NiWO4/Ni/Carbon Composite Fibres for Supercapacitors with Excellent Cycling Performance

Pyrazinamide photodegradation on NiWO4-palygorskite nanocomposites under polychromatic irradiation

In this work, antibiotic pyrazinamide (PZA) photodegradation on palygorskite (Pal), NiWO₄ crystals, and NiWO₄-Pal (2, 6, and 10%) nanocomposites was evaluated under polychromatic irradiation. In the characterization of the samples, XRD patterns displayed good crystallinity for NiWO₄ crystals and nanocomposites. In addition, the diffractograms were used in the Rietveld refinement for phase indexing, revealing a wolframite-type monoclinic structure with the space group P2/c. The active vibrational modes related to the characteristic groups of the samples were identified using Raman and FTIR spectroscopy. Photoluminescence (PL) spectra revealed that NiWO₄ and NiWO₄-Pal (2%) nanocomposite have the highest electron-hole pair recombination rate, and the contribution of the green component in the NiWO₄-Pal (2%) nanocomposite indicates a greater contribution of deep energy levels to the PL profile. DRS in the UV-visible region indicated that NiWO₄ crystals have indirect band-gap energy (E_gap) 2.64 eV; NiWO₄-Pal (2, 6, and 10%) nanocomposites have 2.62, 2.58, and 2.59 eV, respectively; and Pal has 2.83 eV. The catalytic tests showed that the NiWO₄-Pal (2%) nanocomposite samples, under polychromatic radiation, exhibit greater efficiency in photodegradation at 110 min, with yield of 98.5%. The ROS tests indicated that the studied reactive species play a similar role in PZA photodegradation.

Investigation on NiWO4/PANI composite as an electrode material for energy storage devices

NiWO4/PANI was synthesized by an in situ chemical oxidative polymerization route. Incorporation of NiWO4 in a PANI matrix rendered high specific capacitance and salient morphological features.

Agar Hydrogel Template Synthesis of Mn₃O₄ Nanoparticles through an Ion Diffusion Method Controlled by Ion Exchange Membrane and Electrochemical Performance

A novel strategy, ion diffusion method controlled by ion exchange membrane combining with agar hydrogel template, was reported for the synthesis of Mn₃O₄ nanoparticles without any oxidizing agents. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Brunauere-Emmette-Teller (BET) isotherm were carried out to characterize the structure, morphology, pore size and distribution and specific surface area of the as-prepared nanomaterials. It is shown that the morphology and size of Mn₃O₄ nanoparticles can be controlled by the concentration of agar hydrogel. All the specific capacitances of the Mn₃O₄ samples prepared with agar hydrogel template are much higher than that of Mn₃O₄ prepared without any template agent. The Mn₃O₄ sample prepared at 1.5 g L-1 of agar hydrogel solution exhibits a highest specific capacitance of 183.0 F g-1 at the current density of 0.5 A g-1, which is increased by 293% compared with that of Mn₃O₄ synthesized without any template agent. The results indicate that the ion diffusion method controlled by ion exchange membrane combining with agar hydrogel template is a convenient and effective approach for preparing inorganic nanomaterials.

Solvothermal synthesis of NiWO4 nanostructure and its application as a cathode material for asymmetric supercapacitors

This study proposes a facile solvothermal synthesis of nickel tungstate (NiWO4) nanowires for application as a novel cathode material for supercapacitors. The structure, morphology, surface area and pore distribution were characterized and their capacitive performances were investigated. The results showed that the NiWO4 nanowires synthesized in ethylene glycol solvent could offer a high specific capacitance of 1190 F g-1 at a current density of 0.5 A g-1 and a capacitance retaining ratio of 61.5% within 0.5-10 A g-1. When used as a cathodic electrode of an asymmetric supercapacitor (ASC), the NiWO4 nanowire based device can be cycled reversibly in a high-voltage region of 0-1.7 V with a high specific capacitance of 160 F g-1 at 0.5 A g-1, which therefore contributed to an energy density of 64.2 W h kg-1 at a power density of 425 W kg-1. Moreover, 92.8% of its initial specific capacitance can be maintained after 5000 consecutive cycles (5 A g-1). These excellent capacitive properties make NiWO4 a credible electrode material for high-performance supercapacitors.

Fabrication of graphene/copper–nickel foam composite for high performance supercapacitors

An rGO/PDA/CNF composite electrode is fabricated by an immersing and annealing process and exhibits superior electrochemical performance.

Synthesis, characterization, and enhanced photocatalytic properties of NiWO4 nanobricks

NiWO₄ nanobricks were used as photocatalysts in the degradation of organic pollutants in neutral and basic media.