B. Saravanakumar

Hydrothermal synthesis of spherical NiCO 2 O 4 nanoparticles as a positive electrode for pseudocapacitor applications

Hydrothermal method was adapted to synthesis NiCo2O4 nanoparticles by varying nickel and cobalt precursor concentration as 1:1, 1:2, and 1:3 ratios. X-ray diffraction (XRD) results revealed the spinel NiCo2O4 structure belongs to

Hexamine Role on Pseudocapacitive Behaviour of Cobalt Oxide (Co3O4) Nanopowders

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Zinc oxide nanotips growth by controlling vapor deposition on substrates

Fd3¯m space group system with face-centered cubic crystal structure. Raman characteristic peaks observed at 495 and 654 cm−1 explored Eg and A2g modes of spinel NiCo2O4 product. Photoluminescence (PL) results revealed the hole recombination of Ni2+/Co2+ ions from 3d-Eg and 3d-Tg electronic state of spinel NiCo2O4 material. The characteristic Fourier transform infrared spectroscopy (FTIR) metal–oxygen bands appeared at 658 and 558 cm−1 revealed the spinel-type crystal structure. SEM image revealed the NiCo2O4 spherical nanoparticles formation with an average particle size of around 500 nm. The cyclic voltammetry studies revealed the estimated average specific capacitance value of NC3 (NiCo2O4 spherical nanoparticles) as 542 F g−1 relatively higher than NC1 and NC2. The electro impendence spectroscopy results explored the small arc formation in high frequency range and very low charge transfer resistance (Rct), which resulted high conductive active materials. The estimated specific capacitance for NC3 exhibited superior galvanstatic charging and discharging (GCD) characteristics with high specific capacitance of 294 F g−1 at high current density of 1 A g−1 and revealed that the obtained electrode is suitable for supercapacitor applications.Graphical abstractHydrothermal synthesis using an excess of Co source leads to smaller and more uniform particle size. This particle size and the slightly larger crystallite size formed in the materials leads to the improved electrochemical performance of the particles.

Morphology dependent electrochemical capacitor performance of NiMoO4 nanoparticles

Nickel oxide (NiO) nanopowders were synthesized without using surfactant by chemical reduction technique. NaBH4 influence on structural, optical and magnetic properties of NiO product was investigated. XRD results revealed the formation of dominant single phase, cubic face centered nickel oxide. Raman peaks depicts the characteristic first-order transverse optical (TO) phonon, two phonon excitation (TO + LO), excitation (2LO) Raman mode vibrations of face centered cubic NiO. PL studies revealed the presence of strong emission band which is in good agreement with the intrinsic NiO product. FTIR studies explored metal oxygen vibrations of the obtained product. TEM results revealed the nanoscale product with spherical shape structures. VSM studies explored weak ferromagnetic behavior of the obtained product. High concentration of NaBH4 increases magnetization value and exhibits the typical weak ferromagnetic curve. Reducing agent played a vital role in the structural, optical and magnetic properties of the obtained NiO product.

Influence of reducing agent concentration on the structure, morphology and ferromagnetic properties of hematite (α-Fe2O3) nanoparticles

Influence of hexamine surfactant concentration on crystallite size, structure, morphology, vibrational and optical properties of cobalt oxide nanopowders were explored. The cobalt oxide nanopowders were synthesized by employing a simple chemical reduction method using cobalt (II) nitrate hexahydrate (Co(NO3)2 ·6H2O) as precursor and sodium borohydride (NaBH4) as reducing agent along with hexamine as surfactant. XRD studies revealed the formation of face-centered cubic (Fd3m) crystalline structure of Co3O4 with an average crystallite size of 8-18 nm. The observed prominent characteristic Raman active modes of A1g, Eg, and F2g revealed the formation of Co3O4 nanopowders. The optical properties of Co3O4 nanopowders are examined by photoluminescence spectra. The obtained IR results confirmed the formation of Co3O4 nanopowders. The band observed 569 cm-1 is the characteristic of the Co3+ ions in the octahedral hole vibration and the 665 cm-1 band is attributable to the Co2+ ions in the tetrahedral hole vibration in the cubic lattice. The estimated specific capacitance of the obtained Co3O4 nanopowders was 291 F/g at 10 mV/s which could be a potential candidate for pseudo capacitive nature of the active materials.

Surfactant effect on synthesis and electrochemical properties of nickel-doped magnesium oxide (Ni–MgO) for supercapacitor applications

AbstractZinc doped tin oxide nanoparticles were synthesized by employing sol–gel method assisted with different surfactants namely cetyl trimethyl ammonium bromide (CTAB), hexamine and polyethylene glycol 400 (PEG-400). The synthesis of uniform distribution of spherical Zn-SnO2 nanoparticles in presence of PEG-400 was optimized. The synthesized Zn-SnO2 nanoparticles were characterized by employing standard characterization techniques. X-ray diffraction results confirmed the product high-quality crystalline formation. The photoluminescence peaks appeared at 360 nm revealed the recombination of electron and hole from band to band emission of SnO2 optical properties. The vibrational properties of Zn-SnO2 nanoparticles were confirmed by both Raman and infra red spectra. The spherical morphology and nano sized product was evident in 200 nm scale SEM images. The cyclic voltammetry result of the product Zn-SnO2 assisted PEG-400 exhibited the specific capacitance value of 312.7 F/g at scan rate of 10 mV/s and revealed the superior electrochemical properties. Moreover, the EIS and GCD studies also revealed the good supercapacitor nature with specific capacitance of 132.1 F/g at current density of 1 A/g for the product Zn-SnO2 (PEG-400). Diagrammatic representation of Zn doped SnO2 synthesis by sol-gel method with enhanced specific capacitance of 132.1 F/g at 1 A/g for Zn-SnO2 (PEG-400).HighlightsZn-SnO2 nanoparticles in presence of PEG-400 was optimizedZn-SnO2 (PEG-400) nanoparticles exhibits superior electrochemical propertiesProduct exhibits good capacitance (132.1 F/g) at 1 A/g current density

Electrochemical characterization of FeMnO3 microspheres as potential material for energy storage applications

ZnO nanotips structure fabrication was undertaken through controlled growth by chemical vapor deposition (CVD) method. Substrate position and deposition time role was investigated systematically by controlling the parameters such as temperature, flow rate, and growth pressure. The obtained result showed that ZnO nanorods undergo a sharp regrowth process with increase in ZnO vapor availability in the CVD reactor. The surface morphology and structural properties were investigated by using field-emission scanning electron microscopy and X-ray diffraction (XRD) techniques. The grown nanostructures were used for gas sensor fabrication to detect and to study the sensitivity effects of H2 and CO.