Ni Doping Research Articles

Enhancing the performance of CuO thin film in solar cell by introducing optimum amount of Ni doping

Enhancing the performance of CuO thin film in solar cell by introducing optimum amount of Ni doping

Effect of Ni doping on the microstructure and electrical properties of Ba–Co–O NTC ceramics

Effect of Ni doping on the microstructure and electrical properties of Ba–Co–O NTC ceramics

Synthesis and Characterization of Perovskite Manganate Based on La0.7Ca0.3MnO3 with Ni and Ti doping as Microwave Absorber Material

Research has been carried out on the effect of Ni and Ti doping on the microwave absorption properties of the perovskite manganate material La0.7Ca0.3Mn1-xNix/2Tix/2O3 (LCMNTO) with variations x = 0; 0.03; 0.05; and 0.1, which were synthesized by the sol-gel method. The effect of Ni and Ti doping on the structure, grain size, magnetic properties, and microwave absorption properties were investigated in detail by various analytical methods. XRD (x-ray diffraction) characterization showed that the material La0.7Ca0.3Mn1-xNix/2Tix/2O3 has a single phase with an orthorhombic crystal system. The SEM (scanning electron microscope) results showed a tendency to decrease in grain size when the composition of Ni and Ti dopants began to increase. VSM (vibrating sample magnetometer) characterization shows that La0.7Ca0.3Mn1-xNix/2Tix/2O3 is a soft magnet with magnetic properties that decrease with increasing Ni and Ti dopant composition. The characterization of VNA (vector network analyzer) in the 8-12 GHz shows that the highest ability to absorb microwaves is 98% at 8.24 GHz, and there is an addition of absorption areas point and widening of the absorption bandwidth. Thus, the material La0.7Ca0.3Mn1-xNix/2Tix/2O3 has the potential to become a microwave absorber material.

Enhancement of structural, optical, electrical, optoelectronic and thermoelectric properties of ZnO thin film via Ni doping and Ni-B co-doping

In this study, the effects of nickel (Ni) and boron (B) elements on the structural, optical, electrical, optoelectronic, and thermoelectric properties of zinc oxide (ZnO) material were investigated. Therefore, undoped ZnO, 3% Ni-doped ZnO (Zn0.97Ni0.03O), and 3% Ni-1% B co-doped ZnO (Zn0.96Ni0.03B0.01O) solutions were prepared by the sol gel method. The produced solutions were coated on glass and p-type Si substrates via dip coating and spraying methods in the form of thin films. We produce pure and n-type semiconductors in the form of nanodots which have wurtzite ZnO polycrystalline structure for all samples. Ni and B co-doped sample is morphologically, electrically and optically enhanced the ZnO material with 3.08 eV band gap, homogenous surface and the highest electrical conductivity. In addition, the best material among the three samples that can be used as a visible light-sensitive sensor is Zn0.96Ni0.03B0.01O under feedback voltage. Technologically, this material can be turned into a photodiode device in the form of Au/Zn0.96Ni0.03B0.01O/p-Si. While the obtained ideality factor of ZnO from the forward bias region decreases from 5.7 to 3.4, its barrier height increases from 0.636 eV to 0.667 eV and serial resistance of contact decreases from 121.6 × 103 Ω to 5.6 × 103 Ω with Ni and B co-doping. Ni doping thin film improves the photovoltaic, and thermoelectric properties of ZnO. Ni-doped ZnO sample can be studied in form of the thin films as a thermoelectric material due to its ZT value is nearly 1.73 × 10–4 at 650 K. Its thermoelectric performance is 13 times better than the that of pure ZnO for the same temperature values. The efficiency of Ni-doped ZnO sample as solar cell increases 10 times compared to pure ZnO. In addition to the production of materials with improved energy efficiency, economical products suitable for use in large areas have been obtained in this study.

