Influence Of Ni Concentration Research Articles

Influence of Ni concentration on α-MnO2 catalyst support and its potential application for benzene hydrogenation to cyclohexane

Herein, we report the influence of Ni at different concentrations on manganese oxide catalyst support (Ni/α-MnO2) prepared by the combined wet-impregnation and chemical reduction methods. A correlated dependence of Ni concentration was observed on the structural, surface, and morphological properties of the catalyst. The catalytic activity of Ni/α-MnO2 was evaluated for benzene hydrogenation to cyclohexane. Ni/α-MnO2 shows superior catalytic activity, and benzene conversion efficiency achieves 96.1%, which is 2.4 times greater compared to α-MnO2. Interestingly, high Ni species concentration on α-MnO2 results in an increased benzene conversion percentage. The result is synergistically attributed to the highly dispersed Ni species on the surface of α-MnO2, increased acidity, and the improved pore diameter of the Ni/α-MnO2. This work provides a facile and convenient method to develop α-MnO2 doped by Ni at various concentrations for enhanced catalytic performance as an alternative strategy to cope with the presence of aromatic compounds in fossil fuels.

Influence of Ni concentration on the electrochemical activity and stability of ATO-based electrodes

Antimony doped tin (IV) oxide (ATO) has emerged as an acceptable electrode material for wastewater treatment due to its low cost and excellent electrochemical activity toward organics oxidation. However, achieving high electrochemical stability remains a grand challenge. Based on this fact, it is necessary to find a feasible method to prepare a novel ATO-based electrode that remains stable in the electrochemical oxidation process (EOP). In this work, we introduced NiO as a modifier material to prolong the service lifetime without losing its electrochemical oxidation performance. The effects of Ni concentration in TiO2@ATO@NiO (TAN-x, x = 0.2, 0.4, 0.6, 0.8, and 1.0) electrodes on the oxygen evolution potential (OEP), service lifetime, and electrochemical performance for degrading methylene blue (MB) were investigated. Results demonstrated that the addition of NiO significantly improve the electrochemical activity and service lifetime. TAN-0.6 electrode exhibited better electrochemical performance and longer electrode lifetime in comparison with other counterparts. These merits coupled with the high roughness factor and voltammetric charge offer a rational strategy to develop high-quality ATO-based electrodes.

Variable optical properties of La0.5Sr0.5Co1-xNixO3-δ for high-temperature resistant code application

La0.5Sr0.5Co1-xNixO3-δ (x = 0, 0.1, 0.3, 0.5) ceramics were prepared via tape casting and solid state reaction process. The influence of Ni concentration on the optical properties of La0.5Sr0.5Co1-xNixO3-δ has been investigated. Results showed that the reflectance in the range of 0.3–15 μm decreased with the increment of Ni concentration, thereby causing a change in the color phase parameters and emissivity. Based on the difference in L* values and emissivity, the letters (HOT) and QR codes (NJTECH) were fabricated. The developed letters and QR codes could be identified both at room and high temperatures. Furthermore, the QR codes were read out successfully even underwent heat treatment at 1000 °C. The results in this work demonstrate a new application of La0.5Sr0.5Co1-xNixO3-δ ceramics.

The influence of Ni concentration on the structure, mechanical and tribological properties of Ni–CrSiN coatings in seawater

The impact of Ni content on the microstructure, hardness, fracture toughness and tribological properties of Ni–CrSiN coatings in seawater was investigated by using X-ray diffraction, dynamic ultra micro hardness tester and ball-on-disk tribometer. The structural analyses indicated that the Ni existed in the form of amorphous phase regardless of concentrations. The hardness of Ni–CrSiN coating maintained around 28.1 GPa at low Ni incorporation but decreased to 20.1 GPa at 10.8 at% Ni concentration. Then, owing to grain refinement, the hardness increased to 24.5 GPa at 13.9 at% Ni concentration. All coatings presented compressive stress that led to the formation of circular cracks around indentation impression. The Ni incorporation especially at high concentration was able to improve coatings toughness against circular cracks. Although the Ni incorporation had no effect in reducing the friction coefficient of CrSiN coatings in seawater, but the moderate Ni incorporation (5.2 at%) could enhance the wear resistance of CrSiN coatings in seawater due to the favorable combination of hardness and toughness.

