An asymmetric supercapacitor fabricated with CoAl-layered double hydroxide/graphene foam (LDH/GF) composite as the positive electrode and activated carbon derived from expanded graphite (AEG) as negative electrode in aqueous 6 M KOH electrolyte is reported. This CoAl-LDH/GF//AEG cell achieved a specific capacitance of 101.4 F g -1 at a current density of 0.5 A g -1 with a maximum energy density as high as 28 Wh kg -1 and a power density of 1420 W kg -1 . Furthermore, the supercapacitor also exhibited an excellent cycling stability with ∼ 100% capacitance retention after 5000 charging-discharging cycles at a current density of 2 Ag -1 . The results obtained show the potential use of the CoAl-LDH/GF//AEG material as suitable electrode for enhanced energy storage as supercapacitor.

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In this work, a series of nitrogen-doped multi-walled carbon nanotubes (N-MWCNTs) with several weight percentages (0.1, 0.4, 0.8, and 1.0 wt.%) were synthesized by catalytic chemical vapor deposition (CCVD) technique. The N-MWCNTs were first characterized and then dispersed in high-density polyethylene (HDPE) polymer matrix to form a nanocomposite. The HDPE/N-MWCNT nanocomposite films were prepared by melt mixing and hot pressing; a good dispersion in the matrix and a good N-MWCNT-polymer interfacial adhesion have been verified by scanning electron microscopy (SEM). Raman spectroscopy measurements have been performed on prepared samples to confirm the presence and nature of N-MWNTs in HDPE matrix. The X-ray diffraction (XRD) analysis demonstrated that the crystalline structure of HDPE matrix was not affected by the incorporation of the N-MWNTs.

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A membranous shaped Ni/Zn layered double hydroxide based nanohybrid was obtained using a low-cost template-free hydrothermal process at optimized growth conditions of 180 °C for 6 h. The synthesized nanohybrid was structurally, texturally and morphologically characterized using different techniques such as X-ray diffraction, FTIR, XPS spectroscopy, BET analysis and FESEM microscopy. The adsorption performance of our product was estimated through the Azorubine dye removal from synthetic wastewater. We therefore studied the synergic effects of Ni/Zn adsorbent dosage, contact time, pH, adsorbate concentration, stirring speed and temperature on the Azorubine adsorption efficiency. In this investigation, we obtained bi-structure based nanoadsorbent with 54% crystallinity order composed of nickel hydrate and zinc carbonate hydroxides in irregular nanoflake-like mesoporous nanohybrid morphology. Interestingly, it was also revealed to have high specific surface area (SSA) of around 110 m2 g−1 with important textural properties of 18 nm and 0.68 cm3 g−1 average pore size and volume, respectively. Moreover, the adsorption results revealed that this novel Ni/Zn layered double hydroxide (Ni/Zn LDH) was an efficient adsorbent for Az molecule and possesses an adsorptive ability exhibiting a short equilibrium time (60 min) and a high Az adsorption capability (223 mg g−1). This fast removal efficiency was attributed to high contact surface area via mesoporous active sites accompanied with the presence of functional groups (OH− and CO32−). In addition, the Langmuir and Freundlich isotherms were studied, and the results fitted better to the Langmuir isotherm.

In this investigation, nickel hydroxide Ni(OH) 2 based nanostructured materials were synthesized by simple and low cost free template hydrothermal method at two different growth temperatures with and without SDS surfactant. The X-ray diffraction, Raman spectroscopy and field emission scanning electron microscopy analysis confirmed the formation of β-Ni(OH) 2 pure brucite crystalline phase in spherical nanoparticle morphology with an average diameter ranging from 8 to 27 nm. In the second step, these nanospherical agglomerated hydroxide particles with activated carbon addition were performed as electroactive materials deposited on nickel foam current collector as working electrodes. The electrochemical tests in a three-electrode configuration using 6 MKOH electrolyte show that the best electroactive NPs (β bc-Ni(OH) 2 and β-Ni(OH) 2 obtained at optimized conditions, have a maximum specific capacitance (C s) of 4697 F g −1 and 3431 F g −1 at 5 mV s −1 scan rate with a specific capacity (Q s) of 744 mAh g −1 and 618 mAh g −1 at 1 A g −1 current density with an R s of about 0.24 and 0.28 Ω, respectively. At 30 A g −1 after 1700 cycles, the coulombic retention is around 99.06% (or capacity retention 109 mAh g −1), demonstrating remarkable cycling stability for Ni based hydroxide.

In this investigation, we report the synthesis of novel homogeneous micro-mesoporous bi-phase nanohybrids based on Ni/Zn hydroxides using a simple and low-cost free-template urea-based hydrothermal process at two different growth temperatures (120 and 180 °C) for 6 h in two cases of precursor ratios (Ni:Zn = 1:1 and Ni:Zn = 1:2). The synthesized products have been characterized with different techniques such as XRD, FT-IR, FESEM, Raman, BET and XPS analysis to identify quantitatively and qualitatively their original physico-chemical properties. The obtained structural results show the formation of bi-hydroxide-based products: α * -Ni(OH) 2 •0.75 H 2 O with Zn 5 (CO 3 ) 2 (OH) 6 (case Ni:Zn = 1:1) or with Zn 4 (CO 3 )(OH) 6 •H 2 O (Ni:Zn = 1:2) which are also proven by FTIR and Raman analyses. However, the obtained 3D micro-meso-nanohybrids with different pore morphology have been demonstrated through the FESEM micrographs depending on the synthesis conditions. Moreover, these porous products have been subjected to textural studies with the BET results showcasing a porous morphology with a reasonable specific surface area (SSA) and pore volume in the range (70-150 m 2 /g) and (0.19-0.85 cm 3 /g), respectively. Also, a clear improvement in the BET SSA (two times the initial value) was obtained with increasing the growth temperature in the two cases (1:1 and 1:2). Consequently, we have successfully synthesized active mesoporous materials with interesting specific surface area and porosity (pore volume and size) which make them attractive materials for electrode applications especially in energy storage and biosensing.