Comparative evaluation of hydrogen storage behavior of Pd doped carbon nanotubes prepared by wet impregnation and polyol methods

• Large scale synthesis of MW-CNT using CVD method.
• Dispersion of Pd on MW-CNT using different routes.
• Polyol method shows better hydrogen storage capacity.
• Higher dispersion of Pd leads to better hydrogen sorption.

The present manuscript deals with the hydrogen absorption properties of multiwalled carbon nano-tubes (MWCNTs) doped with Pd nanoparticles by the conventional wet impregnation method and the polyol method. In the latter method Pd nanoparticles are doped into CNTs based on polyhydroxy organic compounds (polyol) mediated functionalization. The polyol medium reduces palladium chloride to palladium nanoparticles, and also acts as a capping agent to stabilize the Pd nanoparticles. The samples have been characterized using X-ray diffraction (XRD), Energy Dispersive X-ray (EDX) and Infrared (IR) spectroscopy. Hydrogen absorption studies clearly illustrate that Pd doped MW-CNT's prepared by polyol mediated functionalization show much higher hydrogen storage capacity compared to the sample prepared by wet impregnation route. To determine the cause of this behavior, Transmission Electron Microscopic (TEM) studies of the samples were carried out. The results indicate that the dispersion of Pd nanoparticle on the MW-CNT is much better for the sample prepared by the polyol route. An attempt was made to determine the existence of any metal-support interaction using Thermogravimetric Analysis (TGA). The investigation reveals that the higher dispersion of Pd nanoparticles on the CNT support plays a major role for the hydrogen adsorption.

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