Heterostructure of metal-organic framework-derived straw-bundle-like CeO2 decorated with (Ni, Co)3S4 nanosheets for high-performance supercapacitor

Rational design of complex nanostructure with controllable composition and morphology is highly desired for electrode materials of supercapacitors (SCs). Herein, (Ni, Co)(3)S-4 nanosheets have been decorated on metal--organic framework (MOF)-derived straw-bundle-like CeO2 assembled by one-dimensional (1D) nanorods to form a CeO2@(Ni, Co)(3)S-4 heterostructure. Such a heterostructure shows a high specific capacitance of 1319F/g at a current density of 1 A/g and an outstanding rate performance (85.2%) when the current density is increased to 10 A/g. In addition, the CeO2@(Ni, Co)(3)S-4 is assembled into an asymmetric cell, which displays a maximum energy density of 34.2 Wh/kg at a power density of 849.2 W/kg along with excellent cycling stability (84.8% of initial capacitance is retained after 10,000 cycles). The outstanding electrochemical performance of the electrode material is ascribed to the merits of CeO2@(Ni, Co)(3)S-4 heterostructure. The MOF-derived porous 1D CeO2 nanorods can afford large accessible electroactive surface area and rapid electron transfer pathways. The strong electronic interaction between CeO2 and (Ni, Co)(3)S-4 promotes surface reaction kinetics, and the abundant oxygen vacancies increase electronic conductivity of electrode and OH-capture. The rich valence states boost the specific capacitance by complex redox reactions. Besides, the core-shelled structure ensures robust mechanic stability. The present synthesis strategy can be used to prepare various heterostructures as electrode materials for SCs and electrolysis.

Automated summary

In this study, a heterostructure of CeO2@(Ni, Co)(3)S-4 was synthesized by assembling one-dimensional nanorods and nanosheets derived from a metal-organic framework (MOF). The CeO2@(Ni, Co)(3)S-4 heterostructure exhibited a high specific capacitance, outstanding rate performance, and excellent cycling stability. The impressive electrochemical performance of the electrode material can be attributed to the large electroactive surface area and rapid electron transfer pathways provided by the CeO2 nanorods, the strong electronic interaction between CeO2 and (Ni, Co)(3)S-4, the abundant oxygen vacancies promoting electronic conductivity and OH-capture, and the robust mechanic stability of the core-shelled structure.