Preparation And Properties Of One-dimensional Platinum-based Nanostructured Oxygen Reduction Catalyst

Nowadays,fossil fuels are drying up and the global environment is deteriorating.Proton exchange membrane fuel cells are expected to ease the thorny energy crisis in future development as a low-pollution and high-efficiency energy conversion device.The catalyst is one of the important components of the fuel cell.At present,Pt is considered to be the best catalyst for oxygen reduction.In order to reduce the high cost of rare metals,improve the electrochemical activity and durability of catalyst,changing the appearance of the traditional catalyst and leading different transition metals to Pt elements to form alloy catalyst have become a hot spot in the design of oxygen reduction catalyst.In this paper,a series of one-dimensional platinum-based nanostructured oxygen reduction catalysts were prepared by hydrothermal method and hard template method.Then we used SEM,TEM,EDS,XRD,CV,LSV and other characterization methods to test and analyze the composition,morphology,structure and electrochemical performance of the catalysts.The test results were compared with the current commercial platinum black catalysts,the specific content is as follows:First of all,the Pt-Ni nanowire oxygen reduction catalyst was prepared by hydrothermal method without template and external magnetic field.The composition of the catalyst was determined by EDS,and compared with the composition of the added precursor,the controllability of the hydrothermal preparation of platinum nickel nanowires was verified.The existence of nanowire structure was confirmed by TEM and XRD.In addition,it was found that the nanowire structure cannot be synthesized when the Pt content is too low.The results of electrochemical tests showed that the Pt-Ni nanowire oxygen reduction catalyst has a maximum electrochemically active surface area of 58.1 m~2/g,which is superior to the traditional Pt/C catalyst of 46.3 m~2/g.After 1000 cycles of cyclic voltammetry,the decay rate is 34%,which is better than 56%of Pt/C catalyst.In order to further verify the advantages of one-dimensional nanostructure and improve the electrochemical performance and durability of the catalyst,in the second part of the experiment,the hard template method was selected as the preparation method of the catalyst,and the Pd element with high matching degree with Pt crystal form was added to obtain the platinum palladium nanowire oxygen reduction catalyst.Firstly,an ordered porous alumina membrane was synthesized as a template for the catalyst.A platinum-palladium nanowire oxygen reduction catalyst was obtained in the AAO template by electrodeposition.SEM,XRD,and EDS tests showed that the catalyst grew well and was arranged in an orderly manner.The catalyst components and the feed ratio were basically consistent.Through the electrochemical test of the surface activity and durability of the nanowire catalyst,it was found that the maximum ESA can reach 67.4 m~2/g,and the half wave potential of oxygen reduction is shifted about 24 m V compared with the platinum black catalyst.After 1000cycles of cyclic voltammetry scanning,the ESA can retain 58%.The durability is slightly lower than that of Pt-Ni nanowire catalyst,but the electrochemical performance has been greatly improved.