In-situ formation of oxygen-vacancy-rich NiCo2O4/nitrogen-deficient graphitic carbon nitride hybrids for high-performance supercapacitors

Rational designing of a facile synthetic protocol for synchronously generating NiCo2O4 and conductive carbon is a great challenging for high-performance supercapacitors. Herein, a one-pot and scalable approach has been developed to in-situ construct oxygen-vacancy-rich NiCo2O4 /nitrogen-deficient graphitic carbon nitride (O-v-NiCo2O4/ND-g-C3N4) hybrids. The in-depth investigations reveal that there is an intriguing interaction between NiCo2O4 and g-C3N4, which unexpectedly enables the generating of O-v-NiCo2O4 and transforming of g-C3N4 into ND-g-C3N4 structures. Moreover, the g-C3N4 plays the skeleton and template role to form the foam-like structure. Benefiting from abundant active species and improved electrical conductivity, the resultant O-v-NiCo2O4/ND-g-C3N4 exhibits an unrivalled specific capacitance of 1998 F g(-1) (equalling 277.5 mAh g(-1)) at a current density of 2 A g(-1) and excellent rate capability (78.66% capacity retention at 20 A g(-1)). Besides, the assembled O-v-NiCo2O4/ND-g-C3N4//activated carbon asymmetric supercapacitors deliver a maximum energy density of 70.22 Wh kg(-1) at a power density of 800 W kg(-1), and a remarkable cycling stability with 95.22% retention even after 5000 cycles, outstripping most of reported NiCo2O4-based supercapacitors. Thus, this work sheds light on the developing of advanced pseudocapacitive materials for electrochemical energy storage. (C) 2020 Elsevier Ltd. All rights reserved.