Co₃S₄ Nanoplate Arrays Decorated\nwith Oxygen-Deficient CeO₂ Nanoparticles for Supercapacitor\nApplications

Abstract

Cobalt\nsulfide is favorable for supercapacitors, but its application\nis inhibited by the inherent slow charge transfer kinetics and poor\nstability in alkaline solution. Herein, zeolitic imidazole framework\n(ZIF)-derived Co₃S₄ nanoplate arrays (NPAs)\ndecorated with CeO₂ nanoparticles (NPs) grown on Ni foam\nhave been developed. The obtained Co₃S₄/CeO₂-NPAs display a 2D leaf-like nanoplate morphology (average\nthickness of nearly 230 nm) with a large amount of oxygen vacancies\nand exhibits remarkably boosted specific capacity/capacitance, i.e.,\n1155.8 C/g (2408 F/g) at 0.5 A/g with a notable rate capability (76.5%\nat 10 A/g), compared to Co₃S₄-NPAs or CeO₂ NPs. More importantly, a two-electrode cell comprising the\nCo₃S₄/CeO₂-NPAs and an activated\ncarbon electrode displays a high energy density of 45.4 Wh/kg (at\na power density of 850 W/kg) with decent long-term durability. Furthermore,\na red light-emitting diode can be lighted up for 10 min by two charged\ncells, showing great prospect of Co₃S₄/CeO₂-NPAs. The outstanding electrochemical properties of the Co₃S₄/CeO₂-NPAs are mainly attributed to\nthe 2D nanoplate morphology with much accessible active sites and\nthe introduction of CeO₂ NPs. The Co₃S₄/CeO₂-rich interfaces promote electron transfer between\nCo₃S₄ and CeO₂. The abundant oxygen\nvacancies adhere to the surface of Co₃S₄ and\ncan enhance the electronic conductivity and the capture of OH^–. In addition, the CeO₂ layer can protect\nthe Co₃S₄-NPAs from corrosion by the KOH electrolyte\nduring the electrochemical process. Therefore, the electrode developed\nby this work has great potential in electrochemical applications.