Modification Of Graphene/Platinum Nanocomposites And The Study Of Their Electrocatalytic Performance

To achieve the widespread commercialization of direct methanol fuel cells,the anode catalyst performance should be further improved.Graphene has been considered as a promising catalyst carrier for its large specific surface area and good electrical conductivity.Since the advent of graphene,research workers have payed extensive attention on it.Using graphene as catalyst carrier,this article mainly includes the following two parts:N-doped TiO₂ nanotubes were prepared using hydrothermal method and heat treatment,and then they were used as additives to the preparation process of graphene/platinum-based catalyst.The final product was Pt/G-NT nanocomposite.Pt/G-T was prepared using non-doped TiO₂ nanotubes as additives and Pt/G-A was prepared without TiO₂ nanotubes added into the synthesis process.Electrochemical tests showed that Pt/G-NT catalyst had higher electrochemical active surface area,which was up to 68m2/g Pt.The cyclic voltammetry curve in 0.5 mol/L H₂SO₄ containing 0.5 mol/L CH₃OH solution showed that its forward scan current density was 446.8 mA/mg Pt,which was much higher than those of Pt/G-T and Pt/G-A.The current density of Pt/G-NT in chronoamperometry test remained higher level than Pt/G-T and Pt/G-A,proving its good performance for methanol oxidation and good stability.Using N-doped TiO₂ nanotubes as additives could improve the dispersion of platinum nanoparticles and the characteristics of graphene,thus promoting the catalytic performance of graphene/platinum-based materials.MoS₂ nanosheets were prepared by chemical exfoliation of bulk MoS₂ and then added to the preparation process of graphene/platinum-based catalyst in which graphene oxide,chloroplatinic acid and copper nitrate were used as precursors.The as prepared nanocomposite was denoted as M-PtCu/G.M-Pt/G without copper and Pt/G-B without MoS₂ nanosheets and copper were prepared using similar method.Their characterizations and electrochemistry tests were carried out.Electrochemical test showed that the methanol oxidation current peak density of M-PtCu/G reached 792.9 mA/mg Pt.The current density of M-Pt Cu/G in chronoamperometry test remained stable,demonstrating improvedperformance for methanol oxidation and good stability.The promoted performance of M-PtCu/G was attributed to the addition of MoS₂ nanosheets and the alloying of platinum and copper.