Role of outer shell electron-nuclear distant of transition metal atoms (TMA) on band gap reduction and optical properties of TiO2 semiconductor

The reduction of the band gap of titanium dioxide (TiO2) via transition metal atoms (TMAs) is the focus of many research groups to increase its absorption to visible region of electromagnetic (EM) radiation. In this modeling it was shown that atoms having near outer electron shells affect strongly on the band gap of TiO2. The TiO2 has exceptional photoactivity, high stability, and cost-effectiveness. The results of the current study emphasized that adjustable TiO2 photocatalyst material can be produced through band gap reduction by Pt, Pd, and Ni dopants. The electronic configurations and optical properties of both undoped and (Ni, Pd and Pt)-doped TiO2 have been studied using first-principles calculations within the framework of Density Functional Theory (DFT) with the aid of the Vienna Ab initio Simulation Package (VASP). The role of electronegativity of TMAs on band gap drop was discussed for the first time. The band gap of clean TiO2 was found to be 3.2 eV using the band structure (BS) and Tauq model. The results indicate that Ni TMA with lowest electronegativity reduces the band gap of TiO2 to the lowest value (0.86 eV). The results of BS and density of state revealed the fact that small outer shell electron-nuclear distant TMA more affected the band gap of TiO2. The band gap determined from the imaginary part of the optical dielectric function closely aligns with those determined from the BS diagram. The increase in the refractive index (n) was observed with the increase of Ni, Pd, and Pt into the TiO2 structure, which indicates an increase in charge density within the TiO2 structure. The reflectance, absorbance, and transmittance results suggest that Pd and Pt-doped TiO2 are responsive to the visible region of electromagnetic radiation, whereas Ni-doped TiO2 exhibits responsiveness in the IR region. In its pure state; TiO2 was found almost transparent in the visible and IR regions of EM radiation.

Effect of foreign impurity and growth temperatures on hexagonal structure and fundamental properties of ZnO nanorods.

This study examined the influence of growth temperature and dopant concentration on the properties of Gd- and Ni-doped zinc oxide nanorods (ZnO NRs). ZnO seed layers were deposited on glass substrates using a sol-gel and dip-coating approach. Gd- and Ni-doped ZnO NRs were hydrothermally grown on the seed layers at different temperatures such as 75, 90, and 105°C for a constant growth time of 5 h. The crystal structure, optical, surface morphology views, and electrical properties of the NRs were extensively investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy, and four probe experimental methods. The XRD analysis confirmed the successful substitution of Zn2+ ions by Gd3+ and Ni2+ within the ZnO main matrices. The reordering of hexagonal structures with varied electronegativity, ionic radius dimensions, and valence electron states of Gd and Ni dopants affected seriously the fundamental characteristic features of NRs. The SEM images showed that the ZnO NRs grown at 90°C possessed a more favorable surface morphology and well-defined hexagonal shape compared with those grown at other growth temperatures. Higher dopant concentration led to an increase in NR diameter but a decrease in density depending on the increase in the space between the NRs. Additionally, the optical transmittance was found to generally enhance with increasing dopant concentration. The results obtained highlighted the interplay between growth temperature, dopant type and concentration in tailoring the structural, morphological, and optical properties of Gd- and Ni-doped ZnO NRs, paving the way for the development of optimized nanomaterials for various applications. RESEARCH HIGHLIGHTS: The XRD analysis confirmed the successful substitution of Zn2+ ions by Gd3+ and Ni2+ within the ZnO main matrices. The SEM images showed that the ZnO NRs grown at 90°C possessed a more favorable surface morphology and well-defined hexagonal shape compared with those grown at other growth temperatures. The optical transmittance was found to generally enhance with increasing dopant concentration. The results obtained highlighted the interplay between growth temperature, dopant type and concentration in tailoring the structural, morphological, and optical properties of Gd- and Ni-doped ZnO NRs, paving the way for the development of optimized nanomaterials for various applications.

