Abstract
Novel nanocomposites of carbon nanotubes supported porous VOxNy nonoribbons (VOxNy-CNTs) have been synthesized by the annealing of the sol-gel mixture of CNTs and V2O5 under NH3 atmosphere as well as the ageing process in air. Besides the morphological and structural characterizations revealed by TEM, SEAD, EDS, XRD and XPS measurements, typical electrochemical tests including cyclic voltammetry (CV), rotating disk electrode (RDE) and chronoamperometry have been employed to determine the oxygen reduction reaction (ORR) performance of VOxNy-CNTs. Inspiringly, the results indicate that VOxNy-CNTs catalyst exhibits a 0.4 mA/cm2 larger diffusion-limited current density, a 0.10 V smaller onset potential value, a 10.73% less of ORR current decay and an excellent methanol-tolerance compared with commercial Pt/C catalyst. Therefore, we have reasonable grounds to believe that this new VOxNy-CNTs nanocomposites can be regarded as a promising non-precious methanol-tolerant ORR catalyst candidate for alkaline fuel cells.
Highlights
Lithium-ion batteries (LIBs), dye-sensitized solar cells (DSSCs) and electrochemical capacitors (ECs)[10,11,12,13,14,15,16], due to the unique physical and chemical properties such as high intrinsic conductivity, relatively good electrochemical stability as well as the Pt-like electrocatalytic activity
As for VOxNy-CNTs composites, VOxNy nanoribbons with a few tens of nanometers in widths and lengths up to micrometer range are randomly supported by plentiful tortuous CNTs
This result can be ascribed to the penetration of oxygen atoms into the VN crystal lattice[17], which happened once the prepared samples were taken off from the furnace
Summary
Lithium-ion batteries (LIBs), dye-sensitized solar cells (DSSCs) and electrochemical capacitors (ECs)[10,11,12,13,14,15,16], due to the unique physical and chemical properties such as high intrinsic conductivity, relatively good electrochemical stability as well as the Pt-like electrocatalytic activity. To further enhance the electrochemical properties of VOxNy powders, Chen and his coworker synthesized carbon-supported VOxNy nanocrystalline using a mixture of melamine and V2O5 xerogel as precursor and obtained a specific capacitance of 273 F/g in 1M KOH at the scan rate of 30 mV/s20. Shu et al developed a soft-template synthesis of VOxNy-C nanomaterials for supercapacitors with a maximum specific capacitance of 271 F/g at 1A/g using ployvinylpyrrolidone (PVP) as the template and V2O5 xerogel as vanadium source Their results demonstrated that the intimate contact between VOxNy grains and remaining carbon will result in a better electronic conductivity and the larger surface area will furnish more surface active redox sites[21]. We have successfully synthesized novel CNTs-supported porous VOxNy nanoribbons composites with an improvement of structural features as efficient and durable non-precious ORR catalysts in alkaline electrolyte using V2O5 nanoribbons and CNTs as raw materials
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