Regulating the flower-like NiCo2S4/Zn0.76Co0.24S heterojunction through microwave heating for supercapacitors with superior cycling performance

Rationally modulating high-performance electrode materials for energy storage through an efficient and economical technology is important, and microwave is an efficient heating process utilizing dipolar polarization. Herein, we regulate high-performance NiCo2S4/Zn0.76Co0.24S (ZNCS) heterojunction materials through microwave heating. With the appropriate introduction of Zn0.76Co0.24S, the microstructure, porosity, and conductibility of original NiCo2S4 can be improved due to the regulation of heterojunction structure. Density functional theory calculations also reveal that work function induced the Schottky barrier, which can capture extra electrons at the interface and enhance redox activity. ZNCS with specific composition exhibits a high specific capacity of 692.6 C g−1 at 1 A g−1, remaining 82 % of the initial capacity as the current density increases to 20 A g−1 with excellent rate performance. A hybrid supercapacitor based on ZNCS and graphene can provide a high energy density of 57.7 Wh kg−1 (at 0.4 kW kg−1) as well as long cycle stability (87.9 % capacity retention after 20,000 cycles). This work provides a desirable, green chemistry routine (microwave process) for modulating high-performance electrode materials.