Oxygen vacancy-rich doped CDs@graphite felt-600 heterostructures for high-performance supercapacitor electrodes

Carbon dots (CDs) have attracted much attention owing to their distinctive 0D chemical structure, ultra-small size, and intrinsic surface/edge defects, and have been widely used in many kinds of research fields. In this work, a facile method to synthesize an oxygen vacancy-rich doped CDs@graphite felt-600 heterostructure with outstanding electrochemical properties is presented. The electron spin resonance (ESR) provides clear evidence for the existence of abundant oxygen vacancies in the CDs@graphite felt-600 heterostructure. The as-synthesized CDs@graphite felt-600 shows superior areal specific capacitance (5.99 F cm-2), due to abundant oxygen vacancies and extensive surface/edge defects in the heterostructure. In addition, a home-made coin cell supercapacitor (SC) with CDs@graphite felt-600 as the electrode delivers a large areal energy density of 20.7 μW h cm-2 at a power density of 150.0 μW cm-2. To determine the charge storage mechanism at the interface of CDs@graphite felt-600, the binding energies between the CDs and graphite felt are calculated by density functional theory (DFT).