Reduced graphene oxide/Ni1−xCoxAl-layered double hydroxide composites: preparation and high supercapacitor performance

Abstract

Reduced graphene oxide (rGO) sheet and ternary-component Ni_1−xCo_xAl-layered double hydroxide (Ni_1−xCo_xAl-LDH) hybrid composites with an interesting sandwich structure have been fabricated by an in situ growth route. The as-obtained composite displays a sandwich architecture constructed by the self-assembly of sheet-like LDH crystals on both sides of the rGO sheets. It was found that the Co content doped in Ni_1−xCo_xAl-LDH plays an important role in the shape and structure of the final products. When the Co doped content is 17%, the rGO/Ni_0.83Co_0.17Al-LDH has a high surface area (171.5 m² g⁻¹) and exhibits a perfect sandwich structure. In addition, this structure and morphology is favorable for a supercapacitor electrode material with a high performance. The influence of cobalt content on the electrochemical behavior of rGO/Ni_1−xCo_xAl-LDH has been systematically studied. The results indicate that the rGO/Ni_0.83Co_0.17Al-LDH composite exhibits the highest electrochemical performance, with a specific capacitance of 1902 F g⁻¹ at 1 A g⁻¹, and an excellent cycling stability. The markedly improved electrochemical performance is superior to undoped rGO/NiAl-LDH and can be attributed to the enhanced conductivity achieved through cobalt doping. Such composites could be used as a type of potential energy storage/conversion material for supercapacitors.