Preparation And Application Of Hollow/Porous Precious Metal Nanoparticles

As the energy crisis becomes more serious,direct methanol fuel cells?DMFCs?have attracted wide attention due to their advantages such as direct use of fuel,simple battery structure,and high efficiency.Platinum is currently the most commonly used catalyst to catalyze the oxidation of methanol,but the cost is high and the stability is low.Therefore,the design of a novel platinum-based catalyst with high activity and high stability has a profound effect on reducing platinum loading and increasing platinum utilization.At present,hollow/porous precious metal nanostructures as a new type of catalyst have the advantages of low density,large specific surface area,good connectivity,high stability,and have a good application prospect in improving the performance of catalyzing methanol oxidation.This paper mainly studied on the morphology and composition of nanoparticles,explored the growth mechanism,and studied the property of catalyzing methanol oxidation.The main contents are as follows:1.Hollow dendritic Ag/Pt alloy nanoparticles were synthesized by a double template method:Ag nanoparticles as the hard template to obtain hollow spheres by a galvanic replacement reaction between PtCl₆^2-and metallic Ag and surfactant micelles?Brij58?as the soft template to generate porous dendrites.We studied the effects of the Ag/Pt ratio,surfactant and reaction temperature on the morphology.In addition,we explored the formation process of hollow dendritic Ag/Pt nanoparticles by tracking the morphologies of the nanostructures formed at different stages.We found that these Ag/Pt alloy nanoparticles exhibited high activity(440 mA·mg^-1)and stability as an electrocatalyst for catalyzing methanol oxidation.2.Dendritic Pt/Cu nanoparticles were synthesized by a one-step method with the help of surfactant Brij58 at room temperature and we also studied the effects of different Pt/Cu ratios on the morphology and size of nanoparticles.In addition,we further tuned the morphology of the Pt/Cu nanostructures by introducing bromide ions,eventually leading to the appearance of some tripod-like structures.Compared with dendritic Pt/Cu and commercial Pt black,these tripod-like Pt/Cu nanostructures exhibited higher electrocatalytic activity and CO tolerance for catalyzing methanol oxidation.3.Silica spheres were used as hard templates whose surface were modified by amino group.A layer of porous dendritic metal shell were grown on the surface of silica spheres under the action of surfactant Brij58.After etching with sodium hydroxide solution,hollow porous nanospheres were finally obtained.The influence of surfactant on the morphology and the growth mechanism were explored.The performance of catalyzing methanol oxidation by hollow porous nanospheres was investigated.