Influence of microwave power on the preparation of NiO nanoflakes for enhanced magnetic and supercapacitor applications

Abstract

Nanoflake-structured NiO were synthesized by a microwave assisted method without the use of additives. The cubic phase of NiO nanoparticles with increasing crystalline nature for higher microwave power is ascertained by X-ray diffraction studies. Previous reports revealed that hexagonally structured β-Ni(OH)2 was completely transferred into the cubic phase of NiO around 350 °C, confirmed by using thermal analysis (TG/DTA). In our present work, the size and morphology of nanoparticles are ascertained from transmission electron microscopy (TEM) analysis. Flake-like morphology with uniform size, shape and less agglomerated structure formation is obtained for 900 and 600 W of microwave power used for the synthesis of NiO samples. The effect of microwave power used for the synthesis of NiO nanoflakes was analyzed by studying the magnetic and electrochemical behavior of NiO nanoflakes. Room temperature magnetic measurements revealed the small ferromagnetic nature of NiO nanoparticles. It was observed that the samples synthesized at higher microwave power exhibited divergence behavior below 300 K in FC and ZFC measurements, which results superparamagnetic behavior. An enhanced supercapacitor performance with higher specific capacitance values was determined for NiO nanoflake samples synthesized at (25)600 W and 900 W of microwave power.

Improved Electrochemical Performance of a ZnFe2O4 Nanoflake‐Based Supercapacitor Electrode by Using Thiocyanate‐Functionalized Ionic Liquid Electrolytes

“…Figure 1(b) shows an SEM image of the ZnFe 2 O 4 thin films, which reveals a well‐adhered and uniformly interconnected porous nanoflake‐like25 surface morphology 2 μm thick and with an average flake size of approximately 25 nm 26. These nanoflakes were grown concurrently under the influence of mechanical rotation of the substrates, which hindered attainment of an equilibrium during deposition and, thus, the growth of the thin films formed porous structures.…”

Highly Pseudocapacitive NiO Nanoflakes through Surfactant-Free Facile Microwave-Assisted Route

“…Vijayakumar et al have synthesized similar NiO nanoflakes by use of CTAB with NH 3 . Formation of alike NiO nanostructures has also been conferred by Anandha Babu et al involving NH 3 alone but with enhanced dimensions . On the other hand, NiO reported via both C 2 H 5 NO 2 and CO­(NH 2 ) 2 in reaction mixture by Jung et al have resulted in highly porous agglomerated powders with particle size below 35 nm .…”

“…have been reported to obtain NiO nanoparticles in varied morphologies. ,,,, The drives behind utterly being able to enhance the material properties (e.g., surface area and porosity) of NiO and underline the structure–property relationship between its dimensional anisotropy and charge storage characteristics for supercapacitor applications. Nevertheless, developing nanodimensional NiO as nanoflakes has been of particular interest since the flake morphology acts as a firm platform with improved surface area for better intercalation of electrolyte ions into the electrode material. ,, In other words, the flake form of NiO encourages better electroactive sites for redox reaction to take place between the electrode and electrolyte species. This leads to (a) reduction in the ion diffusion path lengths and (b) lowering in the charge-transfer resistance, which overall augment the specific capacitance of NiO nanoparticles. , However, despite several reports on characterization of NiO nanomaterial as supercapacitor electrode, so far no reports are available that discuss practical applications of NiO electrode in fabrication of a supercapacitor cell.…”

“…Recently, microwave-assisted solution combustion synthesis has evolved as a popular route for developing nanoparticles of metal oxides including NiO, serving a range of technological applications. ,, By definition, this method is a modified combustion synthesis interceded via microwave irradiation (MWI) involving an aqueous mixture of an oxidizer (e.g., metal nitrate/nitrite) and a fuel (e.g., urea, glycine, and citric acid) which ensures uniform mixing of reactants at the molecular level . In principle, the energy transfer as MWI to the reactant molecules occurs through dipole rotation and ionic conduction mechanisms which results in an instant increase in temperature.…”

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

“…However, due to the high cost of Ru, there is an urgent need for developing cheaper materials. Among the various transition metal-oxides such as MnO, FeO, CoO and NiO, the NiO has been considered as unique because of its attractive features such as good redox property, high theoretical capacity (1295 C g −1 ), relatively large abundant and hence cost less, environmental friendly, ease of synthesis and its property could be tuned by means of doping with other moieties and good stability in basic medium 12 , 13 . In addition, the performance of the NiO can be tuned by changing its morphology.…”