Urchin and sheaf-like NiCo 2 O 4 nanostructures: Synthesis and electrochemical energy storage application

Ni@NiO core/shell dendrites for ultra-long cycle life electrochemical energy storage

“…1 Nickel based materials have been identied as promising electrode materials for electrochemical energy storage devices because of their high theoretical specic capacitance ($2584 F g À1 for NiO and 2082 F g À1 for Ni(OH) 2 ), environmental friendliness and low cost. 2,3 With the aim to provide a larger reaction area and shorten ion diffusion paths, many fabrication methods including chemical precipitation, 4,5 hydrothermal synthesis, [6][7][8][9][10][11] sol-gel, 12,13 thermal oxidation [14][15][16] and anodization 17,18 have been used to produce various kinds of nickel-based nanostructures, such as amorphous Ni(OH) 2 nanoboxes, 5 Ni-Co oxide nanowires, 6,19 Ni(OH) 2 nanosheets, 7,11 NiO nanobelts, 8 nanosized rambutan-like NiO, 9 urchin-like NiCo 2 O 4 , 10 spinel nickel cobaltite aerogels, 12 NiO nanoowers, 13 NiO nanoblocks 14 and sponge-like Ni(OH) 2 -NiF 2 composites. 18 Apart from the above methods, electrodeposition has gained more and more attention because the electroactive material can be directly grown on a current collector without the need for using any binder or conducting agent.…”

Electrochemical Studies of Microwave Synthesised Bimetallic Sulfides Nanostructures As Faradaic Electrodes.

“…Two pairs of broad redox peaks were observed corresponding to reversible faradaic pseudocapacitance electrochemical behavior of the electroactive electrodes which could be attributed to redox reaction based on Co 2+ /Co 3+ , Co 3+ /Co 4+ and Ni 2+ /Ni 3+ [29]. The anodic peaks shift to higher potential while the cathodic peaks shift to lower potential as the scan rate is increased probably because of kinetic in the redox process due to polarization and ohmic resistance during faradaic reactions [19,26]. Also, the shift to higher potential with increasing scan rate could be an indication of diffusion control reaction kinetics taking place during the electrochemical process.…”

“…Compared to single and simple metal oxides, mixed metal oxides or sulfides exhibit variable oxidation state, high electrical conductivity due to lower activation energy for electron transfer between cations [18][19][20]. Among the different nanostructured mixed metal oxides, Ni x Co y S 4 is considered as a promising electrode material because of its lowcost, environmentally benign nature, good electronic conductivity, high theoretical capacitance and rich electrochemical activity (redox reaction) [21].…”

NiCo2O4/rGO hybrid nanostructures for efficient electrocatalytic oxygen evolution

“…The weight loss observed at 340 and 350°C is essentially related to the formation of NiCo 2 O 4 /rGO from corresponding precursors. The third weight loss observed at above 750°C is due to the decomposition of spinel NiCo 2 O 4 into corresponding NiO and CoO [51]. The crystallographic structure and phase purity of the synthesized samples are determined by powder XRD analysis.…”

“…The D-band at 1336 cm −1 is due to the defects and disorderness in the hexagonal graphitic carbon layers [44,49]. The G-band at 1591 cm −1 is related to the vibration of sp 2 -bonded carbon atoms in a two-dimensional hexagonal lattice [40,48,51].…”