Preparation And Study Of Pt-Bi Cathode Catalysts Of Direct Methanol Fuel Cell

Direct methanol fuel cell (DMFC) is an ideal power source due to its high energy density, convenient fuel management and low system complexity. Even though it is applicable for a large variety of technical area, the commercial application of DMFC was limited due to methanol crossover and catalytic inefficiency. In this work, the bulk Pt1Bi1 intermetallic compound was prepared by high temperature argon arc melting method to be used as the cathode catalysts of DMFC for the first time. According to the result of cyclic voltammetry and rotating disk electrode, we found out that this kind of Pt1Bi1 electrode exhibits excellent catalytic properties of oxygen reduction reaction (ORR) and methanol-tolerant. In ordered intermetallic Pt1Bi1, the Pt-Pt bond length is increased to 4.32?. This expansion makes it very difficult for methanol and CO to be adsorbed on the Pt1Bi1 surface, which makes that Pt1Bi1 has the ability of methanol-tolerant. X-ray photoelectron spectroscopy analysis indicated an increased d-electron vacancy of the Pt in Pt1Bi1 which may be the reason for increasing the current density of ORR. We prepared the Vulcan XC-72 carbon-supported nano-Pt-Bi intermetallic compound by Sol method for the first time. The Pt-Bi intermetallic compound exhibited excellent catalytic properties of ORR and methanol-tolerant. The optimum synthesis conditions were obtained by orthogonal experiments. The Pt-Bi/C catalysts synthesized in resulting solution with different Pt/Bi initial atomic ratio were characterized by XRD, TEM, XPS, EXAFS, and all can be characterized as Pt1Bi2 intermetallic compounds with a typical character of cubic phase. The Pt-Pt bond length becomes longer due to the addition of Bi, which makes it very difficult for methanol and CO to be adsorbed on the Pt1Bi2 surface, so Pt1Bi2 is methanol-tolerant. X-ray photoelectron spectroscopy analysis indicated an increased d-electron vacancy of the Pt in Pt1Bi2 intermetallic compound. The increase of 5d vacancies will induce an increased 2Ï€electron donation from O2 to the Pt, resulting in an increased O2 adsorption and a weakening of the O-O bond.