[en] Highly ordered silver nanowire arrays were prepared using a new effective template method, in which silver ions and acetaldehyde were conversely transported into the nanochannels of porous anodic aluminum oxide (AAO) templates by diffusion or convection, and then reacted to form the one-dimension structure of silver by confining growth. Electron microscope images show that the silver nanowires are abundant, parallel and well-ordered in large-area. It is estimated that the diameter of the individual nanowire is about 60 nm and the length is more than 30 μm. The data of X-ray diffraction and selected area electron diffraction (SAED) patterns indicate that the silver nanowire is crystalline with face-centered-cubic structure

[en] Ordered CeO₂ nanowire arrays embedded in anodic alumina membranes (AAM) were fabricated by a novel technique, in which anions and cations conversely migrated into the hexagonally ordered nanochannels of the AAM and reacted inside the channels to form one-dimensional nanostructures. The transmission electron microscopy (TEM) images show that CeO₂ nanowires are about 60 nm in diameter, which correspond to the pore sizes of the membranes used. The selected-area electron diffraction (SAED) pattern indicates that the nanowires selected are single crystals. The scanning electron microscopy (SEM) images show that the resultant nanowires are abundant and uniform. The X-ray diffraction (XRD) spectra indicate that the CeO₂ nanowires are cubic crystalline structure. The X-ray photoelectron spectroscopy (XPS) spectra data demonstrate that stoichiometric CeO₂ is formed

[en] Chemical effects in different aqueous solutions induced by plasma with glow discharge electrolysis (GDE) and contact glow discharge electrolysis (CGDE) are described. The experimental and discharge characteristics are also reviewed. These are followed by a discussion of their mechanisms of both anodic and cathodic CGDE

[en] We report a one-step fabrication of α-iron oxyhydroxide/reduced graphene oxide (α-FeOOH/rGO) composites, in which the ferrous sulfate (FeSO₄·7H₂O) are used as the iron raw and reducing agent to grow goethite (α-FeOOH) and reduce graphite oxide (GO) to rGO in the same time. The morphology, composition and microstructure of the as-obtained samples are systematically characterized by thermogravimetric (TG) analysis, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and FT-IR. Moreover, their electrochemical properties are investigated using cyclic voltammetry and galvanostatic charge/discharge techniques. The specific capacitance of 452 F g⁻¹ is obtained at a specific current of 1 A g⁻¹ when the mass ratio of α-FeOOH to rGO is up to 80.3:19.7. In addition, the α-FeOOH/rGO composite electrodes exhibit the excellent rate capability (more than 79% retention at 10 A g⁻¹ relative to 1 A g⁻¹) and well cycling stability (13% capacitance decay after 1000 cycles). These results suggest the importance and great potential of α-FeOOH/rGO composites in the applications of high-performance energy-storage. - Graphical abstract: α-FeOOH loaded on rGO sheets reveals excellent super-capacitive performance. Display Omitted - Highlights: • A one-step synthesis of the environmentally friendly electrode material is designed. • Ferrous sulfate is used as both iron raw source of goethite and reductant of GO. • α-FeOOH nanorods loaded on rGO sheets arrange into a raft-like array. • The resultant composite exhibits high specific capacitance and long cycling stability

[en] Graphical abstract: Electroactive methyl green (MG) is selected to functionalize reduced graphene oxide (RGO) through non-covalent modification and the composite achieves high specific capacitance, good rate capability and excellent long life cycle. - Highlights: • MG–RGO composites were firstly prepared through non-covalent modification. • The mass ratio in composites is a key for achieving high specific capacitance. • MG–RGO 5:4 exhibits the highest specific capacitance of 341 F g"−"1. • MG–RGO 5:4 shows excellent rate capability and long life cycle. - Abstract: In the present work, water-soluble electroactive methyl green (MG) has been used to non-covalently functionalize reduced graphene oxide (RGO) for enhancing supercapacitive performance. The microstructure, composition and morphology of MG–RGO composites are systematically characterized by UV–vis absorption, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrochemical performances are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS). The fast redox reactions from MG could generate additional pseudocapacitance, which endows RGO higher capacitances. As a result, the MG–RGO composite (with the 5:4 mass ratio of MG:RGO) achieve a maximum value of 341 F g"−"1 at 1 A g"−"1 within the potential range from −0.25 to 0.75 V and provide a 180% enhancement in specific capacitance in comparison with pure RGO. Furthermore, excellent rate capability (72% capacitance retention from 1 A g"−"1 to 20 A g"−"1) and long life cycle (12% capacitance decay after 5000 cycles) are achieved for the MG–RGO composite electrode

[en] Research highlights: → We first synthesized α-Ni(OH)₂ nanowires without substitution. → Adopted the conversely migrate technique. → Ni(OH)₂ nanowires exhibited an excellent electrochemical capacitive behavior. → α-Ni(OH)₂ nanowire is promising for electrochemical capacitor applications. - Abstract: Alpha-nickel hydroxide nanowire with diameter of 60 nm was successfully synthesized by conversely migrates technique. Structural and morphological characterizations were performed using power X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The capacitive properties were evaluated by cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy technique in 6 M KOH aqueous electrolyte. A maximum specific capacitance of 833 F g^-1 was obtained at constant current of 5 mA, indicating that the α-nickel hydroxide nanowire is a promising electrode material for electrochemical capacitors.

