Ferrocene functionalized multi-walled carbon nanotubes as supercapacitor electrodes

Modified multi-walled carbon nanotubes (MWCNTs) functionalized by a redox-active ferrocene (Fc-MWCNTs) were successfully synthesized to enhance the electrochemical performance of MWCNTs for supercapacitor application. The ferrocene moieties were attached to the surface of MWCNTs via a thiourea linker with anions-interacting capability. The Fc-MWCNTs were characterized using XPS, FTIR, SEM, TGA, DTG, and XRF methods. The electrochemical performance details were investigated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The Fc-MWCNTs electrode showed excellent capacity retention (90.8% over 5000 cycles) and a specific capacitance of 50 F g−1 at 0.25 A g−1 that is several times higher as compared to the pristine MWCNTs. The fabricated Fc-MWCNTs is proposed to be a suitable and promising candidate for energy storage material. de

Taguchi L25 (54) approach for methylene blue removal by polyethylene terephthalate nanofiber‐multi‐walled carbon nanotube composite

A membrane composed of polyethylene terephthalate nanofiber and multi‐walled carbon nanotubes (PET NF‐MWCNTs) composite is used to adsorb methylene blue (MB) dye from an aqueous solution. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ ray diffraction techniques are employed to study the surface properties of the adsorbent. Several parameters affecting dye adsorption (pH, MB dye initial concentration, PET NF‐MWCNTs dose, and contact time) are optimized for optimal removal efficiency (R, %) by using the Taguchi L25 (54) Orthogonal Array approach. According to the ANOVA results, pH has the highest contributing percentage at 71.01%, suggesting it has the most significant impact on removal efficiency. The adsorbent dose is the second most affected (12.08%), followed by the MB dye initial concentration of 5.91%, and the least affected is the contact time (1.81%). In addition, experimental findings confirm that the Langmuir isotherm is well‐fitted, suggesting a monolayer capping of MB dye on the PET‐NF‐MWCNT surface with a maximum adsorption capacity of 7.047 mg g−1. Also, the kinetic results are well‐suited to the pseudo‐second‐order model. There is a good agreement between the calculated (qe) and experimental values for the pseudo‐second‐order kinetic model

Solvothermal Synthesis of Reduced Graphene Oxide as Electrode Material for Supercapacitor Application

This work manifests the synthesis of reduced graphene oxide nanosheets through in situ solvothermal reduction of graphene oxide. The as-synthesized reduced graphene oxide nanosheets are utilized as a supercapacitor electrode. A series of structural and morphological investigations evince that graphene oxide can be successfully reduced through solvothermal strategy in absolute ethanol as solvent. Fourier transform infrared spectroscopy results showed that reduced graphene oxide displayed very low-intensity bands related to oxygenated functional groups, implying a high reduction degree. Besides that, it shows good electrochemical characteristics such as high specific capacitance of 183 F g-1 is obtained in 5 M KOH at 0.25 A g-1 and low internal and charges transfer resistances which are 430 and 64 mΩ, respectively. The findings confirm that graphene oxide can be reduced through solvothermal reduction strategy. Further, the as-prepared reduced graphene oxide nanosheets is a good candidate for supercapacitors application

W18O49 nanowires-graphene nanocomposite for asymmetric supercapacitors employing AlCl3 aqueous electrolyte

W18O49 nanowires (NWs)-reduced graphene oxide (rGO) nanocomposite is examined as a new active material for supercapacitors electrode, which reveals its high specific capacitance and excellent rate performance in AlCl3 aqueous electrolyte. Electrochemical studies show that the presence of rGO enhances Al3+ ions diffusion in the nanocomposite, thus provides more ions for intercalation pseudocapacitance. The fabrication of asymmetric supercapacitor W18O49 NWs-rGO//rGO demonstrates high specific capacitance of 365.5 F g−1 at 1 A g−1 and excellent cycling stability with 96.7% capacitance retention at 12,000 cycles. Interestingly, it delivers high energy density of 28.5 Wh kg−1 and power density of 751 W kg−1, which is the highest energy density value for all reported W18O49-based supercapacitor device. The work explores W18O49 NWs-rGO nanocomposite as a new electrode material for supercapacitors application with superior electrochemical performance, which may open up a new direction for high-performance energy storage in Al3+ electrolyte

One-step electrochemical synthesis of MoS2/graphene composite for supercapacitor application

In this study, an MoS2/graphene composite is fabricated from bulk MoS2 and graphite rod via a facile electrochemical exfoliation method. The as-prepared samples are characterized by X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy techniques to confirm the formation of the MoS2/graphene composite. The electrochemical behavior of the MoS2/graphene composite is evaluated through cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. It exhibits high specific capacitance of 227 F g−1 as compared with the exfoliated graphene (85 F g−1) and exfoliated MoS2 (70 F g−1) at a current density of 0.1 A g−1. This can be attributed to the synergistic effect between graphene and MoS2. Moreover, it displays high electrochemical stability and low electrical resistance