The development of new rechargeable battery systems could fuel various energy applications, from personal electronics to grid storage. Rechargeable aluminium-based batteries offer the possibilities of low cost and low flammability, together with three-electron-redox properties leading to high capacity. However, research efforts over the past 30 years have encountered numerous problems, such as cathode material disintegration, low cell discharge voltage (about 0.55 volts; ref. 5), capacitive behaviour without discharge voltage plateaus (1.1-0.2 volts or 1.8-0.8 volts) and insufficient cycle life (less than 100 cycles) with rapid capacity decay (by 26-85 per cent over 100 cycles). Here we present a rechargeable aluminium battery with high-rate capability that uses an aluminium metal anode and a three-dimensional graphitic-foam cathode. The battery operates through the electrochemical deposition and dissolution of aluminium at the anode, and intercalation/de-intercalation of chloroaluminate anions in the graphite, using a non-flammable ionic liquid electrolyte. The cell exhibits well-defined discharge voltage plateaus near 2 volts, a specific capacity of about 70 mA h g(-1) and a Coulombic efficiency of approximately 98 per cent. The cathode was found to enable fast anion diffusion and intercalation, affording charging times of around one minute with a current density of ~4,000 mA g(-1) (equivalent to ~3,000 W kg(-1)), and to withstand more than 7,500 cycles without capacity decay.

Active, stable and cost-effective electrocatalysts are a key to water splitting for hydrogen production through electrolysis or photoelectrochemistry. Here we report nanoscale nickel oxide/nickel heterostructures formed on carbon nanotube sidewalls as highly effective electrocatalysts for hydrogen evolution reaction with activity similar to platinum. Partially reduced nickel interfaced with nickel oxide results from thermal decomposition of nickel hydroxide precursors bonded to carbon nanotube sidewalls. The metal ion-carbon nanotube interactions impede complete reduction and Ostwald ripening of nickel species into the less hydrogen evolution reaction active pure nickel phase. A water electrolyzer that achieves B20 mA cm À 2 at a voltage of 1.5 V, and which may be operated by a single-cell alkaline battery, is fabricated using cheap, non-precious metal-based electrocatalysts.

Hydrogen evolution reaction (HER) from water through electrocatalysis using cost-effective materials to replace precious Pt catalysts holds great promise for clean energy technologies. In this work we developed a highly active and stable catalyst containing Co doped earth abundant iron pyrite FeS(2) nanosheets hybridized with carbon nanotubes (Fe(1-x)CoxS(2)/CNT hybrid catalysts) for HER in acidic solutions. The pyrite phase of Fe(1-x)CoxS(2)/CNT was characterized by powder X-ray diffraction and absorption spectroscopy. Electrochemical measurements showed a low overpotential of ∼0.12 V at 20 mA/cm(2), small Tafel slope of ∼46 mV/decade, and long-term durability over 40 h of HER operation using bulk quantities of Fe(0.9)Co(0.1)S(2)/CNT hybrid catalysts at high loadings (∼7 mg/cm(2)). Density functional theory calculation revealed that the origin of high catalytic activity stemmed from a large reduction of the kinetic energy barrier of H atom adsorption on FeS(2) surface upon Co doping in the iron pyrite structure. It is also found that the high HER catalytic activity of Fe(0.9)Co(0.1)S(2) hinges on the hybridization with CNTs to impart strong heteroatomic interactions between CNT and Fe(0.9)Co(0.1)S(2). This work produces the most active HER catalyst based on iron pyrite, suggesting a scalable, low cost, and highly efficient catalyst for hydrogen generation.

