The Preparation of Hierarchical Flowerlike NiO/Reduced Graphene Oxide Composites for High Performance Supercapacitor Applications

Abstract

Reduced graphene oxide (rGO) and NiO composites were prepared with an environmentally friendly method, in which hydrogen gas was employed as the reducing agent to convert reduced graphene oxides. Our study indicates that the success of this new approach is because NiO not only is an additive of the composites but also acts as a catalyst to facilitate the reduction. Characterization with scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and X-ray powder diffraction illustrates that the as-prepared rGO/NiO composites have a three-dimensional flowerlike hierarchical structure, which prevents graphene from taking face to face aggregation and therefore greatly improves the stability of the composite materials. A hybrid capacitor electrode made of the NiO/rGO composites shows great performance, in which the maximum specific capacitance is close to 428 F g–1 at a discharge current density of 0.38 A g–1 in a 6.0 M KOH electrolyte.

Hybrids of NiCo 2 O 4 nanorods and nanobundles with graphene as promising electrode materials for supercapacitors

“…These encouraging characteristics provide such new materials a wide range of potential applications [11,16]. Recently, numerous works have been done on hybrid metal oxides-reduced graphite oxide (RGO), such as Mn 3 O 4 , Co 3 O 4 , NiO, Fe 2 O 3 , and NiAl-LDH [17][18][19][20][21][22]. However, spinel transition metal oxides (AB 2 O 4 ), with two metal elements provide the feasibility to tune the energy density and working voltage by varying the metal content, have less been developed [23][24][25] …”

Application of GO in Energy Conversion and Storage

“…The nickel oxides/RGO composites also possess superior electrochemical performance as SC electrodes [186][187][188]. A 3-D flower-like hierarchical NiO/RGO composite has been fabricated for supercapacitor applications, in which the NiO NPs not only inhibit the RGO restacking but also function as catalyst for the GO reduction [187].…”

“…A 3-D flower-like hierarchical NiO/RGO composite has been fabricated for supercapacitor applications, in which the NiO NPs not only inhibit the RGO restacking but also function as catalyst for the GO reduction [187]. The hybrid composite electrode endows great supercapacitor performance, that is, a maximum specific capacitance up to 428 F g −1 at a discharge current density of 0.38 A g −1 in a 6.0 M KOH electrolyte is achieved.…”

Nickel oxide grown on carbon nanotubes/carbon fiber paper by electrodeposition as flexible electrode for high-performance supercapacitors

“…Among transition metal oxides, nickel oxide (NiO) has attracted much attention for its natural abundance, low cost, environmental friendliness and high theoretical specific capacitance (SC) of 2583 F g -1 [9][10][11]. Unfortunately, its intrinsically poor electrical conductivity (*10 -4 S cm -1 ) results in its practical SC and cycling stability far below theoretical value.…”