Core-shell Ag@Pd Nanoparticles And Pd Hollow Nanospherses:Controllable Preparation, And Performance Of Electrocatalytic Properites

Due to population and economic growth, the rapid development of industrial and agricultural production,not only increasing the annual energy demand,but also global warming and environmental pollution is getting worse. Energy conservation, environmental protection, looking for renewable energy,advocate changing production and lifestyle,adhere to sustainable development, increasingly widespread attention, inspired a lot of people on alternative energy research.Fuel cells have many advantages such as,less environmental pollution, excellent safety performance, low noise and high efficiency, which attracted widespread attention of domestic and abroad in recent years.Based on the problems of direct methanol fuel cell (DMFC),people find out a new alternative fuel - formic acid.Direct formic acid fuel cell (DFAFC) has non-toxic, easy storage, excellent electrochemical oxidation performance,high energy density and low temperature performance, etc.he study found that although palladium catalyst has the best catalytic activity and antitoxic performance for acid anodizing,however, its stability is poor,it is more easily oxidized than other Pt-based metals, as the reaction proceeds,it may result in failure or reduced activity.The porous, multi-dimensional and multi-level hollow nanospheres sphere which constructed by Pd clusters,has superior structural stability,durable small size effect" and quantum size, high surface area and high electro-catalytic activity.In order to reduce the amount of Pd catalyst,enhance its catalytic activity and the efficiency,Pd-based transition metal anode catalyst material can be developed into a corresponding hollow nanospheres. It is noted that,Se located in oxygen species,its nature is lively,and forms to selenide formation with Pd, Ru and other transition metals.Makes it difficult to synthesize Pd-based transition metal hollow nanospheres that we need.It is therefore necessary to find a more suitable template than selenium sol.Our experimental group use method of reference,first synthesized silver sol;Then use silver sol as a template which relatively inert than selenium sol,synthesized a series of different sizes, different shell thickness Pd hollow nanospheres and modified glassy carbon (GC) electrode (Pd hollow/GC). Formic acid as a probe molecule to study Pd hollow/GC electrode catalytic oxidation of formic acid,open up new avenues for preparation of small organic molecules of the fuel cell anode catalyst material.Preliminary results are as follows:1、At a temperature of about 18℃, to provide a solution in three times water,AgN03 as precursor, polyvinyl pyrrolidone (PVP) as a surface active agent, ascorbic acid as a reducing agent,different particle size silver sol were regulated and synthesized by adjusting the dose of NaOH.2、At room temperature,silver sol as a template, ascorbic acid as a reducing agent, by changing the amount of substance ratio between silver and palladium successfully synthesized the different particle size of Ag@ Pd solid nanoparticles.3、Soaked with concentrated aqueous ammonia to remove silver template, obtained Pd hollow containing residual silver. Scanning electron microscopy (SEM) to detect surface morphology of core-shellstructure of Ag@ Pd solid nanoparticles and Pd hollow;High-resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) to detect structure and composition of Pd hollow.The results showed that the particle size of the Pd hollow nanospheres are uniform,monodisperse is good, spherical shell surface is rough, they are constructed by a number of Pd clusters,the structure is polycrystalline Pd with not high crystallinity.4、Using cyclic voltammetry (CV) and chronoamperometry (i-t) conventional electrochemical methods, in sulfuric acid, sodium hydroxide and other different supporting electrolyte,we studied Pd hollow modified glassy carbon (GC) electrode (Pd hollow/GC) electro-catalytic oxidation for methanol, formic acid, formaldehyde.The results showed that Pdhollow barely has noticeable catalytic properties on methanol and formaldehyde, but its electrocatalytic activity for formic is highest and superior to electro-deposition Pd.To do a more systematic comparison for different particle sizes and thick shell of Pdhollow catalyzed acid properties,provides a theoretical basis for further optimization of the direct formic acid fuel cell research.