Here, we, for the first time, synthesized Pd nanotubes covered by high-density Au-islands, in which abundant exposed Pd−Au heterojunction interfaces are present and the content of element Au can be easily controlled. The optimized nanostructures show remarkably enhanced activity for catalyzing different alcohols in alkaline media than commercial Pd/C. The mass activity is 9.66, 1.83, and 4.60 A mg metal −1 toward the electrooxidation of ethanol, glycerol, and ethylene glycol in alkaline media, which is about 6, 4, and 7 times that of Pd/C, respectively. Additionally, a model was proposed to explain the relationship between the structure and the catalytic activity.
Wavy palladium (Pd) nanorods were obtained by controlled synthesis by using amine-boranes as the reducing agents. Thanks to the unique structure and strong interaction with graphene, the as-synthesized Pd nanorods supported on graphene exhibit much enhanced electrocatalytic activity towards formic acid oxidation as compared with Pd nanoparticles.
We report a facile strategy to tune the growth behavior and surface structures of Pt nanocrystallites by varying the concentration of oleylamine (OAm) in mixed solutions of OAm and octadecene (ODE); the resulting Pt nanorods (NRs) and nanodendrites (NDs) show superior electrocatalytic performance for the oxygen reduction reaction (ORR). Long wormlike NRs with uniformly small diameters and NDs branched with NRs were obtained at low and medium concentrations of OAm, respectively. Time‐dependent morphology measurements showed that small Pt nanoparticles (NPs) were initially formed, which evolved into NRs or NDs depending on the reaction kinetics for Pt atom formation. Benefiting from the selective exposure of the ORR‐active (111) facet, the wormlike Pt NRs exhibited significantly higher ORR activity and electrochemical stability than state‐of‐the‐art Pt NP catalysts, which are enclosed with both the (111) and (100) facets. The ORR activity and stability of these catalysts were further enhanced by forming Pt NDs, probably as a result of the fact that the NR‐interconnected architectures produce more‐active high‐index facets in the junction areas.
Supercapacitors are one of the most promising energy storage devices, which could be used in hybrid vehicles, portable electronics and other pulse-power applications. Electrodes however play a crucial role in determining the performance of supercapacitors and current study mainly focused on transition metal oxides/nitrides and conducting polymers that show a large pseudo-capacitance in repeated charging-discharging profiles. Among these materials, the vanadium nitride (VN) possesses a high specific capacitance and chemical stability and is metallic in nature. VN, however, is often made in powder form and must combine with polymer to form electrode. In this case, conductivity and ionic accessibility, due to polymer addition, are reduced and capacitance also decreases at high voltage scan rates. In this work, the carbon nanotubes (CNTs) are electrochemically coated onto nickel mesh and sol-gel technique is then used to deposit V2O5 onto tube coatings, followed by calcining composite under anhydrous ammonia atmosphere. The morphology and structural properties of electrode are characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman measurement, and X-ray photoelectron spectrometer (XPS). A three-electrode system is employed to study the electrochemical behavior, including cyclic voltammetry (CV), galvanostatic charge–discharge cycling (CD). The experimental results suggest that CNTs provide an open mesoporous texture for access of electrolytes and conductive path for electron transfer to Ni collector.
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