Influence of Cu-ion doping in NiO NPs and their structural, morphological, optical and magnetic behaviors for optoelectronic devices and magnetic applications

NiO and Cu-ion doped NiO nanoparticles with various concentrations (0.01-0.04 M) have been effectively synthesized in the current investigation using chemical precipitation method. The following techniques were used to characterized the materials' structural, morphological, elemental analysis, functional group, optical and magnetic properties: XRD, TEM, HR-TEM, SAED, SEM, EDX, FTIR, UV, PL and VSM. According to this Scherrer formula, the average crystalline sizes of the materials of pure NiO and Cu-doped NiO were determined to be 16.37 nm, 15.21 nm, 14.88 nm, 18.35 nm, and 10.88 nm, respectively. The HR-TEM images revealed that the d-spacing values about 0.24 nm, which coincides with the (111) plane of cubic NiO for pure and copper doped NiO nanoparticles. The SEM micrographs of Cu-doped NiO nanomaterials shows tiny agglomerated particles, while that of pure NiO nanoparticles shows spherical structure. Pure NiO and Cu-doped NiO nanoparticles have band gap values of 2.32 eV, 2.29 eV, 2.24 eV, 2.22 eV, and 2.27 eV, respectively. The Cu-doped NiO nanoparticles (0.01-0.03 M) at various concentrations can significantly reduce the band gap without significantly altering the structure, making them a potential material for creating optoelectronic devices. Copper was incorporated into NiO nanoparticles, which had a significant impact on the magnetic properties and changed the material from weakly ferromagnetic to ferromagnetic. In comparison to undoped NiO nanoparticles, the saturation magnetization and coercivity values of the 0.01 M and 0.03 M of Cu-doped nanoparticles is much higher. This outcome demonstrates that such Cu-doped NiO nanoparticles have promising magnetic applications.

Rapid photocatalytic degradation of cationic organic dyes using Li-doped Ni/NiO nanocomposites and their electrochemical performance

This work reports novel bi-functional Li-doped Ni/NiO nanocomposites as potential candidates for energy storage and water treatment applications.

In situ synthesis of a 3D highly porous NiO film electrode with enhanced performance for supercapacitors

The in situ synthesis of a 3D highly porous NiO film on nickel foam has been successfully achieved through a simple hydrothermal-heat treatment strategy and the fabricated NiO electrode exhibited excellent performance for supercapacitor applications.

Perforated mesoporous NiO nanostructures for an enhanced pseudocapacitive performance with ultra-high rate capability and high energy density

The morphology of NiO (1D nanobelts and 2D nanosheets) has a significant effect on the pseudocapacitive performance. The perforated and interlinked mesoporous structure of NiO nanobelts delivered higher power and energy density than nanosheets.

Effective reduced graphene oxide sheets/hierarchical flower-like NiO composites for methanol sensing under high humidity

We report the methanol sensing performance of reduced graphene oxide/hierarchical flower-like NiO under 90% of relative humidity and relatively low-temperature.

“Two channel” photocatalytic hydrogen peroxide production using g-C3N4 coated CuO nanorod heterojunction catalysts prepared via a novel molten salt-assisted microwave process

This work reports g-C₃N₄ coated CuO nanorod catalysts with outstanding photocatalytic H₂O₂ production ability via a “two channel pathway”.

Performance of Solid-state Hybrid Energy-storage Device using Reduced Graphene-oxide Anchored Sol-gel Derived Ni/NiO Nanocomposite

The influence of (nickel nitrate/citric acid) mole ratio on the formation of sol-gel end products was examined. The formed Ni/NiO nanoparticle was anchored on to reduced graphene-oxide (rGO) by means of probe sonication. It was found that the sample obtained from the (1:1) nickel ion: citric acid (Ni²⁺: CA) mole ratio resulted in a high specific capacity of 158 C/g among all (Ni²⁺: CA) ratios examined. By anchoring Ni/NiO on to the rGO resulted in enhanced specific capacity of as high as 335 C/g along with improved cycling stability, high rate capability and Coulombic efficiency. The high conductivity and increased surface area seemed responsible for enhanced electrochemical performances of the Ni/NiO@rGO nanocomposite. A solid-state hybrid energy-storage device consisting of the Ni/NiO@rGO (NR₂) as a positive electrode and the rGO as negative electrode exhibited enhanced energy and power densities. Lighting of LED was demonstrated by using three proto-type (NR₂⁽⁺⁾|| rGO⁽⁻⁾) hybrid devices connected in series.

Electrosynthesis of a corn flake-like NiO nanostructure on nickel foam for polymer gel electrolyte-based high performance asymmetric supercapacitors

A high performance asymmetric supercapacitor was fabricated with an electrodeposited corn flake-like NiO nanostructure, activated carbon, and polymer gel.

Ni–CeO2 spherical nanostructures for magnetic and electrochemical supercapacitor applications

Ni–CeO₂ spherical nano structures prepared using microwave assisted method and a specific capacitance of 577 F g⁻¹ was achieved at 2 A g⁻¹ in 1 M KOH.

Single-Step Electrophoretic Deposition of Non-noble Metal Catalyst Layer with Low Onset Voltage for Ethanol Electro-oxidation

A single-step electrophoretic deposition (EPD) process is used to fabricate catalyst layers which consist of nickel oxide nanoparticles attached on the surface of nanographitic flakes. Magnesium ions present in the colloid charge positively the flake's surface as they attach on it and are also used to bind nanographitic flakes together. The fabricated catalyst layers showed a very low onset voltage (-0.2 V vs Ag/AgCl) in the electro-oxidation of ethanol. To clarify the occurring catalytic mechanism, we performed annealing treatment to produce samples having a different electrochemical behavior with a large onset voltage. Temperature dependence measurements of the layer conductivity pointed toward a charge transport mechanism based on hopping for the nonannealed layers, while the drift transport is observed in the annealed layers. The hopping charge transport is responsible for the appearance of the low onset voltage in ethanol electro-oxidation.

Facile synthesis of carbon–NiCoO2 composite microspheres with pitaya-type structure and their application in supercapacitors

Three-dimensional carbon–NiCoO₂ microspheres were prepared. NiCoO₂ nanoparticles were inserted into porous carbon microspheres. The composite showed high specific capacity and stable capacity retention.

Enhanced electrochemical performance of NiO by addition of sulfonated graphene for supercapacitors

Porous NiO/sGNS composites with enhanced electrochemical performances were successfully fabricated using ammonium carbamate as a precipitating agent.