One-pot synthesis of highly efficient graphene based three-dimensional hybrids as catalyst supporting materials for electro-oxidation of liquid fuels†
The electrocatalytic oxidative performance of fuels like methanol, ethylene glycol, formaldehyde and formic acid mainly depends on the electrode surface which in turn has applications in energy generating systems like fuel cells. The surfaces should have selectivity, stability and low onset potentials (high kinetics for the electro-oxidation). We synthesized high quality few-layered graphene by simple and fast electrochemical exfoliation of graphite rods using poly(3,4-ethylenedioxy thiophene)–poly(styrenesulfonate) (PEDOT:PSS) as an effective electrolyte, which was further used for the synthesis of graphene–MWCNT hybrids. Pt decorated composites were synthesized by reduction with sodium borohydride. These composites were characterized using X-ray diffraction spectroscopy, Raman spectroscopy, FT-IR spectroscopy, UV-visible absorption spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy and high-resolution transmission electron microscopy. The electrochemically active surface area of the graphene–MWCNTs/Pt, MWCNTs/Pt and graphene/Pt modified catalysts was calculated to be 88.76, 38.41 and 14.6 m2 g−1, respectively. The performance of Pt decorated modified electrode catalysts towards the oxidation of liquid fuels was studied using cyclic voltammetry, linear sweep voltammetry and chronoamperometry in acidic media. The oxidation efficiency of liquid fuels on graphene–MWCNTs/Pt was also explained and it follows the order: formaldehyde > methanol > ethylene glycol > formic acid, in the decreasing order of oxidation efficiency.