Improving structural and magnetic properties of zinc stannate thin films through nickel doping via sol–gel method

Ternary oxides are currently emerging as promising materials for optoelectronic devices and spintronics, surpassing binary oxides in terms of their superior properties. Among these, zinc stannate (Zn2SnO4) stands out due to its stability and attractive physical characteristics. However, despite its outstanding attributes, there is a need to further develop its magnetic properties for spintronic applications. In this study, Ni-doped Zn2SnO4 thin films were synthesized using the sol–gel method, and their magnetic characteristics were investigated for the first time. X-ray diffraction analysis confirmed the high crystallinity of the synthesized samples, even after the incorporation of Ni dopants, without any secondary phases. SEM imaging revealed the cubic structure morphology of the thin films. An increase in the bandgap, dependent on the Ni dopant concentration, was observed for doped zinc stannate, suggesting potential for tailored electronic properties. FTIR spectroscopy confirmed the presence of functional groups within the material. Notably, the magnetic properties of the thin films were analyzed using a vibrating sample magnetometer (VSM), revealing diamagnetic behavior for pure zinc stannate and ferromagnetic properties for Ni-doped Zn2SnO4, which increased with dopant concentration. Overall, the results highlight the excellent structural, optical, and ferromagnetic properties of Ni-doped Zn2SnO4 thin films, positioning them for diverse applications, particularly in optoelectronic and spintronic technology.

Ion-doped γ-C2S: Clinker characteristics, carbonation products, and carbonation properties

The γ-crystalline form of dicalcium silicate (γ-C2S) is recognized for its carbonation activity, making it a promising low-carbon binder. This study investigates how impurity ions such as sodium, magnesium, phosphorus, potassium, titanium, nickel, copper, and zinc influence the carbonation characteristics of γ-C2S. Results on the calcined γ-C2S powders indicate that Na, P and K doping hinder the β-γ phase transition. Mg, Ti, Ni and Cu doping have little effect on the crystal form of γ-C2S, but substantially alter their morphology, evident in reduced particle size and increased surface folds. This increases the specific surface area and may facilitate the carbonation reaction. Analysis on carbonation products reveals calcium carbonate content is increasing especially in calcite crystals. The results of carbonation exothermic show the elevation of maximum temperature with the doping level increases. This may be attributable to ion doping promoting the dissociation of Ca2+. The increase in degree of carbonation and compressive strength illustrates the beneficial effects of these ionic doping on mechanical and carbonation properties, in particular, Ti ion doping increased 15.6 % and 75.7 % compared to the blank group, respectively. However, Zn doping is contrary to the results of other four ions and its addition has a negative effect on the properties of γ-C2S. All five ions (Mg, Ti, Ni, Cu, Zn) can be effectively solidified into the calcium carbonate crystals of the carbonation product, which is an important guideline for the future resource utilization of waste and industrialized production. Ion doping provides a reliable reference for future modification of γ-C2S.

Electrochemical Leaching of Ni Dopants in IrRu Alloy Electrocatalyst Boosts Overall Water Splitting

AbstractThe commercialization of water‐splitting technology strongly relies on the stable and high‐performance electrocatalyst for hydrogen and oxygen evolution reactions (HER‐OER). In this work, the nickel dopants in IrRu alloyed electrocatalyst for acidic water splitting activity are investigated. The incorporation of nickel dopants induces more oxygen atoms coordinating with Ir/Ru facilitating the formation of *OOH species via nucleophilic attack by H2O. Additionally, a fast surface reconstruction is achieved due to the electrochemical dissolution of Ni dopants; as a result, more oxygen species are incorporated, evidenced by in situ Raman spectroscopy and electrochemical impedance spectroscopy. Therefore, the mass activity for Ni@IrRu is enhanced by threefold than commercial IrO2 in acidic OER catalysis. Moreover, the nickel dopants balance the hydrogen binding strength; as a result, only 609 mV overpotential is demanded to reach 1 A cm−2 in acidic HER catalysis. The polymer electrolyte membrane water electrolyzer (PEMWE) test indicates only 1.87 V is required to attain 2 A cm−2, 160 mV lower than Pt/C‐IrO2 revealing its potential application in PEMWE.

