No abstract

3-D ZnFe2O4/FSSM-300 nano-flakes on flexible stainless steel mesh as anode and Ni(OH)2/FSSM-300 as cathode was used to fabricate an asymmetric supercapacitor.

Heterostructure-based metal oxide thin films are recognized as the leading material for new generation, high-performance, stable, and flexible supercapacitors. However, morphologies, like nanoflakes, nanotubes, nanorods, and so forth, have been found to suffer from issues related to poor cycle stability and energy density. Thus, to circumvent these problems, herein, we have developed a low-cost, high surface area, and environmentally benign self-assembled ZnFeO nanoflake@ZnFeO/C nanoparticle heterostructure electrode via anchoring ZnFeO and carbon nanoparticles using an in situ biomediated green rotational chemical bath deposition approach for the first time. The synthesized ZnFeO nanoflake@ZnFeO/C nanoparticle heterostructure thin films demonstrate an excellent specific capacitance of 1884 F g at a current density of 5 mA cm. Additionally, all solid-state flexible asymmetric supercapacitor devices were designed on the basis of ZnFeO nanoflake@ZnFeO/C nanoparticle heterostructures as the negative electrode and reduced graphene oxide and energy density of 81 Wh kg at a power density of 3.9 kW kg. Similarly, the asymmetric device exhibits ultralong cycle stability of 35 000 cycles by losing only 2% capacitance. The excellent performance of the device is attributed to the self-assembled organization of the heterostructures. Moreover, the in situ biomediated green strategy is also applicable for the synthesis of other metal oxide and carbon-based heterostructure electrodes.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used for an in situ thermal decomposition study of Zn(CH 3 COO) 2 ·2H 2 O forming ZnO nanoparticles. TOF-SIMS spectra were recorded at regular temperature intervals of 25• C in positive and negative detection modes in a dynamic thermal process.Controlled heating (5 • C min −1 ) of Zn(CH 3 COO) 2 ·2H 2 O was also carried out using thermogravimetric analysis (TGA) in an oxygen atmosphere (20 ml min −1 ). Nearly spherical ZnO nanoparticles with no agglomeration and a narrow size distribution (diameter ∼50 nm) were observed, which were characterized using scanning electron microscopy, transmission electron microscopy and x-ray diffraction. In situ thermo-TOF-SIMS was used to monitor the 64 Zn + and 66 Zn + ion abundances as a function of temperature, which showed a similar profile to that observed for weight loss in TGA during decomposition. Based on the experimental results, a possible decomposition mechanism for the formation of ZnO is proposed.

Herein, we are reporting a simple, economic, easy to handle, scalable and reproducible mechanochemical i.e. rotational chemical bath deposition (R-CBD) approach for synthesis of well adhered nano-flakes ZnFe2O4 thin films (NFs-ZnFe2O4) with uniform morphology on stainless steel (SS) substrate, in comparison with nano-grain ZnFe2O4 thin films (NGs-ZnFe2O4) prepared using conventional CBD approach. The influence of rotation on the evolution of nano-flakes morphology in NFs-ZnFe2O4 is also investigated. The porous NFs-ZnFe2O4 thin films demonstrated excellent pseudocapacitor properties with higher specific capacitance 768 Fg -1 at high current density 5 mA cm -2 , stability upto 5000 cycles (88% retention), higher energy density (106 Wh kg -1 ) and power density (18 kW kg -1 ) compared to NGs-ZnFe2O4. The results were also found to be higher than those reported earlier for MFe2O4 based systems.

No abstract

No abstract

Silver nanoparticles were deposited on the surface of natural wool with the aid of powered ultrasound. The average particle size was 5-10 nm, but larger aggregates of 50-100 nm were also observed. The sonochemical irradiation of a slurry containing wool fibers, silver nitrate, and ammonia in an aqueous medium for 120 min under an argon atmosphere yielded a silver-wool nanocomposite. By varying the gas and reaction conditions, we could achieve control over the deposition of the metallic silver particles on the surface of the wool fibers. The resulting silver-deposited wool samples were characterized with X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, high-resolution scanning electron microscopy, electron-dispersive X-ray analysis, Brunauer, Emmett, and Teller physical adsorption method, X-ray photoelectron spectroscopy, and Raman and diffused reflection optical spectroscopy. The results showed that the strong adhesion of the silver to the wool was a result of the adsorption and interaction of silver with sulfur moieties related to the cysteine group.