Construction of carbon quantum dots embed α‐Co/Ni(OH)2 hollow nanocages with enhanced supercapacitor performance

Abstract

AbstractThe etching strategy of metal‐organic frameworks is an effective process to prepare hollow electrode materials for enhanced electrochemical performance. But the relatively low conductivity of these electrode materials limits their further application. In this work, a series of carbon quantum dots (CQDs) embedded ZIF‐67 precursors (ZIF‐67@CQDs‐X, X = 1.25, 2.50, 5.00, 7.50) are synthesized firstly. Then, by a facile and controllable chemical etching process, the CQDs doped α‐Co/Ni(OH)2 hollow nanocages (α‐Co/Ni(OH)2@CQDs‐X, X = 1.25, 2.50, 5.00, 7.50) are successfully constructed. The optimized α‐Co/Ni(OH)2@CQDs‐2.50 electrode delivers a high specific surface area (277.99 m2 g−1) and dramatically enhanced conductivity. Therefore, α‐Co/Ni(OH)2@CQDs‐2.50 electrode presents a high specific capacitance (700 C g−1, 1 A g−1), superior rate performance (550 C g−1, 10 A g−1) and excellent cycling lifespan (retaining 79.93% of initial capacitance after 10 000 cycles). Coupled with the high‐performance PPD/rGO as a negative electrode, the fabricated Co/Ni(OH)2@CQDs‐2.50//PPD/rGO device exhibits an outstanding energy density of 57.29 Wh kg−1 at the power density of 0.375 kW kg−1. It is proved that the CQDs embedding and chemical etching strategy are an effective way for constructing hollow materials with enhanced energy storage performance.