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Facile Synthesis, Characterization and Enhanced Photocatalytic Activities of NiWO <sub/>4</sub> /Nitrogen Doped Reduced Graphene Oxide Nanocomposites
摘要： In this study, we report the synthesis of NiWO4/nitrogen doped reduced graphene oxide nano composite by one-pot hydrothermal method. The NiWO4 nano particles were dispersed uniformly on graphene sheets. The as prepared NiWO4, NiWO4/5% rGO and NiWO4/N-5% rGO composites were analytically characterized by Powder X-ray diffraction (XRD), Raman spectroscopy, Diffuse re?ectance spectroscopy (DRS-UV), Scanning electron microscopy (SEM) and N2 adsorption–desorption isotherm. The photocatalytic performances of the synthesized composites were evaluated towards the photo degradation of congo red (CR) under visible light radiation. The synthesized catalysts showed remarkable photocatalytic activity in the degradation of CR. Among the catalysts NiWO4/N-5% rGO showed the highest decolourization of congo red (92%) under visible light irradiation. This high activity is attributed to its high e? transport property. Our results provide an invaluable methodology for designing high-performance photo-catalysts for new energy applications.
关键词： Wolframite,Nickel Tungstate,Degradation,Graphene,Congo Red
更新于2025-09-09 09:28:46
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Temperature and frequency effect on the electrical properties of bulk nickel phthalocyanine octacarboxylic acid (Ni-Pc(COOH)8)
摘要： The AC conductivity of nickel phthalocyanine octacarboxylic acid was investigated from 100 Hz to 1 MHz and temperature from 290 to 423 K. The AC conductivity was found to vary with frequency (σ(f)) and form two dispersion regions; the associated exponent factor “s” values were found to vary from 1.17 to 1.34 and from 0.42 to 0.67 (< 1). The value and temperature dependent of s are found in agreement with conduction mechanism models of large-polaron tunneling and the correlated barrier hopping, at the first and the second regions, respectively. The real and the imaginary parts of the dielectric constant were observed to decrease as the frequency increases indicating the pronounce contribution of low-frequency polarization mechanisms. Furthermore, the activation free energy ?F, enthalpy ?H, and entropy ?S of the sample were calculated as well.
关键词： enthalpy,polarization mechanisms,AC conductivity,activation free energy,dielectric constant,nickel phthalocyanine octacarboxylic acid,entropy
更新于2025-09-09 09:28:46
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A Computational Study on the Variation of Bandgap Due to Native Defects in Non-Stoichiometric NiO and Pd, Pt Doping in Stoichiometric NiO
摘要： This paper presents a computational study of non-stoichiometric nickel oxide in a 64-cell NiO system to model and validate localized heating effects due to nanosecond laser irradiation. Variation in the Bandgap of NiO is studied as a function of varying concentrations of native defects, ranging from 0 to 25%. It is observed that there is a slight increase in the bandgap from 3.80 eV for stoichiometric NiO to 3.86 eV for Ni-rich NiO and to 3.95 eV for O-rich NiO. It is hence deduced that the experimental laser irradiation leads to simultaneous reduction of Ni2+ ions and the oxidation of NiO as the number of laser pulses increase. As well, a detailed study on the effects of doping nickel family elements, i.e., palladium (Pd) and platinum (Pt), in stoichiometric NiO is presented. A bandgap decrease from 3.8 eV for pure NiO to 2.5 eV for Pd-doping and 2.0 eV for Pt-doping for varying doping concentrations ranging from 0–25% Pd, Pt, respectively, is observed.
关键词： dopants,platinum,palladium,nickel oxide,bandgap
更新于2025-09-04 15:30:14
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Nickel(II) Coordination Complex Constructed from Benzimidazole and Pyridine-2,6-dicarboxylate Co-ligands: Synthesis, Crystal Structure, Thermal Behavior, and Photoluminescence
摘要： A Ni(II) complex, [Ni(pydca)(bim)3] (pydca = pyridine-2,6-dicarboxylate, bim = benzimidazole) has been prepared by hydrothermal synthesis. It is characterized by elemental analysis, IR and thermal analysis. The crystal structure is determined by single crystal X-ray diffraction. The mononuclear complexes are linked by N–H···O hydrogen bonds. The title complex has good thermal stability and exhibits good fluorescence properties in ethanol solution at room temperature.