Tailoring Co site reactivity via Sr and Ni doping in LaCoO3 for enhanced water splitting performance

Perovskite oxides (ABO3) featuring rare-earth cations in the A-site and first-row transition-metal cations in the B-site, have emerged as promising catalytic materials for addressing the slow kinetics of the water splitting reaction. In this study, we synthesized La1-xSrxCo1-yNiyO3 using the solution combustion synthesis method and conducted a comprehensive investigation into the structural, surface, and electronic properties of the resulting materials. The strategic doping of Sr in La sites and Ni in Co sites has notably enhanced the kinetics and effectiveness of both the oxygen evolution reaction at the anode and the hydrogen evolution reaction at the cathode, leading to an overall improvement in water splitting efficiency over La1-xSrxCo1-yNiyO3. Detailed mechanistic studies have revealed the crucial role of high covalency and surface oxygen vacancies, tailored through aliovalent doping, in enhancing the catalytic activity of the oxygen evolution reaction in La1-xSrxCo1-yNiyO3. This research serves as a pioneering effort to establish a correlation between electronic and surface properties and to elucidate the mechanistic aspects of water splitting over perovskite materials.

Exploring the photocatalytic and photodetection potential of undoped and nickel-doped molybdenum trioxide nanoplates: Synthesis and characterization

Orthorhombic stable phase of MoO3 and Ni-doped MoO3 with different weight percentages (2 %,5 % and 10 %) were successfully synthesized by following a surfactant free acid-assisted chemical co-precipitation method under optimized experimental conditions. Structural and compositional investigation using tools like X-ray diffraction and Raman spectroscopy verified the orthorhombic phase and structure quality of the prepared samples with findings from Raman consistent with those from XRD. The optical characteristics analysed using UV–Vis diffused reflectance spectroscopy and photoluminescence spectroscopy revealed that Ni2+ may act as a shallow acceptor at lower doping concentrations. It was observed that the structure and characteristics of MoO3 dramatically altered as a function of Ni doping concentration, suggesting that Ni ions migrated from lattice substitution to grain boundaries. Images from field emission scanning electron microscope revealed the formation of layer-by-layer growth of micro-plate like morphology of the prepared samples with increasing agglomeration influenced by grain boundaries. EDAX spectrum confirmed the presence of Mo, O and Ni and their compositional proportion. Based on the properties analysed, the photocatalytic properties of the synthesized samples were analysed for degradation of Alizarin Red dye and kinetic studies were conducted. The optical characterization revealed defect induced emissions and the feasibility of MoO3 acting as a photodetector was studied along with Ni-doping proving the versatility of material for multifunctional applications.

Metal organic framework-derived porous Ni-doped In2O3 for highly sensitive and selective detection to hydrogen at low temperature

Achieving high sensitivity and selective detection at low temperature is of great significance for hydrogen leakage monitoring and early warning. As a very promising hydrogen sensitive material, In2O3 still faces great challenges in achieving high-performance hydrogen sensing at low temperatures due to inherent defects such as low specific surface area and limited active sites. Here, we prepared Ni-doped In2O3 mesoporous nanomaterials using metal organic framework (MOF) as sacrificial templates. The prepared Ni-doped In2O3 exhibited mesoporous structures with small diameters (2–3 nm), which could be used as effective molecular sieves for the selective detection of hydrogen. The high specific surface area (72.0 m²/g) provided numerous active sites for surface redox reactions, resulting in a remarkable hydrogen sensing response. Notably, gas sensitivity tests demonstrated that the Ni-doped In2O3 gas sensor achieved optimal hydrogen detection performance at 100°C. Particularly, the 3 at% Ni-doped In2O3 nanomaterials exhibited a high response of 12.5–100 ppm hydrogen, along with favorable response/recovery time and a practical limit of detection down to 5 ppm. Furthermore, the Ni-doped In2O3 sensor exhibited excellent reversibility, reproducibility, selectivity and long-term stability. In addition, simulation calculations based on molecular dynamics (MD) and density functional theory (DFT) show that molecular sieve effect is the main reason for the enhanced selectivity, and Ni doping induced oxygen vacancy (OV) defects could enhance gas adsorption. This work could provide technical support for leak detection and warning during hydrogen use, storage and transportation in the future.

