Electro-catalytic activity of multiwall carbon nanotube-metal (Pt or Pd) nanohybrid materials synthesized using microwave-induced reactions and their possible use in fuel cells

Abstract

Microwave induced reactions for immobilizing platinum and palladium nanoparticles on multiwall carbon nanotubes are presented. The resulting hybrid materials were used as catalysts for direct methanol, ethanol and formic acid oxidation in acidic as well as alkaline media. The electrodes are formed by simply mixing the hybrids with graphite paste, thus using a relatively small quantity of the precious metal. We report Tafel slopes and apparent activation energies at different potentials and temperatures. Ethanol electro-oxidation with the palladium hybrid showed an activation energy of 7.64 kJmol−1 which is lower than those observed for other systems. This system is economically attractive because Pd is significantly less expensive than Pt and ethanol is fast evolving as a commercial biofuel.

Palladium and palladium–tin supported on multi wall carbon nanotubes or carbon for alkaline direct ethanol fuel cell

“…Thus, supposing that the voltammetric area of the curve over the hydrogen desorption peak (in desorption/adsorption hydrogen region) is numerically equal to the charge of a monolayer of hydrogen deposited on the active electrocatalyst surface and assuming that the charge for monolayer adsorption/desorption of hydrogen on Pt is 210 mC cm À2 . It is possible to determine the active surface area available for the hydrogen adsorption on Pt, but, in alkaline environment, it is not reasonable to derive the Pd ECSA electrocatalyst from the hydrogen region, since Pd is known to efficiently absorb hydrogen, which can diffuse into the Pd bulk, to form Pd hydride rather than adsorbing onto the Pd surface [34,8]. Thus, in alkaline environment with Pd electrocatalyst, the ECSA is estimated using the area over the voltammetric curve in the palladium oxides reduction peak region.…”

PtPdNi Catalysts Supported on Porous Carbon for Ethanol Electro‐oxidation

“…The apparent activation energies for the overall reaction at −0.3 V and −0.2 V were 7.8 and 9.1 kJ mol −1 for PtPdNi/CMK‐3, 6.7 and 8.9 kJ mol −1 for PtPdNi/a‐BC, 5.2 and 6.4 kJ mol −1 for PtPdNi/b‐BC and 14.1 and 15.7 kJ mol −1 for PtPdNi/Vulcan. These values are very similar to those reported for the EOR reaction on PdNi/C and PdNiAu/C electrodes, and on a Pd/MWCNTs catalyst . The most remarkable result to emerge from the data is that the carbon support has an important influence on the overall ethanol oxidation reaction.…”

Temperature dependent performance and catalyst layer properties of PtRu supported on modified few-walled carbon nanotubes for the alkaline direct ethanol fuel cell

“…All the catalyst passivate during the CV meaning that the current at 0.5 V on the positive sweep is lower than on the negative sweep due to poisoning at low potentials by reaction intermediates as well as the cleaning of the surface by oxidation at high potentials [42]. has generally been determined between 10 and 25 kJ mol -1 on Pt [44][45][46][47][48][49] and a decrease has been reported with the addition of Ru in acidic media [38]. Thus, the values we have determined are in line with the previous findings.…”