[en] 5, 7, 12, 14-pentacenetetrone (PT), polycyclic quinone derivatives, are rich in carbonyl, which were investigated as a novel organic electrode material for supercapacitors. PT with a π conjugated system, is a flat molecule, generating strong π–π interactions between molecules. PT molecules were uniformly fixed on conductive reduced graphene oxide (rGO) through π–π interaction by one-step solvothermal method, forming a three-dimensional cross-linked PT@rGO hydrogel. This composite structure was conducive to reducing the charge transfer resistance and promoting the Faraday reaction of electrode, which achieved the superposition of electric double-layer capacitance and pseudocapacitance. Appropriate organic molecular loading can effectively improve electrochemical performance. The optimal PT@rGO electrode material displayed the specific capacitance of 433.2 F g⁻¹ at 5 mV s⁻¹ with an excellent rate capability in 1 mol l⁻¹ H₂SO₄ electrolyte. Finally, the fully pseudocapacitive asymmetric supercapacitor has been assembled by using PT@rGO as positive electrode and benz[a]anthracene-7,12-quinone (BAQ) modified rGO(BAQ/rGO)as negative electrode, which exhibited the good energy storage performance in a cell voltage of 1.8 V. (paper)

[en] A flexible self-supporting and binder-free supercapacitor electrode is fabricated by embedding a polypyrrole (PPy) nanostructured network into only one side of a graphene thin film via a spin coating method and a subsequent hydrothermal process. Based on the amphiphilic nature of the graphene oxide (GO) thin film, the well-defined PPy nanoparticles are well dispersed and form a reticular structure on the thin film surface. After reduction treatment at a temperature of 180 degrees C, the reduced graphene oxide (rGO) thin film not only provides a large accessible surface area for the dispersion of PPy nanoparticles but also acts as a binder-free conductive current collector. The polypyrrole/graphene film (PGF) electrode material exhibits an excellent electrochemical performance in the three-electrode configuration, including a high specific capacitance of up to 455 F g^-1 at 1 A g^-1 and outstanding cycling stability (97% capacitance retention after 1000 cycles). In addition, the symmetric PGF supercapacitor shows a specific capacitance of up to 49.3 F g^-1 at a cell voltage of 1.4 V and exhibits a maximum energy density of 13.4 W h kg^-1 at a power density of 700 W kg^-1, with 96% capacitance retention after 1000 cycles. This work shows impressive potential in fabricating high-performance flexible electrodes for supercapacitors. (authors)

[en] Highlights: ► We prepared a composite film which has bi-layers with asymmetric microstructure and relatively rich porosity which provides larger surface area for electrochemical reaction. ► The outer polysulfone layer is propitious for the organic molecules to enrich on the composite film, which brings great enhancement in electron transfer kinetics. ► The composite film electrode can be used to detect qualitatively or quantitatively hydroquinone and catechol in the single solute or mixed systems. - Abstract: Polyaniline (PAN)/polysulfone (PSF) composite film electrodes were successfully prepared by electropolymerization using cyclic votammetry technique. The composite film electrodes show a great enhancement in electron transfer kinetics, and the separation between oxidation and reduction peaks (ΔE_p) decreases from 200 to 35 mV for hydroquinone (H₂Q) and from 275 to 42 mV for catechol (CC) at bare Pt and composite film electrodes respectively. In their mixed systems, the redox peak of H₂Q and two pairs of redox peaks of CC on this composite film electrode could be obviously distinguished which indicates the composite film electrodes have excellent electrocatalytic activity and reversibility towards the oxidation of two diphenols (hydroquinone and catechol). The linear relationships between the peak current and concentration are observed for single solute and mixed systems within the certain concentration range, implying that the composite film electrodes have potential application in the qualitative or quantitative analysis of diphenol.

[en] A novel nanostructured mesoporous Co_xNi_1-x layered double hydroxides (Co_xNi_1-x LDHs), which both Co(OH)₂ and Ni(OH)₂ exhibit, has been successfully synthesized by a chemical co-precipitation route using polyethylene glycol as the structure-directing reagent. Structural and morphological characterizations were performed using powder X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The component and thermal stability of the sample were measured by energy dispersed X-ray spectrometry (EDS), FT-IR and thermal analyses, including thermogravimetry (TG) and differential thermal analysis (DTA). Cyclic voltammogram and galvanostatic charge-discharge testified that the Co_xNi_1-x LDH has a specific capacitance of 1809 F g^-1 at a current density of 1 A g^-1 and remains at about 90.2% of the initial value after 1000 cycles at a current density of 10 A g^-1. The relationship between the chemical composition and the capacitance is discussed