CeO2 decorated on Co-ZIF-L-derived nickel–cobalt sulfide hollow nanosheet arrays for high-performance supercapacitors

Abstract

Transition metal sulfides have been widely explored as electrode materials for supercapacitors. Unfortunately, the slow redox reaction kinetics and severe volume changes during charge/discharge result in compromised electrochemical performance. In this work, a nickel–cobalt sulfide hollow nanosheet array decorated with cerium oxide nanoparticles (NiCoS/CeO₂) has been constructed using a cobalt zeolitic imidazolate framework-L as the template coupled with subsequent solvothermal synthesis. Benefiting from the advantages of the hollow and hierarchical NiCoS nanosheets with a large number of accessible active sites and fast charge transport pathways, as well as CeO₂ layers with rich oxygen vacancies and strong interaction between NiCoS and CeO₂, NiCoS/CeO₂ exhibits a high specific capacity of 1278.1 C g⁻¹ (1 A g⁻¹), which is approximately 1.9 times that of NiCoS. The asymmetric supercapacitor assembled using NiCoS/CeO₂ and activated carbon shows an excellent storage capability (34.9 W h kg⁻¹ at 850.0 W kg⁻¹) and an impressive cycle life (91.9% capacitance retention after 10 000 charge and discharge cycles at 10 A g⁻¹).