Synthesis Of High-performance Platinum-based Catalysts And Investigation Of Its Electrocatalysis

Fuel cell,a device which can convert chemical energy to electricity directly,is a new generation of clean energy resource,which has many advantages including: good efficiency,high working current density,light weight,small volume,long lifetime,quick launch,varieties source of fuel and environmental friendly.It is considered as the alternative to conventional fossil energy.The Pt-based electrocatalyst is the most widely used in fuel cell.Due to the rare storage of Pt,causes its high price.The usage of Pt-based eletrocatalyst makes its high cost and sets the obstacle against commercial process.The crucial techniques to decrease the cost of fuel cell are developing high-performance Pt-based electrocatalyst,reducing the loading of Pt and raising the utilization ratio of Pt.In this dissertation,the support effect and the alloy effect in nanoparticles have been took out to increase the electrocatalytic activities and durability.The geometry,particle size and surface composition were studied by transmission electron microscope(TEM),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The electrochemical properties were studied by cyclic voltammetry(CV),linear sweep voltammetry(LSV)and CO stripping method.Firstly,2-Dimension Nitrogen Ordered Mesoporous Carbon(NOMC-2D)and 3-Dimension Nitrogen Ordered Mesoporous Carbon(NOMC-3D)are as the supports respectively to study the supports' effect to methanol oxidation activity and the anti-poisoning ability in Pt-based catalyst.The NOMC-2D supports are flat structure with high specific surface area,containing many oxygen-abundant functional groups that have eletrocatatlytic activity.The flat structure of NOMC-2D supports make the Pt nanoparticles have lager practical contact whit the supports,which leads the stronger interaction than the NOMC-3D supports.The as-prepared Pt/NOMC-2D is better than Pt/NOMC-3D and commercial Pt/C catalyst in methanol oxidation activity and anti-poisoning ability.Secondarily,two kinds of different Pt mass fraction eletrocatalysts were synthesized to study the effect of Pt mass fraction toward the catalysis of methanol oxidation in Pt-based electrocatalyst.In the condition of 30 % Pt mass fraction,the Pt nanoparticles are aggregation and less interaction with supports,which makes it poorer methanol oxidation activity and anti-poisoning ability than 10 wt.% Pt mass fraction eletrocatalyst.Finally,the transition metal Ni was introduced by chemical reduction method to form the Pt-rich-layer Pt-Ni/XC-72 eletrocatalyst.In order to improve the catalysis for oxygen reduction and optimize the binding energy between Pt and intermediate product(e.g.-OOH and-OH),the d-band center of Pt was modulated by lattice contraction and ligand effect.The as-prepared PtNi2/XC-72 shows considerable higher oxygen reduction activity than commercial Pt/C catalyst.