Tuning of thermoelectric performance by modulating vibrational properties in Ni-doped Sb2Te3

Sb2Te3, a binary chalcogenide-based 3D topological insulator, attracts significant attention for its exceptional thermoelectric performance. We report the vibrational properties of magnetically doped Sb2Te3 thermoelectric material. Ni doping induces defect/disorder in the system and plays a positive role in engineering the thermoelectric properties through tuning the vibrational phonon modes. Synchrotron powder x-ray diffraction study confirms good crystalline quality and single-phase nature of the synthesized samples. The change in structural parameters, including B iso and strain, further corroborate with structural disorder. Detailed modification of phonon modes with doping and temperature variation is analysed from temperature-dependent Raman spectroscopic measurement. Compressive lattice strain is observed from the blue shift of Raman peaks owing to Ni incorporation in Sb site. An attempt is made to extract the lattice thermal conductivity from total thermal conductivity estimated through optothermal Raman studies. Hall concentration data support the change in temperature-dependent resistivity and thermopower. Remarkable increase in thermopower is observed after Ni doping. Simulation of the Pisarenko model, indicating the convergence of the valence band, explains the observed enhancement of thermopower in Sb2−x Ni x Te3. The energy gap between the light and heavy valence band at Γ point is found to be 30 meV (for Sb2Te3), which is reduced to 3 meV (in Sb1.98Ni0.02Te3). A significant increase in thermoelectric power factor is obtained from 715 μWm−1K−2 for pristine Sb2Te3 to 2415 μWm−1K−2 for Ni-doped Sb2Te3 sample. Finally, the thermoelectric figure of merit, ZT is found to increase by four times in Sb1.98Ni0.02Te3 than that of its pristine counterpart.

High Capacity and Fast Kinetics Enabled by Metal-Doping in Prussian Blue Analogue Cathodes for Sodium-Ion Batteries.

Prussian blue analogues (PBAs) have gained tremendous attention as promising low-cost electrochemically-tunable electrode materials, which can accommodate large Na+ ions with attractive specific capacity and charge-discharge kinetics. However, poor cycling stability caused by lattice strain and volume change remains to be improved. Herein, metal-doping strategy has been demonstrated in FeNiHCF, Na1.40Fe0.90Ni0.10[Fe(CN)6]0.85 ⋅ 1.3H2O, delivering a capacity as high as 148 mAh g-1 at 10 mA g-1. At an exceptionally high rate of 25.6 A g-1, a reversible capacity of ~55 mAh g-1 still can be obtained with a very small capacity decay rate of 0.02 % per cycle for 1000 cycles, considered one of the best among all metal-doped PBAs. This exhibits the stabilizing effect of Ni doping which enhances structural stability and long-term cyclability. In situ synchrotron X-ray diffraction reveals an extremely small (~1 %) change in unit cell parameters. The Ni substitution is found to increase the electronic conductivity and redox activity, especially at the low-spin (LS) Fe center due to inductive effect. This larger capacity contribution from LS Fe2+C6/Fe3+C6 redox couple is responsible for stable high-rate capability of FeNiHCF. The insight gained in this work may pave the way for the design of other high-performance electrode materials for sustainable sodium-ion batteries.

