Highly Dispersed Pt-Au/rGO Catalysts Prepared by Hyperbranched Polyglycerols for Efficient Electrooxidation of Methanol

Recently, fuel cells especially direct methanol fuel cells (DMFCs), have attracted great interest because of their high energy density, their pollution-free operation mode and thus their prospect for use in convenient transportation. Although platinum (Pt) catalyst is an efficient catalysts for DMFCs, it has some problems such as high price, poor stability and durability. Therefore, the research of high performance Pt catalysts becomes the focus. Firstly, the hyperbranched polyglycerols (HPG) were synthesized by the one-step anionic ring-opening polymerization. The Pt-Au bimetallic catalysts supported on reduced graphene oxide (Pt-Au-HPG/rGO) were synthesized via a hydrothermal method, using HPG as the template and stabilizer. The electrocatalytic performances for the electrooxidation of methanol were investigated by electrochemical methods. Compared with commercial Pt/C (10 wt %) catalysts, Pt-Au-HPG/rGO has the larger electrochemically active surface area (ECSA, 108.8 m(2) g(-1)), higher catalytic performance (0.498 A mg(metal)(-1)) and better stability. This excellent performance is attributed to the good dispersion and conductivity of Pt-Au-HPG/rGO for the addition of HPG, rGO and Au. Meanwhile, the bifunctional and electronic effects between Au and Pt improved the electrochemical performance of the samples.