Flower-like g-C3N4 nanosheets decorated hollow Co2NiO4 cube derived from ZIF-67 for excellent performance supercapacitors

Abstract

In this study, zeolite imidazole framework 67 (ZIF-67)-derived Co 2 NiO 4 cubes decorated with flower-like g-C 3 N 4 nanosheets (CN) were reported as novel electrode materials for supercapacitors with excellent capacitance and cycling stability. The prepared composite material was synthesized by a simple solvothermal method, and its structural characteristics were revealed by XRD, SEM and FT-IR spectroscopy. Moreover, cyclic voltammetry, constant current charge/discharge test and AC impedance test were used to study the electrochemical behavior of composite materials. The results showed that by combining Co 2 NiO 4 cubes with good redox reactions with flower-like g-C 3 N 4 nanosheets, adding different amounts of g-C 3 N 4 nanosheets during the reaction can effectively improve their electrochemical performance. As expected, Ni/Co-5 %CN exhibits an excellent specific capacitance of 1701 F·g −1 at 1 A·g −1 when the CN addition is 5 %. Besides, constructed asymmetric supercapacitor (Ni/Co-5 %CN//AC ACS) showed a high energy density of 49.37 Wh·kg −1 . After 5000 cycles at 5 A·g −1 , it can achieve nearly 91.5 % capacitance retention rate. The results showed that Ni/Co-CN had great potential to build safe and high-performance energy storage devices. Here, we first used ZIF-67 as a precursor to successfully synthesize Co 2 NiO 4 with a hollow cubic structure. Then, using acidified thinner graphitized carbon nitride (g-C 3 N 4 ) for decorative design, a hollow Co 2 NiO 4 /g-C 3 N 4 (Ni/Co-CN) material with the appearance of flower-like nanosheets was prepared by the hydrothermal method. A perfect composite structure can exert a synergistic effect between materials, thereby improving their overall electrochemical performance. • The Ni/Co-CN material was synthesized through a simple hydrothermal process for excellent performance supercapacitors. • The prepared hollow Co 2 NiO 4 cubes derived from ZIF-67 were successfully decorated with flower-like g-C 3 N 4 nanosheets. • The Ni/Co-5 %CN has a superior specific capacitance of 1701 F g −1 at 1 A g −1 and better cycle stability. • The asymmetric supercapacitor shows an high energy density of 51.38 Wh kg −1 at the power density of 729.9 W kg −1 .