In-situ metal doping to boost the reactivity of layered double hydroxide derived Mg-Fe-Al-O oxygen carriers for chemical looping CH4 reforming with CO2 reduction

Employing layered double hydroxide (LDH) as a self-template to synthesize iron-based oxygen carrier is a powerful pathway to achieve efficient chemical looping CH4 reforming with CO2 reduction. However, the inevitable formation of inactive component causes a harmful effect on the reactivity. This work proposes an in-situ metal doping strategy to solve this issue. Mg-Fe-Al-O oxygen carriers with varying metal dopants (Ni, Cu, Mn, Ca) and substitution ratios (0–0.5) are examined to investigate its influence on cyclic reactivity and redox mechanism. Ni and Cu dopants enhance the reactivity whilst Mn and Ca make a worse impact. Doping Ni with a ratio of 0.5 (Mg1Ni0.5Fe0.75Al0.25) exhibits a superior reactivity: syngas space time yield (10 mmolCO·kgOC-1·s-1 and 18 mmolH2·kgOC-1·s-1) and CO space time yield (60 mmolCO·kgOC-1·s-1). This originates from: (i) Ni is segregated from solid solution to promote methane activation, and (ii) the re-oxidation of more generated iron and carbon produces more CO.

Water sensitized and highly bright multicolor Ni-doped carbon dots nanoarchitectonics in polar solvents towards stable flexible films

To address the issues of low photoluminescence quantum yields (PLQYs), broad PL spectra, and poor stability, multicolor carbon dots (CDs) were synthesized by using different precursors. Blue-emitting CDs were created via a solvothermal synthesis by using citric acid and ethylenediamine while green-emitting CDs were fabricated using O-phenylenediamine. Ni doping further increased the PLQYs and stability of CDs. Ni-doped CDs (Ni-CDs) with blue- and green-emitting were synthesized through a one-step solvothermal method. The PL peak wavelengths of Ni-doped blue CDs (Ni-BCDs) and Ni-doped green CDs (Ni-GCDs) were located at 450 and 540 nm, respectively. After Ni-doping, the average particle size of green-emitting CDs was increased from 2.35 to 2.65 nm. Compared with undoped CDs, Ni-CDs exhibited narrow PL spectra, high PLQYs, and long fluorescent lifetime. The PLQYs of Ni-BCDs and Ni-GCDs were increased to 83.92 and 35.60 %, respectively. Interestingly, the PL peak wavelengths of Ni-doped CDs revealed a red-shift with increasing the solvent polarity (e.g. acetone, acetonitrile, N, N-dimethylformamide, tetrahydrofuran, dimethyl sulfoxide, ethanol, methanol, and H2O). In addition, the PL peaks of green-emitting Ni-CDs generated a large red-shift with increase the ratio of water in organic solvents compared with blue one. Namely, solid Ni-GCDs powders also revealed water dependent PL. After incorporating the CDs in flexible films, Ni-GCDs still revealed high brightness and stability. These results supplied important possibility for the application of multicolor CDs.

Theoretical Study of the Multiferroic Properties of Ion-Doped CaBaCo4O7

Using a microscopic model and Green’s function theory, we investigated the magnetization, specific heat, and polarization properties of CaBaCo4O7 (CBCO), scrutinizing their variations with temperature, magnetic field strength, and doping effects. Our analysis revealed a conspicuous kink in the specific heat curve near the critical temperature (TC), indicative of a phase transition. Additionally, the observed increase in polarization, P with escalating magnetic field strength serves as compelling evidence for the multiferroic nature of CBCO. Substituting Co ions with Fe ions resulted in an augmentation of the CBCO magnetization, M, while doping with Zn, Mn, or Ni ions led to a decline. Similarly, doping CBCO with Y or Sr ions at the Ca site exhibited divergent effects on magnetization, M, with an increase in the former and a decrease in the latter case. This modulation of the magnetization, M, can be attributed to the varying strains induced by the doping ions, thereby altering the exchange interaction constants within the system. The polarization, P, increases by Ni, Mn, or Zn substitution on the kagome layer Co sites. It can be concluded that Ni, Mn, or Zn doping enhances the magnetoelectric effect of CBCO. Notably, our findings align qualitatively well with experimental observations, reinforcing the validity of our theoretical framework.

