Sandwich-like Ni-Zn hydroxide nanosheets vertically aligned on reduced graphene oxide via MOF templates towards boosting supercapacitive performance

Abstract

• Hierarchical sandwich-like NiZn-OH/rGO is synthesized. • The NiZn-OH/rGO integrates the high capacity and excellent electronic conductivity. • The ingredient optimization and morphology regulation are studied. • This electrode exhibits superior supercapacitive performance. Constructing the supercapacitive materials which featured with abundant contact area and high conductivity is suitable for rapid ions/electrons transport. Herein, ultrathin Ni-Zn hydroxide nanosheets are vertically aligned on reduced graphene oxide (rGO) via MOF templates, and such sandwich-like structure is featured with abundant electrolytes-accessible contact sites. Introducing porous rGO substrate with excellent electronic conductivity can not only greatly accelerate the electron transfer between current collector and hydroxide, but also depress the agglomeration of hydroxide. Besides, heterogenous Zn element is also doped into the Ni-based hydroxide, which greatly optimizes the inherent electronic structure and conductivity of Ni-based hydroxide. Benefited from sandwich-like structure, the introduction of rGO and Zn doping, such Ni-Zn hydroxide/rGO material has harvested abundant contact sites and high conductivity. As a result, this supercapacitive material is featured with suitable capacitance (615.4C g −1 at 1 A g −1 ), appropriate stability (87.5% after 8000 cycles) and superior capacity rate property (62.3% retention at 30 A g −1 ). To well disclose the energy-storage feature of this material, a corresponding hybrid supercapacitor is manufactured, which presents a high capacity of 234.3C g −1 at 1 A g −1 , superior capacity retention (89.7% retention after 10,000 cycles) and excellent energy density (53.7 Wh kg −1 at 825.1 W kg −1 ). These fascinating results demonstrate the excellent supercapacitive performance of this Ni-Zn hydroxide/rGO material.