关键词： crystal structure,Nickel(II) complex,6-dicarboxylate,hydrothermal synthesis,benzimidazole,photoluminescence,thermal behavior,pyridine-2
更新于2025-09-04 15:30:14
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[IEEE 2018 International Conference on Advanced Science and Engineering (ICOASE) - Duhok, Kurdistan Region, Iraq (2018.10.9-2018.10.11)] 2018 International Conference on Advanced Science and Engineering (ICOASE) - Characterization of Black Nickel Solar Absorber Coatings on Brass Substrates
摘要： Solar Selective coatings have radiative characteristics which vary with wavelength. They are characterized by their high absorbance (α) in the visible region and low thermal emittance (ε) (or high reflection) beyond the visible region of the sun spectra. These coatings materials are of very great importance in the field of renewable energy sources (solar energy applications). In the present study, the influence of process parameters like the current density, concentration of particles, time of deposition, the thickness of the electrodeposited nickel (Ni), etc. was investigated. The objective of the research is to study solar selective coatings used in solar thermal collectors. i.e. black nickel (B-N) coatings, electrodeposited (ED) over brass substrates. Preparation and characterization of B-N coatings over brass substrates was performed. Low-cost solar selective absorbers (ED of B-N on brass) have been obtained. Trial to get rid of some structures or materials which are harm to the environment. (i.e. car batteries, by using lead sheets from recycled car battery as an anode during ED of B-N coating) was achieved. Reflectance measurements were used to evaluate both, (α) and (ε) of the coatings. The measurements of total or diffuse reflectance of samples were performed with instruments equipped with integrating spheres. Electrodeposited (ED) of black nickel BN on brass substrate has a moderate selectivity (α /ε =2.63, when α =0.95). The durability tests were carried out in the form of elevated temperature exposure in air (250 C0), temperature cycling (30-100 C0), and humidity tests (up to 90 % RH). The coatings have been re-characterized after ageing tests, using spectrophotometry and other techniques, such as X-ray techniques. Durability testing of the ED B-N coatings indicates that they are sensitive to humidity testing. However, efficient absorbers were obtained by using low-cost technique. Durability testing of the ED B-N coatings indicates that they are sensitive to humidity testing.
关键词： Solar selective coating,Black nickel coating,Electro-deposition
更新于2025-09-04 15:30:14
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Annealing effects on recombinative activity of nickel at direct silicon bonded interface
摘要： By performing capacitance transient analyses, the recombination activity at a (110)/(100) direct silicon bonded (DSB) interface contaminated with nickel diffused at different temperatures, as a model of grain boundaries in multicrystalline silicon, was studied. The trap level depth from the valence band, trap density of states, and hole capture cross section peaked at an annealing temperature of 300 ?C. At temperatures (cid:62)400 ?C, the hole capture cross section increased with temperature, but the density of states remained unchanged. Further, synchrotron-based X-ray analyses, microprobe X-ray fluorescence (μ-XRF), and X-ray absorption near edge structure (XANES) analyses were performed. The analysis results indicated that the chemical phase after the sample was annealed at 200 ?C was a mixture of NiO and NiSi2.
