Research On The Morphology Of Platinum Nanoparticles And Their Electrochemical Performance

Nowadays,we achieve a mount of goal’s in science and technology.However,we are not only enjoy benefit convenience from the science and alsosuffering the problem.After the Industrial Revolution,a large number of fossil fuelalready continuously developed and using,at the same time,the fossil fuel also broughta lot of problem.For example,it is veryharmful for the environment because it can produces a large number of harmful gases to pollute the environment during of the burning.Fuel cell is a new type of energy that can reduce energy consumption,reduce pollutant emissions,and reduce reliance on traditional fossil fuels.A large number of researchers are working hard to promote and develop the technology of fuel cell.The latest data show that the fuel’s factory cost already lower than past at 35%.Compared with traditional internal combustion engine,its manufacturing cost is still twice as high as that of internal combustion engines.At present,the biggest obstacle to commercialization of fuel cells still comes from cathode catalyst Pt electrode materials.When Pt is chosen as the cathode catalyst,on the one hand,its resources are scarce and its price is high.At the same time,it is easy to lose the activity of carbon monoxide poisoning in the catalytic process,resulting in the low catalytic activity of oxygen reduction,which is the bottleneck of the development of fuel cell.How to reduce the amount of Pt and improve the efficiency of catalytic activity of Pt cathodic oxygen reduction is one of the key problems in the field of experimental research and synthesis.In this paper,the dendritic platinum nanoparticles were synthesized by liquid phase reduction at lower temperature in the inorganic aqueous phase system.The mild reductant formic acid was selected and pluronic was added as surfactants.The effect of different technological parameters on the morphology of dendritic nanoparticles was discussed.The morphology evolution of dendritic nanoparticles was observed by using TEM as the main means of characterization.The formation mechanism of dendritic nanoparticles was also discussed.The structure inducement of surfactants in pure water phase system is an important factor influencing the formation of dendritic platinum nanostructures.The surfactants it will play a role of directional selection under the reduction of zero-valent platinum formic acid.Finally the morphology of platinum nanoparticles will be dendritic.When the concentration of precursor in the reaction system is constant,with the increasing of reaction temperature,the dendritic platinum nanoparticle can form serious reunion.The best reaction temperatureat 50℃,the size of the dendritic platinum nanoparticles is about20³0nm and can keep good dispersivity.Meanwhile,if the reaction system at more acid condition,the hydrogen ions can inhibit the reduction of platinum ions.At PH=3,only a small amount of platinum nanoparticles are reduced,and no branching is formed.At a certain temperature and a certain concentration of surfactants,the concentration of precursor decreases will affect the size of the resulting dendritic platinum nanoparticles,under the concentration potassium chlorite solution is75mmol/L,the final reduced dendritic platinum nanoparticles are about 3⁵nm.Based on the synthesis of dendritic platinum nanoparticles,a platinum carbon catalyst was prepared by loading dendritic platinum nanoparticles on XC-72R.The electrochemical properties of dendritic platinum nanoparticles were studied,and the effect of dendritic platinum nanoparticles on electrochemical activity was also been discussed.The electrochemical properties of the dendritic platinum nanoparticles were tested on XC-72R,the results showed that the surfactant would affect the electrochemical performance test,and the surfactant would cover the platinum particle surface,which would affect the exposure of the crystal surface.The initial reduction potential of the ORR curve is 0.59 V,the half-wave potential is 0.29 V,and the limit current density is 2.64m Acm^-2.Without the add of surfactant,the dendritic platinum nanoparticles catalyst can be prepared by direct impregnation reduction method.Compared with the system containing surfactants,the morphology of dendritic platinum nanoparticle’s branch will form disunity.The best comprehensive electrochemical performance is that the reaction time is 24min,the initial reduction potential of the ORR curve is 0.78V,the half wave potential is 0.59V,and the limit current density is 3.77m Acm^-2.Formic acid not only exists as a reductant,but also acts as a structural inducer.The carboxyl group it contains is adsorbed on the surface of platinum.And Platinum’s crystal plane（111）The binding energy of the crystal plane with-COOH is the lowest.Finally,the dendritic platinum nanoparticles are formed.