Since the discovery of carbon nanotubes (CNTs) by Iijima in 1991, [1] extensive attention has been paid to hollow tubular nanostructures because of their particular significance and prospective applications in nanometer-scale devices, chemical and biological separations, catalysis, and biological sensors. [2][3][4][5][6] Furthermore, metal nanotubes, especially magnetic-metal nanotubes, have inspired particular interest due to their intriguing electronic, optical, and mechanical properties, magnetic characteristics, and catalytic properties. [7][8][9] To date, various methods, such as thermal decomposition of precursors, [10] hydrothermal synthesis, [11] spontaneous coalescence of nanoparticles, [12] galvanic displacement reactions, [13] and electrochemical deposition, [14] have been developed to prepare tubular nanostructures. However, there have been few reports on the fabrication of magnetic nanotubes, [15,16] and the preparation methods are limited, such as thermal decomposition of precursors and surface modification of pore walls. Among these methods, the template-mediated method, using porous anodic alumina (PAA) or polycarbonate (PC) membranes initiated by Martin and co-workers [17] has proven to be a versatile approach for the preparation of ordered arrays of nanomaterials because it provides many outstanding advantages that are superior to other approaches. The resulting uniform pore diameter and length can offer an easy way to produce intact nanostructures. Until now, despite their importance in nanotechnology, only a few examples [16,[18][19][20][21] of metal nanotube fabrication have been reported, such as nickel, [16] iron, [18] and cobalt, [18] in which the pore wall of the template was chemically modified before deposition. Our previous work [16] reported a preparation method for producing highly ordered arrays of Ni nanotubes, in which the pore wall of the alumina membrane was modified with an organoamine, methyl-c-diethylenetriaminopropyl dimethoxysilane. Because organoamines easily polymerize in a moist atmosphere, the entire fabrication process needs to be undertaken with care. A facile approach for fabricating perfectly aligned metal nanotube arrays is currently of intense interest. In this paper, we report a novel method to prepare a highly ordered array of magnetic Ni nanotubes by an electrodeposition method. The outstanding features of this method are its simplicity, convenience, and effectiveness. By adding a small amount of an amphiphilic triblock copolymer such as Pluronic P123 (EO 20 PO 70 EO 20 , EO: ethylene oxide, PO: propylene oxide, Aldrich) in an electrodeposition solution (see Experimental), highly ordered arrays of Ni nanotubes can be prepared by electrodeposition. Furthermore, by adjusting experimental parameters such as the current density and electrodeposition time, the wall thickness and length of Ni nanotubes can be effectively controlled. Figure 1a shows the transmission electron microscopy (TEM) image of a Ni nanotube after completely removing the alumina membrane with a...

It is found that Cu 2+ is an effective agent for the controlled preparation of shaped gold nanoparticles. As the concentration of Cu 2+ increases from 0 mM to 0.2 mM to 1.6 mM, the shape of the gold nanoparticles changes from rod to cuboid to decahedron. A possible mechanism based on selectively retarding the growth rate of the {111} plane is proposed.

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We for the first time report the synthesis of urchinlike BiPO 4 structure composed of nanorods and its photoluminescence properties. Scanning electron microscopy (SEM) images show urchinlike BiPO 4 structure composed of nanorods. The X-ray powder diffraction (XRD) pattern indicates that the crystal structure of the nanorod is monoclinic. The high-resolution transmission electron microscopy (HRTEM) image and Fast-Fourier-transform (FFT) pattern reveal the single-crystalline nature of the nanorod. The formation mechanism was proposed. BiPO 4 displays strong blue emission. Because of the similarities of the crystal structure and lattice constants and the suitable energy level with the rare-earth phosphate, BiPO 4 is a useful host for rare-earth ions. Ln 3+ is successfully doped in BiPO 4 and an efficient energy transfer from Bi 3+ to Ln 3+ takes place, which makes BiPO 4 :Ln (Ln ) Eu, Tb, Dy) emit strong luminescence in visible region. BiPO 4 :Ln will have promising application in high-performance luminescence devices, etc.

Key words zinc oxide, morphology, controlled synthesis, flower and urchin. PACS 79.60.Jv Nanoplates, flower-like nanostructure of ZnO were successfully synthesized by employing ZnSO 4 ·7H 2 O, NaOH as the starting materials at 120°C under hydrothermal condition. Keeping the same parameters, ZnO urchin shape was obtained by addition of vitamin C at 190°C. Characterizations were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) at room temperature. Selected area electron diffraction (SAED) pattern confirms that the product is single crystalline nature. The possible formation mechanisms for synthesized ZnO nanosturcture with various morphologies have also been proposed. PL spectrum from the ZnO flower-like structures reveals weak UV emission and strong green emission.