Effect Of Morphology And Composition On The Oxygen Reduction Performance Of Platinum Group Nano-Electrocatalysts

Among noble metals(Pt,Pd,Au,etc.)based nanomaterials,Pt-based nanomaterials have high catalytic activity in both cathode and anode reactions,which are considered to commonest catalyst for fuel cells.Adjusting morphology and composition by simple methods for electrocatalysis are the research focus.To this end,dissertation aims to design dendritic,tripod,mesoporous cage-bell,and mesoporous nanotube noble metal catalysts to improve the performance for electrochemical applications and obtain catalysts with lower cost,higher catalytic performance and better stability.This dissertation focuses on the modification of catalyst morphology to improve the electrocatalytic performance:Firstly,a very simple one-step method is used to synthesize PtPdCu tripods(PtPdCu TPs)nanocatalyst with high yield in aqueous solution.Different from the multi-step synthesis route in oil phase,the method is very simple.Different from the reported tripods structure with smooth surface,each branch of PtPdCu TPs has graded branches,which can effectively increase the specific surface area and expose more electrochemically active sites,thus effectively improving the performance in oxygen reduction reaction.Secondly,a one-step method is designed to synthesize a trimetallic PdCuAu(PdCuAu NAs)catalyst with three-dimensional nanothorn in aqueous solution.This unique PdCuAu NAs is a self-supporting nano-structure formed by self-assembly of stacked nanothorn.PdCuAu NAs exhibit higher catalytic activity,stability and methanol tolerance in oxygen reduction reaction than commercial Pt/C due to their branching structure and trimetallic properties.Thirdly,a method is designed to synthesize mesoporous Pt cage-ball nanostructures(Pt@mPt CBNs).The novel structure consists of an outer mesoporous Pt shell and an inner Pt nucleus.The outer mesoporous Pt can not only effectively increase the active sites,make full use of the inner surface of the shell,but also facilitate the transport of the electrolyte to the catalyst and catalyze the reaction with the inner core.In addition,the existence of outer shell can prevent internal nuclear agglomeration,increase the stability of materials,and extend the service life.This structural feature enables Pt@mPt CBNs to exhibit outstanding performance in electrochemical applications.Finally,the design of one-dimensional nanostructures with continuous mesopores is of great significance for electrocatalytic applications.A flexible wet chemical method is developed to synthesize Pt?Te mesoporous nanotubes(Pt?Te MNTs).In the synthesis process,the double-template method is used,and the reductive ultra-long Te nanowires are used as sacrifice templates to guide the formation of one-dimensional nanotubes.As a pore-forming agent,the surfactant F127 can guide the formation of mesopores.The characteristics of mesoporous tubular make Pt?Te MNTs show prominent advantages in catalytic oxygen reduction reaction.