum (La) doping (La@NiO SNPs) with remarkably enhanced dielectric and electrical properties are reported. Single phase has been confirmed through X-ray diffraction and FT-Raman spectroscopic analysis. Increasing La content in NiO reduced the crystallite size by 341% to 6.65 nm from 22.70 nm. The composition of elements in the final product was assessed via EDX analysis. Moreover, monophasic La@NiO SNPs synthesis with size reduction was observed using field emission scanning electron microscopy (FESEM). A red shift in optical energy gaps (3.52–3.26 eV) was observed with increasing La contents from pure to 10 wt%. Capacitance (109–964 PF), impedance (9.41 × 10⁴–1.67 × 10⁴ kΩ), dielectric constant (100–967), dielectric loss (335–10666), and electrical conductivity (4–5 S/m) values were remarkably improved with La doping. The current (I)–voltage (V) characteristics of pure and La@NiO NPs were performed under the biased voltage of ±20 V. Current was noticed in the range of (3.81 × 10^?4–9.91 × 10^?3 amp) at pure, 1.0, 3.0, 5.0, and 10 wt% of La@NiO NPs. Enhancements in the dielectric and electrical properties of as-synthesized NPs make them suitable for optoelectronics uses.     

Effect of Bi contents on key physical properties of NiO NPs synthesized by flash combustion process and their cytotoxicity studies for biomedical applications

Nickel oxide has tremendous applications in the field of biomedicine. In this study, NiO nanoparticles were synthesized with different Bi contents (NiO@Bi; 0.0–7.5 wt%), and multifunctional usages were investigated. Structural confirmation was conducted through XRD and Raman studies, which revealed a monophasic cubic system. With increasing Bi content, broadening of the XRD and Raman peaks were observed, indicating a reduction in particle size. The crystallite size was found to be in the range of 10–26 nm. The decrease in particle size was confirmed through dynamic light scattering measurement. The homogeneous distribution of all elements and the presence of Bi were detected by an EDX/SEM e-mapping study. Field emission electron microscopy confirmed the formation of spherical shape nanoparticles. The grain size was reduced from 30 nm to 10 nm with Bi content, in accordance with XRD and Raman results. The Kubelka-Munk method was employed to determine the effect of Bi content on the optical band gap of NiO. The energy gap was reduced with Bi content in the range of 3.32–3.50 eV. Antimicrobial and in vitro cytotoxic characteristics of the prepared NPs were also studied. The results revealed that all NiO@Bi NPs had negligible antimicrobial activity and no cytotoxic effects on both normal and activated splenic cells. The in vivo acute cytotoxicity study indicated no cytotoxic effects on liver and kidney functions. The prepared NiO@Bi NPs were implanted in living organisms without hepatic/renal toxicity, demonstrating excellent biocompatibility, cell viability, and superior quality of nanocrystals, suggesting that the prepared NPs are ideal candidates for antibacterial and biomedical applications.     

Structure sensitivity of oxide surfaces: the adsorption and reaction of carbon monoxide and formic acid on NiO(100) and NiO(111)

The adsorption and reaction of CO and HCOOH on the NiO(100)/Mo(100) and NiO(111)/Mo(110) surfaces have been studied using temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS). Significant differences have been found for the two faces of NiO regarding the adsorption and reaction of HCOOH. While molecularly adsorbed formic acid is stable up to 200 K on the NiO(100) surface, formic acid decomposition to formate occurs on the NiO(111) surface at 100 K. Upon heating to 700 K, most of the formate on the NiO(111) surface dehydrogenates or dehydrates, while 70% of the formate species on the NiO(100) surface desorbs as molecular formic acid. With respect to CO adsorption, the NiO(111) surface shows a slightly higher binding energy than does the NiO(100) surface.     

