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Investigation of Nb2O5/Graphene Supported Platinum-Cobalt Nanocomposite as Electrocatalyst for the Alkaline Alcohols Fuel Cells

Tuesday, 7 October 2014: 15:40
Sunrise, 2nd Floor, Star Ballroom 8 (Moon Palace Resort)
V. Kepeniene, J. Vaiciuniene, R. Kondrotas, V. Pakstas, L. Tamasauskaite-Tamasiunaite, and E. Norkus (Center for Physical Sciences and Technology)
In the present work, niobium oxide/graphene supported PtCo catalyst with the Pt:Co molar ratio 1:7 (denoted as PtCo(1:7)Nb2O5/GR) was fabricated by means of the rapid microwave heating polyol method. The surface morphology, structure and composition of the synthesized catalyst were examined by transmission electron microscopy, X-ray diffraction and inductively coupled plasma optical emission spectroscopy. The electrocatalytic activity of the synthesized catalyst towards the oxidation of alcohols – ethanol, methanol and ethylene glycol in an alkaline medium was investigated by means of cyclic voltammetry and chronoamperometry.

It has been determined that the Pt loadings was 0.285 mg Pt cm–2 in the synthesized PtCo(1:7)Nb2O5/GR catalyst. For comparison, the bare commercial Pt/C (Sigma-Aldrich) catalyst with 10% wt. Pt with the Pt loading of 0.385 mg Pt cm–2 was used. The electroactive surface areas (ESAs) of the prepared and commercial catalysts were determined from the cyclic voltammograms of PtCo(1:7)Nb2O5/GR and Pt/C catalysts recorded in a deaerated 0.5 M H2SO4 solution at a sweep rate of 50 mV s–1by calculating the charge associated with the hydrogen adsorption.

According to the data of TEM analysis, the Pt nanoparticles of ca. 1-2 nm in size were successively deposited onto the surface of graphene nanosheets.

It has been found that niobium oxide/graphene supported PtCo catalyst with the Pt:Co molar ratios 1:7 show an enhanced electrocatalytic activity towards the oxidation of alcohols in an alkaline medium as compared with that of 10% wt. Pt implicated commercial Pt/C catalyst. Alcohols oxidation current densities were found to be ca. 3 – 40 times higher at the PtCo(1:7)Nb2O5/GR catalyst in comparison with those at the commercial Pt/C catalyst. The prepared catalyst seem to be a promising anodic material for direct alcohols fuel cells.

Acknowledgement

Postdoctoral fellowship is being funded by European Union Structural Funds project ”Postdoctoral Fellowship Implementation in Lithuania”.