关键词： direct silicon bonded interface,recombination activity,annealing effects,X-ray analyses,nickel,capacitance transient analyses
更新于2025-09-04 15:30:14
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Impact of heterogeneities and surface roughness on pXRF, pIR, XRD and Raman analyses: Challenges for on-line, real-time combined mineralogical and chemical analyses on drill cores and implication for “high speed” Ni-laterite exploration
摘要： On-line, real-time chemical and mineralogical analyses on drill cores are highly demanded by mining companies. However, they are a challenge because of drill core surface state and sample heterogeneities. We selected four rock samples: highly porous, siliceous breccia and serpentinized harzburgite coming from the base of a nickel laterite profile in New Caledonia which were sonic drilled, and fine grained, homogeneous sandstone and coarse grained granite which were diamond drilled and provided by Eijkelkamp Sonic Drill with unknown origin. The samples were analyzed at five surface states (diamond or sonic drilled, cut as squares, polished at 6 and 0.25 microns, powdered < 80 microns) by portable XRF spectroscopy (pXRF) in mining and soil modes and portable infrared spectroscopy (pIR, Visible and Near Infrared - Short Wave Infrared range (VNIR-SWIR)). A total of 52 pXRF and 200 pIR analyses were performed per sample at each surface state. This study shows that the surface state has minor influence on the results of the portable instruments. By comparing pIR and pXRF results with laboratory devices (Raman spectroscopy, XRD with Rietveld refinement, XRF spectroscopy and ICP-AES), we evidence the lower and less accurate information obtained from handheld instruments in terms of chemistry and mineralogy. The porosity and grain size effect on the measurement need to be taken into consideration for on-line drill core analyses. We show that the combination of complementary analytical techniques helps to overcome the drawbacks of the core texture and of the precision of portable instruments in order to define the regions of interest (ROI) for mining companies. We also demonstrate that a precise pXRF calibration is mandatory and that the concentration of light elements (Si, Mg), even if not accurate, shows sufficient contrast along the lateritic profile for ROI definition.
关键词： drill cores,nickel,portable instruments,surface effects,garnierite
更新于2025-09-04 15:30:14
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Nickel ion detection by imidazole modified carbon dots
摘要： Nickel ions (Ni2+) were detected by a new imidazole modified carbon dots (CDs) based on fluorescence quenching method. Structural characterization of CD-imidazole quantum dots were accomplished by transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). Spectroscopic properties were characterized by ultraviolet absorption spectrum and fluorescence spectrum. Ni2+ concentration showed good linear relationship with fluorescence quenching efficiency in the range of 6-100 mM (R = 0.99) and the limit of detection (LOD) was 0.93 mM. Imidazole modified CDs have strong selectivity of Ni2+ compared with other metal ions in aqueous solution. These results demonstrated that the fluorescence sense platform based on imidazole modified CDs can be applied to Ni2+ detection in environment.
关键词： Nickel ions,Fluorescence quenching,Carbon dots-imidazole quantum dots
更新于2025-09-04 15:30:14
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Nickel Nanowires Combined with Surface-Enhanced Raman Spectroscopy: Application in Label-Free Detection of Cytochrome c-Mediated Apoptosis
摘要： Intrinsic properties of nickel have enabled its wide applications as an effective catalyst. In this study, nickel nanowires (Ni NWs) as electron donors for oxidized cytochrome c (Cyt c) are investigated, which are NW diameter, temperature, and pH value-dependent. The reductive and magnetic properties facilitate the Ni NWs to rapidly and conveniently reduce Cyt c in complicated biological samples. Moreover, we find that the Ni NWs combined with resonance Raman spectroscopy have specificity towards Cyt c detection in real biological samples, which is successfully used to distinguish the redox state of the released Cyt c from isolated mitochondria in apoptotic Hela cells. Moreover, rapid label-free Cyt c quantification can be achieved by surface-enhanced Raman spectroscopy with a limit of detection range of 1 nM and long concentration linear (1nM?1μM). The proposed Ni NWs-based reduction approach will significantly simplify the traditional biological methods and has great potential in the application of Cyt c-related apoptotic studies.
关键词： nickel nanowires,surface-enhanced Raman spectroscopy,cytochrome c,label-free detection,apoptosis
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE XXVII International Scientific Conference Electronics (ET) - Sozopol, Bulgaria (2018.9.13-2018.9.15)] 2018 IEEE XXVII International Scientific Conference Electronics - ET - Effect of Electroless Nickel Deposition on the Breakdown Voltage of Nanoporous Aluminium Oxide
摘要： Anodic aluminium oxide films were formed in various acidic solutions and further covered by Ni and Cu coatings. Certain of them were reanodized to thicken their barrier sub-layer. As a final outcome, printed circuit board-like multi-layer structure Al/Al2O3/Ni/Cu is produced. In this case, it is clearly demonstrated that the breakdown voltage of anodic oxide depends on its overall thickness, barrier sub-layer thickness, metal coating availability as well as to some extent on pore diameter.
关键词： anodic aluminium oxide,electroless nickel deposition,breakdown voltage,reanodization
更新于2025-09-04 15:30:14