Interface engineered Zn/Co-S@CeO2 heterostructured nanosheet arrays as efficient electrodes for supercapacitors

Bimetallic sulfides with superior electrochemical activity are extensively explored as electrode materials for electrochemical energy related applications. However, their utilizations are impeded due to unfavorable faradaic reaction kinetics and poor electrochemical stability. To overcome these defects, this study reports interface engineering of heterogeneous nanosheet arrays on Ni foam (NF) through surface modification of metal-organic framework (MOF)-derived zinc cobalt sulfide (Zn/Co-S) with CeO2 nanoparticles (NPs). MOF-derived porous Zn/Co-S nanosheets have highly exposed electrochemical active sites and abundant channels for charge transport. The strong interfacial coupling between Zn/Co-S and defective CeO2 leads to fast charge transfer, thereby improving electrochemical activity. The CeO2 can also prevent Zn/Co-S from degrading in KOH solution. Moreover, the self-supported electrode shows high electronic conductivity and strong adhesion with the conductive substrate. Therefore, the specific capacity and electrochemical stability of resulting Zn/Co-S@CeO2/NF are significantly higher compared with Zn/Co-S/NF. Furthermore, an asymmetric supercapacitor (ASC) based on Zn/Co-S@CeO2/NF and activated carbon (AC) exhibits high energy storage capability (42.4 Wh kg−1) and outstanding operating durability (91.1 % after 8000 cycles). These results demonstrate that the as-prepared electrode is a superior candidate for electrochemical devices.