Co₃S₄ Nanoplate Arrays Decorated with Oxygen-Deficient CeO₂ Nanoparticles for Supercapacitor Applications

Abstract

Cobalt sulfide is favorable for supercapacitors, but its application is inhibited by the inherent slow charge transfer kinetics and poor stability in alkaline solution. Herein, zeolitic imidazole framework (ZIF)-derived Co3S4 nanoplate arrays (NPAs) decorated with CeO2 nanoparticles (NPs) grown on Ni foam have been developed. The obtained Co3S4/CeO2-NPAs display a 2D leaf-like nanoplate morphology (average thickness of nearly 230 nm) with a large amount of oxygen vacancies and exhibits remarkably boosted specific capacity/capacitance, i.e., 1155.8 C/g (2408 F/g) at 0.5 A/g with a notable rate capability (76.5% at 10 A/g), compared to Co3S4-NPAs or CeO2 NPs. More importantly, a two-electrode cell comprising the Co3S4/CeO2-NPAs and an activated carbon electrode displays a high energy density of 45.4 Wh/kg (at a power density of 850 W/kg) with decent long-term durability. Furthermore, a red light-emitting diode can be lighted up for 10 min by two charged cells, showing great prospect of Co3S4/CeO2-NPAs. The outstanding electrochemical properties of the Co3S4/CeO2-NPAs are mainly attributed to the 2D nanoplate morphology with much accessible active sites and the introduction of CeO2 NPs. The Co3S4/CeO2-rich interfaces promote electron transfer between Co3S4 and CeO2. The abundant oxygen vacancies adhere to the surface of Co3S4 and can enhance the electronic conductivity and the capture of OH–. In addition, the CeO2 layer can protect the Co3S4-NPAs from corrosion by the KOH electrolyte during the electrochemical process. Therefore, the electrode developed by this work has great potential in electrochemical applications.