Research On The Synthesis Of 1 Dimensional Pt Based Alloy Nanometer Materials And Their Electro-catalytic Performance

Platinum?Pt?is currently the best catalyst for fuel cells.Nevertheless,the low reserves,high cost and poor long-term duration of Pt restrict its application as a catalyst.Therefore,the development of highly active,stable and low-cost catalytic materials will contribute to their wide application of in fuel cells.Researches have shown that the morphology,structure,composition and surface state of the catalyst have great influence on its performance.By adding one or more kind of metals into Pt catalyst to form a binary or multi-component alloy,the electrocatalytic activity and stability can be enhanced via heteroatom interactions.In this dissertation,binary Pt-Cu and ternary Pt-Pd-Cu alloy nanowire networks were successfully prepared by chemical co-reduction method and solvothermal method,respectively.The morphology,structure and composition of the Pt-Cu and Pt-Pd-Cu alloys were characterized by the multiple detection techniques,such as TEM,XRD,EDS.The electrocatalytic properties of Pt-Cu and Pt-Pd-Cu alloys were studied by electrochemical test method.The main results are as follows:?1?Pt-Cu nanowires were successfully prepared by using NaBH₄ as a reducing agent at room temperature for 1 h,at 600 rpm.The composition of Pt-Cu was controlled by linearly adjusting the ratio of Pt/Cu in the precursor.The obtained Pt-Cu nanochain is an face-centered cubic alloy phase structure with a diameter of 5-8 nm.?2?Electrocatalytic activity of Pt-Cu alloy nanowires is correlative with its composition.For ethylene glycol in alkaline solution,Pt₃₃Cu₆₇ exhibits the best electrocatalytic performance and stability with a mass current density reaching to 3.1A?mg_Pt^-1.?3?The prepared Pt-Pd-Cu face-centered cubic alloys are mutual interconnection,with a network-like structure.The diameter of nanowires is 12±3 nm.Strong interactions are found between the three metals,which can adjust the electronic structure and thus improve the performance of the catalyst.?4?After the analysis of synthesis mechanism of Pt-Pd-Cu nanowire networks,we found that the formation of the wire network origins from the interactions between PVP and Br^-,which selectively adsorb to different crystal planes to guide the anisotropic growth of metal nanowires.Br^-can also reduce concentration of metal precursors in a solution and accordingly change the reduction potentials.?5?For the Pt-Pd-Cu nanowire networks as a cathode catalyst participate in the oxygen reduction reaction,the electrocatalytic performance can reach 0.64 A?mg_Pt^-1at 0.9 V_RHE,which is 4.7 times higher than that of commercial Pt/C.After 10,000cycles of accelerated endurance test,its mass activity only reduce by 17%.As a anode catalyst involved in the electrocatalytic oxidation of ethanol,the mass activity of Pt-Pd-Cu nanowire networks reaches to 2974 mA?mg_Pt^-1,presenting a 2.44-fold enhancement relative to the commercial Pt/C.In addition,the Pt-Pd-Cu networks possess excellent antipoisoning ability.Through forming one-dimensional nanostructure alloy material with inexpensive transition metals,the obtained Pt-Cu and Pt-Pd-Cu alloy nanowires exhibit excellent electrocatalyst activity with better mass&electron transport capabilities,which are promising fuel cell catalyst.