NiO/Ni Nanowafer Aerogel Electrodes for High Performance Supercapacitors.

Transition metal oxide aerogels are a fascinating class of compounds that have received considerable attention in the last decade owing to their unique and exceptional properties, including high porosity, large surface area, and ultralow density. In this study, α-Ni(OH)2 aerogels and annealed NiO/Ni aerogels were used to design and fabricate a two-electrode supercapacitor device. The physicochemical properties of the as-synthesized aerogels were characterized through X-ray diffraction, scanning electron microscopy, transmission electron microscopy, the Brunauer-Emmett-Teller theory, and X-ray photoelectron spectroscopy studies. The annealed NiO/Ni aerogels showed a (specific capacitance of 1060 F/g) specific capacity of 422 C/g at 1 A/g current density and with good cycling stability (up to 10,000 cycles). The supercapacitor also demonstrated an energy density of 32.4 Wh/kg and power density of 1800 W/kg at a current density of 2 A/g. The specific capacitance of NiO/Ni aerogels was more than twice that of the α-Ni(OH)2 aerogels. The practical applications of the aerogel were demonstrated by fabricating a two-electrode device.

Fabrication of ultrathin CoMoO4 nanosheets modified with chitosan and their improved performance in energy storage device.

Ultrathin nanosheet-assembled cobalt molybdate (CoMoO4) with a mesoporous morphology was synthesized by a urea-assisted solution combustion route at a temperature of 400 °C. The as-prepared CoMoO4 was modified using chitosan cross-linked with glutaraldehyde (glu) and employed as a cathode material in an aqueous hybrid capacitor. The physical and electrochemical behaviour of CoMoO4 modified with chitosan and the as-prepared (chitosan free) CoMoO4 has been compared and discussed. The modified CoMoO4 exhibited excellent electrochemical performance with a specific capacitance of 135 F g(-1) at 0.6 A g(-1) and an energy density of 31 W h kg(-1). It also exhibited good cycling stability with high coulombic efficiency over 2000 cycles retaining a specific capacitance of 81 F g(-1) at 3 A g(-1), comparatively much better than that of nanostructured chitosan free CoMoO4 which yielded 17 F g(-1). The results indicated that chitosan gel strongly adheres to the molybdate moiety of CoMoO4 and increases the capacitance four-fold compared to a chitosan free material. The modified CoMoO4 electrode shows potential for high performance, and is an environmentally friendly and low-cost energy storage device.