Covalent Graphene-MOF Hybrids for High-Performance Asymmetric Supercapacitors.
basic_science · Level V
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- Record sourced from PubMed, PMID 33274794.
- Also identified by DOI 10.1002/adma.202004560 and PMC identifier 11468759.
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Abstract
In this work, the covalent attachment of an amine functionalized metal-organic framework (UiO-66-NH<sub>2</sub> = Zr<sub>6</sub> O<sub>4</sub> (OH)<sub>4</sub> (bdc-NH<sub>2</sub> )<sub>6</sub> ; bdc-NH<sub>2</sub> = 2-amino-1,4-benzenedicarboxylate) (UiO-Universitetet i Oslo) to the basal-plane of carboxylate functionalized graphene (graphene acid = GA) via amide bonds is reported. The resultant GA@UiO-66-NH<sub>2</sub> hybrid displayed a large specific surface area, hierarchical pores and an interconnected conductive network. The electrochemical characterizations demonstrated that the hybrid GA@UiO-66-NH<sub>2</sub> acts as an effective charge storing material with a capacitance of up to 651 F g<sup>-1</sup> , significantly higher than traditional graphene-based materials. The results suggest that the amide linkage plays a key role in the formation of a π-conjugated structure, which facilitates charge transfer and consequently offers good capacitance and cycling stability. Furthermore, to realize the practical feasibility, an asymmetric supercapacitor using a GA@UiO-66-NH<sub>2</sub> positive electrode with Ti<sub>3</sub> C<sub>2</sub> T<sub>X</sub> MXene as the opposing electrode has been constructed. The cell is able to deliver a power density of up to 16 kW kg<sup>-1</sup> and an energy density of up to 73 Wh kg<sup>-1</sup> , which are comparable to several commercial devices such as Pb-acid and Ni/MH batteries. Under an intermediate level of loading, the device retained 88% of its initial capacitance after 10 000 cycles.