Effect of Ni Substituted MgZrTa2O8 Ceramics on Sintering Characteristics and Microwave Dielectric Properties

Herein, Mg1−xNixZrTa2O8 (x = 0, 0.1, 0.3, 0.5, 0.8, 1) ceramics are synthesized using a solid‐phase reaction method. Ni2+ replacing Mg2+ improves the drawback of high sintering temperature and poor temperature stability. The samples have a relative density above 95% at the optimal sintering temperature. The sintering temperature of Mg1−xNixZrTa2O8 reduces from 1475 to 1400 °C. And single‐phase Mg1−xNixZrTa2O8 ceramics with monoclinic wolframite structures are analyzed. According to the Rietveld refinement results, with the doping of Ni2+, the transformation of unit cell volume leads to the shift of the main peak in the X‐Ray diffraction pattern to a higher angle in 0 ≤ x ≤ 0.3 and a lower angle in 0.5 ≤ x ≤ 1. The εr of Mg1−xNixZrTa2O8 is comparable to MgZrTa2O8. At 1400 °C, the Q × f is increased from 10 598 GHz in the undoped sample to 43 041 GHz in Mg0.9Ni0.1ZrTa2O8 ceramic. The absolute values of τf of ceramic samples decrease with the excessive Ni2+. The desirable dielectric properties (εr = 20.79, Q × f = 43 041 GHz, τf = −33.04 ppm °C−1) are obtained at 1400 °C. Ni substitution is effective for MgZrTa2O8 ceramic to optimize densification temperature and retain the high Q × f value.

Microwave-assisted synthesis of Ni-doped europium hydroxide for photocatalytic degradation of 4-nitrophenol

Microwave-assisted synthesis method was used to prepare europium hydroxide (Eu(OH)3) and different percentages of 1, 5, and 10 % nickel-doped Eu(OH)3 (Ni–Eu(OH)3) nanorods (NRs). X-ray diffraction study showed a hexagonal phase with an average crystallite size in the range of 21 – 35 nm for Eu(OH)3 and Ni–Eu(OH)3 NRs. FT-IR and Raman studies also confirmed the synthesis of Eu(OH)3 and Ni–Eu(OH)3. The synthesized materials showed rod-like morphology with an average length and diameter between 27 – 50 nm and 8 – 13 nm, respectively. The band gap energies of Ni–Eu(OH)3 NRs were reduced (4.06 – 3.50 eV), which indicates that the doping of Ni2+ ions has influenced the band gap energy of Eu(OH)3. The PL study exhibited PL quenching with Ni doping. The photocatalytic degradation of 4-nitrophenol (4-NP) by the synthesized materials under UV light irradiation was investigated, in which 10 % Ni–Eu(OH)3 NRs showed the best response. A kinetic study was also conducted which shows pseudo-first-order kinetics. Based on this, Ni–Eu(OH)3 NRs have shown a potential to be a UV-light active material for photocatalysis.

Enhanced the electrochemical performance of Ni-doped α-MnO2 prepared with one-pot process for supercapacitors

Poor capacitive behavior caused by low electronic conductivity and slow reaction kinetics is the main obstacle faced by the MnO2 electrode materials in current supercapacitors. Herein, the influence of Ni doping on the capacitive behavior of α-MnO2 synthesized by a low-cost and one-pot chemical coprecipitation method was investigated. During the doping process, the amount of Ni was increased from 0.05 mmol to 0.45 mmol in steps of 0.1 mmol. The structure and chemical composition of Ni-doped MnO2 (MnO2-Ni) were characterized by XRD, FTIR, SEM, EDS, and XPS. Comprehensive studies show that no change in the crystal phase structure of MnO2, while the decrease in the nanoparticle size and the increase in electronic conductivity by Ni doping, which improve the capacitive behavior of α-MnO2. With specific capacitance values increasing with increasing amounts of Ni up to a certain limit 0.25 mmol, the specific capacitance of 325.8 F/g was given by MnO2-Ni electrode at a current density of 0.5 A/g, which was nearly 1.72 times that of MnO2 electrode of 189.47 F/g. Moreover, the MnO2-Ni electrode showed excellent capacitance retention (112%) than the MnO2 electrode (109.5%) after 3000 cycles.