Enhancing the ultraviolet photosensing properties of nickel oxide thin films by Zn–La co-doping

In this work, co-doping effects of transition (Zn) and rare-earth (La) elements on the crystalline structure, surface morphology, photoluminescence, optical and photosensing properties of NiO thin films are studied. NiO, NiO:Zn(1%), NiO:La(1%), and NiO:Zn(1%):La(1%) thin films are fabricated using the nebulizer spray pyrolysis (NSP) method. X-ray diffraction study revealed the cubic NiO structure of all the films. Photoluminescence (PL) spectra of thin films exhibit various emission peaks centered at the wavelengths of 387, 414, 437, 451, 477, and 521 nm. The optical bandgap energy (E_g) values are found to be 3.46, 3.43, 3.39 and 3.33 eV for NiO, NiO:Zn(1%), NiO:La(1%) and NiO:Zn(1%):La(1%) thin films, respectively. The fabricated (Zn, La) co-doped NiO i.e., NiO:Zn(1%):La(1%) photo-detector exhibits highest responsivity (R), external quantum efficiency (EQE) and detectivity (D*) values of 0.50AW^-1, 169% and 14.5 × 10⁹ Jones, respectively as compared to NiO, NiO:Zn(1%) and NiO:La(1%) photo-detectors. The present study revealed that the transition and rare-earth elements co-doping can be an effective approach for tuning the various physical properties of semiconducting oxide films.     

Influence of nickel oxide nanolayer and doping in organic light-emitting devices

Here we report the effect of introducing nickel oxide (NiO) on the performance of organic light-emitting devices (OLEDs) based on small molecules. For the purpose of aligning the NiO deposition with the conventional OLED process, we employed a thermal evaporation method using the NiO powders. To understand the influence of the NiO introduction, we fabricated two types of devices: (1) OLED with the NiO nanolayer and (2) OLED with the NiO-doped hole transport layer. Results show that the NiO introduction improved the hole injection in both types of OLED. However, the device with the NiO nanolayer exhibited greatly improved efficiency, whereas the efficiency was significantly lowered for the device with the NiO-doped hole transport layer.     

Structure and room-temperature ferromagnetism evolution of Sn and Mn-doped NiO synthesized by a sol-gel process

The development of room temperature ferromagnetism is imperative for energy systems such as data storage in computers and spintronics. Herein we report a room temperature ferromagnetic study of Sn and Mn doped nickel oxide synthesized by sol gel method. The size and morphology of the samples are calculated using XRD and TEM analysis. The XRD and Fourier transform infrared (FTIR) results indicate that the synthesized NiO powders have a pure cubic structure. The variation in lattice parameters has been studied using the Rietveld refinement of X-ray diffraction pattern. The addition of dopants does not affect the structure of NiO. The presence of dopants in the doped NiO samples has been confirmed with Energy Dispersive Spectroscopy (EDS) analysis. The Photoluminescence (PL) spectrum shows enhanced luminescence intensity for Sn doped NiO than Mn doped NiO. The magnetic properties of the samples have been studied using Vibrating sample magnetometry (VSM). The pure and Mn doped NiO samples are found to exhibit ferromagnetism. The Sn doped NiO samples exhibit superparamagnetism making them suitable for applications in ferrofluids and as contrast agents for magnetic resonance imaging. The coercivity and magnetization of the Mn doped NiO samples are found to be enhanced compared to the pure NiO. The Sn doped NiO samples have very low value of coercivity compared with both pure and Mn doped NiO samples. The observed room temperature ferromagnetism in doped NiO makes it a suitable candidate for DMS devices such as MR imaging and magnetic delivery.     

