Electrophoretic deposition of RGO-NiO core-shell nanostructures driven by heterocoagulation method with high electrochemical performance

Abstract

A heterocoagulation route is proposed to prepare Reduced Graphene Oxide-Nickel Oxide (RGO/NiO) hybrid structures for their application as supercapacitor electrodes. The RGO intercalation among the NiO nanoplatelets was carried out by electrostatic interactions of the synthetized particles which were previously dispersed and stabilized in aqueous media to improve the assembly between both materials forming core-shell structures. The electrophoretic deposition (EPD) was used to shape the composite onto 3D collector (Ni foams) controlling their growth and homogeneity. Electrodes were thermal treated at 325ºC during 1 h to improve the electrochemical response since the formation of ceramic necks among NiO semiconductor nanoparticles preserve the microstructural integrity avoiding the employment of binders to enhance their connectivity, while RGO contributes with the electrochemical double layer effect to step up the specific capacitance by reducing the charge transfer resistance. FESEM results confirmed that RGO nanosheets were full-covered by the NiO nanoplatelets and suggested that ~1mg of the electroactive composite homogeneously covers the Ni foam and it is the optimum among of electroactive material to avoid microstructural defects that produce ohmic drops limiting the capacitance. The electrochemical characterization of the resulting binder-free RGO/NiO electrodes was compared with the bare-NiO electrode. The hybrid composite exhibited excellent performance with a high specific capacitance of 940 Fg -1 at 2Ag -1 and a higher rate capability.

Colloidal processing and sintering of WC-based ceramics with low Ni content as sintering aid

“…As precursor for nanosized nickel synthesis, a nickel nitrate hexahydrate, (Ni(NO3)2•6H2O, 98.5% purity) provided by Sigma-Aldrich (USA), was used. As synthesised nanometric nickel particles (Figure 1.c) are plate-shaped with a width ranging between 200-300 nm and thicknesses of 20-30 nm, as previously reported [23].…”

Porous spherical NiO@NiMoO4@PPy nanoarchitectures as advanced electrochemical pseudocapacitor materials

“…Especially, nanostructured NiO has been regarded as one of hopeful candidates because of the large theoretical specific capacitance (~2584 F g À1 ), low cost and good chemical stability [21,22]. Nonetheless, the intrinsic drawbacks of the TMOs with poor electronic conductivity of the crystalline structure result in the terrible cycle performance, which impede the practical application [23]. To solve the abovementioned problem, NiO with different morphologies, such as nanowires [24], nanofibers [25], nanosheets [26], nanoflakes [27], hierarchical porous hollow spheres [28], nanotube arrays [29] has been designed to reach optimized electrochemical properties.…”

Effect of Hydrothermal Method Temperature on the Spherical Flowerlike Nanostructures NiCo(OH)4-NiO

“…At the same time, a high excitation voltage is needed to maintain high current density. Therefore, without increasing the amount of interfacial charge, the capacitance measured at high current density is much smaller than that measured at low current density [15,43,44].…”