NiO nanomaterial was synthesized at different calcination temperatures using cetyltrimethyl ammonium bromide (CTAB) as surfactant via microwave method. Thermogravimetric studies revealed the decomposition details of Ni(OH)2 precursor. The structure and morphology of the NiO was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). NiO calcined at 300 °C shows a nanoflake-like structure. A possible formation mechanism has been discussed with time evolution study. Electrochemical studies indicate that the sample calcined at 300 °C exhibits better charge storage. The NiO nanoflakes exhibit maximum specific capacitance of 401 F g(-1) at a current density of 0.5 mA cm(-2). The energy generated and hence the charges collected from wind and solar panels are slow but in many applications the power delivery has to be at a faster rate. Considering this aspect, slow-charge and fast-discharge tests have been performed and reported. The NiO nanoflakes appear to be a promising electrode material for supercapacitor application.

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Via the green chemistry route, Mn3O4/amorphous carbon nanoparticles have been synthesized. Dextrose was used as the reducing agent, and starch was used as the capping agent. The X-ray diffraction patterns reveal the Hausmannite tetragonal structure of the synthesized Mn3O4 particles. EDAX analysis confirms the presence of carbon and stoichiometry of Mn3O4. Morphological studies reveal the nanospherical nature of the synthesized particles. The FTIR spectra confirm the presence of Mn–O bonds. Mn3O4/AC 500 exhibits highest specific capacitance of 522 F g–1 at a specific current of 1 A g–1, when measured from the charge–discharge process. This value is superior to previous reports on Mn3O4 nanoparticles as an electrode for supercapacitors. Higher energy density of 58.72 W h kg–1 could be observed for Mn3O4/AC 500, which is higher than lead acid batteries and comparable to those for the nickel hydride batteries. These results indicate that Mn3O4/AC 500 is a promising electrode for supercapacitor applications.

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Noble gold nanoparticles (AuNps) are generally nontoxic due to their inert nature. The gold nanoparticles are easily tagged with various proteins and biomolecules rich in aminoacid leading to important biomedical applications including targeted drug delivery, cellular imaging, and biosensing. In this study, three cytotoxicity detection assays 3-(4,5-dimethylthiozol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), neutral red cell, and lactate dehydrogenase (LDH) on gold nanoparticles stabilized with citrate, starch, and gum arabic are used. The assays used are based on different mode of detection like LDH release, MTT metabolism, and neutral red uptake. We found that the AuNps stabilized with citrate are very sensitive to the change of concentration and time assay compared to starch and gum arabic stabilized gold nanoparticles.