Polyoxometalate-Incorporated Metallacalixarene@Graphene Composite Electrodes for High-Performance Supercapacitors

Abstract

Composites of polyoxometalate (POM)/metallacalixarene/graphene-based electrode materials not only integrate the superiority of the individual components perfectly but also ameliorate the demerits to some extent, providing a promising route to approach high-performance supercapacitors. Herein, first, we report the preparations, structures, and electrochemical performance of two fascinating POM-incorporated metallacalixarene compounds [Ag5(C2H2N3)6]­[H5 ⊂ SiMo12O40] (1) and [Ag5(C2H2N3)6]­[H5 ⊂ SiW12O40] (2); (C2H2N3 = 1H-1,2,4-triazole). Single-crystal X-ray diffraction analyses illustrated that both 1 and 2 possess intriguing POM-sandwiched metallacalix[6]­arene frameworks. Nevertheless, our investigations, including the electrochemical cyclic voltammetry, galvanostatic charge–discharge tests, and electrochemical impedance spectroscopy, reveal that the oxidation ability of the Keggin ions is a primary effect in electrochemical performance of these POM-incorporated metallacalixarene compounds. Namely, the electrodes containing Mo as metal atoms in the Keggin POM shows much higher capacitance than the corresponding W-containing ones. Moreover, compound 1@graphene oxide (GO) composite electrodes are fabricated and systematically explored for their supercapacitor performance. Thanks to the synergetic effects of GO and POM-incorporated metallacalixarenes, the compound 1@15%GO-based electrode exhibits the highest specific capacitance of up to 230.2 F g–1 (current density equal to 0.5 A g–1), which is superior to majority of the reported POM-based electrode materials.

Redox Tuning in Crystalline and Electronic Structure of Bimetal–Organic Frameworks Derived Cobalt/Nickel Boride/Sulfide for Boosted Faradaic Capacitance

“…[38,39] The electrochemically active surface area (ECSA) of Co-Ni MOF and its derivatives are also evaluated through the CV measurements at the potential window (0-0.1 V versus Hg/HgO) ( Figure S10, Supporting Information). [8,9,19] The specific electrical double layer capacitance (C dl ) of Co-Ni MOF, Co-Ni-B, Co-Ni-B-S, Co-Ni-S, and Co-Ni-S-B is 110.66, 45.8, 145.4, 48, and 2.5 F g −1 , respectively. It can be concluded that the ECSA of Co-Ni-B-S is much larger than that of the initial Co-Ni MOF electrode, suggesting their enhanced electrochemical performance in aqueous electrolyte, and authorizing the superiority of this structure.…”

“…Extensive energy demands by portable electronics and electric vehicles have indorsed the rapid development of highly efficient energy storage technologies for human society . Electrochemical capacitors (ECs) have received significant attention as a strong candidate in virtue of high power density, fast charging rate, and long‐term cyclability . Since the performance metrics and energy storage mechanism of ECs depend on the electrode materials, extensive investigations have been performed to optimize the structure and electronic valence of inorganic materials to improve the energy density …”

“…The Co‐Ni‐B‐S presents the highest capacitance with two pairs of redox peaks at the scan rate of 20 mV s −1 , whereas only one pair for the other materials (Co‐Ni MOF, Co‐Ni‐B, Co‐Ni‐S, and Co‐Ni‐S‐B) is resulted from the Co/Ni multivalences and amorphous structure after the redox treatment . The electrochemically active surface area (ECSA) of Co‐Ni MOF and its derivatives are also evaluated through the CV measurements at the potential window (0–0.1 V versus Hg/HgO) (Figure S10, Supporting Information) . The specific electrical double layer capacitance ( C dl ) of Co‐Ni MOF, Co‐Ni‐B, Co‐Ni‐B‐S, Co‐Ni‐S, and Co‐Ni‐S‐B is 110.66, 45.8, 145.4, 48, and 2.5 F g −1 , respectively.…”

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Electrochemical capacitors (ECs) have received significant attention as a strong candidate in virtue of high power density, fast charging rate, and long-term cyclability. [2,[5][6][7][8][9] Since the performance metrics and energy storage mechanism of ECs depend on the electrode materials, extensive investigations have been performed to optimize the structure and electronic valence of inorganic materials to improve the energy density. [10] Recently, metal-organic frameworks (MOFs), which are self-assembled by metal ions (or metal clusters) with organic ligands in high crystallinity and longrange order, are considered as emerging porous materials for electrochemical energy storage applications.

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Multi‐Interface‐Modulated CoS2@MoS2 Nanoarrays Derived by Predesigned Germanomolybdate Polymer Showing Ultrahighly Electrocatalytic Activity for Hydrogen Evolution Reaction in Wide pH Range

“…In the {Co 2 L 3 •6H 2 O} + , two Co 2+ metals, three L − molecules and six water molecules (Figure 1, (Figure 1, middle). [54][55][56][57] Moreover, the {Co 2 L 3 •6H 2 O} + clusters and adjacent GeMo 12 polyanions are integrated together through massive hydrogen bond interactions ( Figure S3, Supporting Information) to fabricate a 3D supermolecular structure ( Figure 1).…”