Significantly enhanced electrochemical performance of 2D Ni-MOF by carbon quantum dot for high-performance supercapacitors

Abstract

Rational design of metal-organic framework (MOF) materials with rich active sites and high conductivity is very important for their applications in the energy storage devices, but it is still a great challenge. Herein, carbon quantum dot (CQD)/NiMOF composites are synthesized via a one-pot hydrothermal method. The experimental results show that CQDs can effectively enhance the electrical conductivity of NiMOF and regulate its morphology to expose abundant active sites, which are beneficial for electrochemical performance. The as-prepared CQD@MOF composite delivers a specific capacitance of 2457.9 F g−1 at 1 A g−1, and the outstanding cycling stability with the capacitance retention of 84.5% after 5000 charge/discharge cycles. Moreover, the hybrid supercapacitors with activated carbon (AC) as the negative electrode and CQD@MOF as the positive electrode exhibits a wide voltage window of 1.7 V and a high energy density of 67.1 Wh kg−1 at a power density of 5.1 kW kg−1. The results can effectively boost the electrochemical performance of MOF and promote its application in supercapacitor electrode materials.