Synthesis and characterization of nano‐sized NiO and its surface catalytic effect on poly(vinyl alcohol)

Nickel oxide (NiO) nano particle is synthesized by Ultrasound assisted one pot method and thus synthesized nano NiO is mixed with poly(vinyl alcohol) (PVA) to prepare the PVA/NiO nanocomposite. The influence of the composition on the structural modification on the composite is evaluated. The particle size and morphology of NiO nano material is confirmed by HRTEM. The structure and properties of the PVA/NiO nanocomposite material are characterized by FTIR, XRD, UV–Visible spectroscopy, DSC, TGA, and HRTEM. The synthesized PVA nanocomposite underwent hydrolytic oxidation reaction assisted by the effect of nano‐sized NiO. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Chemical modification in and on single phase [NiO]0.5[Al2O3]0.5 nanopowders produces “chocolate chip-like” Nix@[NiO]0.5-x[Al2O3]0.5 nanocomposite nanopowders

Phase-pure [NiO]_0.5[Al₂O₃]_0.5 spinel nanoparticles (NPs) with limited aggregation were obtained via liquid-feed flame spray pyrolysis (LF-FSP) by combusting metalloorganic precursor solutions. Thereafter “chocolate chip-like” Ni_x[NiO_0.5-x][Al₂O₃]_0.5 nanoparticles consisting of primary [NiO_0.5-x][Al₂O₃]_0.5 particles with average particle sizes of 40-60 nm decorated with Ni metal particles (<10 nm in diameter) dispersed on the surface were synthesized by heat treating the spinel NPs at 800°C/7 h in flowing 5% H₂:N₂ 100 mL/min in a fluidized bed reactor. The synthesized materials were characterized using TEM, XRD, FTIR, and TGA/DTA. The Ni depleted areas consist primarily of γ-Al₂O₃. The Ni content (800°C) was determined by TGA to be ≈11.3 wt.% based on TGA oxidation behavior. The successful synthesis of such nanocomposites with limited aggregation on a high temperature support provides a facile route to synthesize well-defined NP catalysts. This work serves as a baseline study for an accompanying paper, wherein thin, flexible, dense films made from these same NPs are used as regenerable catalysts for carbon nanotube syntheses.     

纳米氧化亚镍包覆Al复合粒子的制备

为了获得具有良好红外吸收特性及低发射率复合颜料,通过将纳米NiO复合于片状金属铝粉表面的方法,获得了复合效果好的纳米NiO/Al复合粒子.为了保证复合物的红外伪装性能,通过对复合前驱体Ni₂CO₃(OH)₂/Al的热分析,确定了对复合物的热处理温度.通过对复合物热处理前后的电镜照片分析,发现热处理前复合物表面是由线状的Ni₂CO₃(OH)₂交织而成的,而热处理后则变成了由纳米球状NiO粒子连接而成的球链.这种现象在同类研究中尚未见报道.对比所制备的纳米NiO/Al和NiO的XRD图谱,发现纳米NiO/Al中的NiO衍射峰宽化,表现出纳米粒子的特征,由半高宽计算出其晶粒粒径为12 nm.     

Developing high-transmittance heterojunction diodes based on NiO/TZO bilayer thin films

In this study, radio frequency magnetron sputtering was used to deposit nickel oxide thin films (NiO, deposition power of 100 W) and titanium-doped zinc oxide thin films (TZO, varying deposition powers) on glass substrates to form p(NiO)-n(TZO) heterojunction diodes with high transmittance. The structural, optical, and electrical properties of the TZO and NiO thin films and NiO/TZO heterojunction devices were investigated with scanning electron microscopy, X-ray diffraction (XRD) patterns, UV-visible spectroscopy, Hall effect analysis, and current-voltage (I-V) analysis. XRD analysis showed that only the (111) diffraction peak of NiO and the (002) and (004) diffraction peaks of TZO were observable in the NiO/TZO heterojunction devices, indicating that the TZO thin films showed a good c-axis orientation perpendicular to the glass substrates. When the sputtering deposition power for the TZO thin films was 100, 125, and 150 W, the I-V characteristics confirmed that a p-n junction characteristic was successfully formed in the NiO/TZO heterojunction devices. We show that the NiO/TZO heterojunction diode was dominated by the space-charge limited current theory.