Square-Facet Nanobar MOF-Derived Co₃O₄@Co/N-doped CNT Core–Shell-based Nanocomposites as Cathode Materials for High-Performance Supercapacitor Studies

Abstract

The binary as well as ternary nanocomposites of the square-facet nanobar Co-MOF-derived Co3O4@Co/N-CNTs (N-CNTs: nitrogen-doped carbon nanotubes) with Ag NPs and rGO have been synthesized via an easy wet chemical route, and their supercapacitor behavior was then studied. At a controlled pH of the precursor solution, square-facet nanobars of Co-MOF were first synthesized by the solvothermal method and then pyrolyzed under a controlled nitrogen atmosphere to get a core–shell system of Co3O4@Co/N-CNTs. In the second step, different compositions of Co3O4@Co/N-CNT core–shell structures were formed by an ex-situ method with Ag NPs and rGO moieties. Among several bare, binary, and ternary compositions tested in 6 M aqueous KOH electrolyte, a ternary nanocomposite having a 7.0:1.5:1.5 stoichiometric ratio of Co3O4@Co/N-CNT, Ag NPs, and rGO, respectively, reported the highest specific capacitance (3393.8 F g–1 at 5 mV s–1). The optimized nanocomposite showed the energy density, power density, and Coulombic efficiency of 74.1 W h.kg–1, 443.7 W.kg–1, and 101.3%, respectively, with excellent electrochemical stability. After testing an asymmetrical supercapacitor with a Co3O4@Co/N-CNT/Ag NPs/rGO/nickel foam cathode and an activated carbon/nickel foam anode, it showed 4.9 W h.kg–1 of energy density and 5000.0 W.kg–1 of power density.

ZnO Nanorod/Multiwalled Carbon Nanotube Composites Sensitized with Cu-Based Metal–Organic Frameworks as Photoanodes for Solar-Driven Water Splitting

“…Such a higher surface area reveals the high anchoring of ZnO with MWCNTs, which provides improved activity of ZC-0.1 compared to bare ZnO NRs. The higher surface area of ZC-0.1 NCs permits the competent anchoring of Cu-BTC MOFs on the NC surface along with a proper interface with high contact between the photoanode and electrolyte …”

Design and photovoltaic studies of W@TiO2/rGO nanocomposites with polymer gel electrolyte

“…50 In addition, the pore size of all samples is in the range of 1.8 to 3.0 nm, which confirms the mesoporous nature of the samples, and such mesoporous samples can be effectively utilized for the said study. 51 A high surface area with a porous surface can lead to enhanced surface roughness, which can be associated with boosted photoelectrochemical performance due to more active sites. So, these can provide more access to the dye for sensitization over the surface, and this can be effective for the photoactive nature of the samples.…”

Cobalt/Nitrogen Co‐Doped Carbon Materials Enhance the Reaction Rate of Sodium–Potassium Alloy Electrodes

“…For the C 1s spectra, four bonds would be classified as C═O (286.9 eV), C─N and C─O (285.4 eV), C─C and C═C (284.8 eV), and O─C─O (289.5 eV) in the Co/N@CNT material, which is similar to N@CNT. [29,30] In contrast, after the reaction, "graphitic" nitrogen and NaK alloys are prone to dissociate and form C─K bonds by reaction with NaK alloy clusters, while the enhancement of O─C─O, C═O, and C─O is due to the presence of large amounts of diethyl carbonate (DEC) and ethyl carbonate (EC) residing in the electrolyte. [31,32] In addition, the K─O 2p 1/2 and K─O 2p 3/2 bonds that appeared after the reaction were attributed to the formation of SEI films at the electrode interface and the reaction of potassium with traces of air in the glove box during the reaction (Figure S6c, Supporting Information).…”