Single-crystal ZnO nanorod/amorphous and nanoporous metal oxide shell composites were facilely prepared by electrochemical deposition and tested as promising electrode materials for supercapacitor applications.Because of the depleting energy sources and increasing environmental concerns, supercapacitors as alternative energy/power sources have attracted much interest because they have high power density compared to batteries and high energy density compared to conventional capacitors and can be deeply discharged without any deleterious effect on lifetime. 1-3 In this field, designing a new electrode material with high specific capacitance and long-term cycle stability has become one of the most important research focuses. 4,5 At present, a nanoscale approach to supercapacitor electrode has received great interest because of the unique properties of nanostructures leading to the improved performances. 6 One dimensional (1D) nanostructures have been widely studied because they can provide short diffusion path lengths for ions, leading to high charge/ discharge rates. 7,8 However, one of the challenging issues is to tackle their capacity decay with cycling, resulting from the collapse of nanostructures. In addition, the electronic conductivity of metal oxide is generally poor, and it obviously affects their high performances for supercapacitor applications. In order to overcome the above shortcomings, carbon-based materials are widely utilized as supports because of their large surface area and high electrical conductivity. 9 Such investigations are intended to balance the cost and the performances of supercapacitors. In addition, the carbon-based supports possibly encounter severe corrosion in the electrochemical window of some metal oxides via eqn (1). 10 C + 2H 2 O / CO 2 + 4H + + 4e À (0.207 V vs. NHE, 25 C) (1) Electrochemical corrosion of carbon-based supports will cause the agglomeration of metal oxides coated on the surfaces of supports. In addition, the corrosion of carbon-based supports will lead to electrically isolated metal oxide particles that are detached from the supports. These effects will result in rapid degradation of the electrochemical performances of metal oxide electrodes. Therefore, it will be desirable to use more robust noncarbon supports to avoid the corrosion of supports and prevent agglomeration of metal oxides. 11 Since 1D single-crystal ZnO nanorod is one of the most attractive functional semiconductor materials and has a small capacity, so it can function as efficient mechanical support and electron conducting pathway because of its high chemical stability, conductivity, and It is well accepted that the nanostructured electrodes with large specific surface area, amorphous and nanoporous configuration can greatly improve the electrode/electrolyte contact area, shorten the diffusion path of current carriers, and enhance the electron conduction in electrodes. However, the poor electronic conductivity of amorphous and nanoporous metal oxides usually affects their high performances in s...

Pt as one of the most promising electrochemical catalysts has attracted much attention because of its superior electrochemical performance. A facile electrochemical route was utilized to synthesize Pt nanorods aggregates at room temperature. The morphologies and structures of the prepared Pt deposits were characterized by scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometer (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The electrocatalytical activities of Pt nanorods aggregates were evaluated using methanol as model molecules. Pt nanorods aggregates showed highly improved electrocatalytical activity toward methanol oxidation compared with Pt nanoparticles aggregates and commercial Pt. The present method provides a new and facile strategy toward the synthesis of nanorods aggregates of noble metals with extensive applications.

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