Influence of Ni concentration on the crystallization of amorphous Si films and on the development of different Ni-silicide phases

The crystallization mechanism was the subject of the present study which reports on the structure, and the Ni-silicide formation, of Si films containing different concentrations of Ni. The films were prepared by sputtering and were analyzed by compositional and structural characterization techniques. Additional information was obtained by thermal annealing the films up to 800 °C. The experimental results indicated that, in the as-deposited form, the films are amorphous, homogeneous, and with Ni contents in the ∼0–40 at. % range. Moreover, the development of Si and/or Ni-silicide crystalline structures was susceptible to factors like the Ni concentration, the annealing temperature and the annealing process (if cumulative or not, for example).

A comprehensive study of structural and magnetic properties of sputter deposited nickel–silica thin films

► Ni nanoparticles embedded in silica matrix have been synthesized by DC/RF sputtering. ► Magnetic properties of nickel nanoparticles have been found size dependent strongly. ► Ni nanoparticles are found to be superparamagnetic ≤6 nm. ► Coercivity decreases with increase in particle size and concentration. The present work reports the formation of Ni nanoparticles inside the SiO 2 matrix and deals with the influence of Ni concentration on structural and magnetic properties of Ni–SiO 2 nanocomposite thin films. The films with varying Ni concentration (20–55 at% measured by Rutherford back scattering spectroscopy) were deposited using DC/RF magnetron co-sputtering. TEM and XRD analysis reveal the formation of FCC Ni nanoparticles in all the samples. The particle size varies from 3 to 10 nm as a function of Ni concentration. The surface roughness of the films is also found to increase with increase in nickel concentration. Magnetic measurements show that the Ni nanoparticles behave as superparamagnets when their size is ≤6 nm, in spite of their large volume fractions. The results show that the magnetic properties of the nanoparticles can be controlled by their size and Ni concentration in the samples.

Influence of Ni concentration and Ni3Sn4 nanoparticles on morphology of Sn-Ag-Ni solders by mechanical alloying

The mechanical alloying (MA) process was employed as an alternative method to produce the lead-free solder pastes of Sn-3.5Ag-xNi (x=0.1, 0.5, 1.0, 1.5, and 2.0) in this study. When the Ni concentration was low (x=0.1, 0.5), MA particles agglomerated to a flat ingot with particle sizes >100 µm. For higher Ni concentration (x=1.0, 1.5, and 2.0), MA particles turned into fragments with particle sizes <100 µm. The particle size of the solders appeared to be dependent on the Ni concentration. To reduce the particle size of SnAgNi alloys with low Ni concentration, Ni3Sn4 nanoparticles were doped into Sn and Ag powders to derive a Ni3Sn4-doped solder. For the Ni3Sn4-doped solder, the particle size was smaller than that doped by the pure Ni. The distinction of milling mechanism between Ni3Sn4-doped solder and the pure Ni-doped solder by MA process was probed and discussed. In addition, differential scanning calorimetry (DSC) results ensured its feasibility in applying the solder material in the reflow process. Wettability tests between solders and Cu substrate also revealed that the wetting angles for Ni3Sn4-doped solder with low Ni concentration (0.1 and 0.5 wt.%) were smaller than those for pure Ni-doped solder. The wetting angles on both Cu substrate and electroplated Ni metallization for SnAgNi solders were also comparable with commercial Sn-3.5Ag and Sn-3.0Ag-0.5Cu solders. Favorable wettability of the as-derived solder in this study was clearly demonstrated.

Influence of Ni-concentration on the magnetic structure in Tb(Cu, Ni)2 system

A powder sample of orthorhombic Tb(Cu0.7Ni0.3)2 has been studied by neutron diffraction at T = 4.2 K and above the Curie temperature. It is found that this compound is ferromagnetically ordered at 4.2 K. The magnetic moment of Tb in this compound is (9.2 ± 0.2)μB, with components (2.2 ± 0.2, 0, 8.9 ± 0.1)μB. The influence of the Ni-concentration on the magnetic structure is discussed in the whole Tb(Cu, Ni)2 system.

Photoelectrochemical behavior of iron oxides thermally grown on FeNi alloys

The current—potential characteristics in dark and light for iron oxides grown thermally on FeNi alloys were determined. The influence of Ni concentration and oxidation conditions on the anodic photoelectrochemical behavior of the electrodes in 1 M KOH (pH = 13.5) is reported. The best performance characteristics were found for the photoelectrochemical cell containing as photoanode a 44% NiFe alloy mildly oxidated (90 min at 623 K).