Charge regulation for advanced electrode combining ZrNi-UiO-66 and carbon quantum dots towards high specific capacitance

Introducing advanced conductive nanoparticles to combine with metal-organic frameworks (MOFs) as electrode is emergingly regarded as a practical and efficient approach to improve the capacitive performance of supercapacitors. Herein, a new MOF (ZrNi-UiO-66, Nickel-zirconium 1,4-dicarboxybenzene) is designed to combine with carbon quantum dots (CQDs) to form a composite electrode with high specific capacitance, in which the charge regulation is performed to facilitate the electronic conduction and transfer. Such constructed electrode delivers an enhanced electronic conductivity and an improved specific capacitance of 2468.75 F g −1 @ 1 A g −1 , which is four times of the contrast sample. Meanwhile, the assembled hybrid supercapacitor exhibits an increased energy density and power density, as well as a sustainable stability after 10,000 cycles with a retention rate of 91.6 %. Basing on the study of advanced characterizations and density functional theory (DFT) simulation, the mechanism of significantly improved specific capacitance can be elaborated as the promote electronic conduction caused from narrowed band gap from 3.9 eV or 0.41 eV–0.23 eV, and the increased charge accumulation at the Ni sites in designed MOFs. This work provides new insights for the design and construction of potential energy storage materials based on MOFs and/or advanced carbon-based materials.