Study On Structure-function Relationship Of AuCu_x/C For ORR And Conception Design Of Ordered AuCu/C Preparation Process

Recently,it has been continuously found that the structure of alloy catalyst has an important effect on the its activity for ORR.There are many structures have been researched which consists of core-shell structure,hollow structure,porous structure and ordered structure.However,whether ordered structure is beneficial for ORR is still at issue.This is mainly because that the ordered structure is obtained by high temperature annealing,while the disordered structure is acquired by relatively lower temperature.The large temperature gap can't remove the increase of the particle size.Thus,it is impossible to eliminate the effect of size when we compare their different electrochemical performance.In this paper,we successfully synthesized AuCux/C electrocatalysts through a modified co-precipitation method and obtained their ordered and disordered structure at different temperatures.The annealing temperatures are close for the ordered and disordered samples,which eliminates the effect of size increasing on annealing due to significant rise of temperature.Then the electrochemical performance of as-synthesized catalysts are tested.Physical characterization is also used to reveal the difference between the ordered and disordered nanoparticles.Besides,conception design of ordered AuCu/C preparation process is carried out.The results are as follows:The appearance of the superlattice peak prove that the ordered structure has been obtained.The distribution of the particle size counted from the TEM pictures,shows the similar average size between the ordered and disordered structure.The measurement of the supperlattice space from the HR-TEM pictures also supports the formation of the ordered nanoparticles.The EDS mapping results show that it tends to form a Cu-shell structure on the surface of the disordered structure.The XPS analysis shows that there is no distinct difference in the composition and value state between the ordered and disordered structure.The measurement of the LSV curves and the calculation of the half-wave potential demonstrate that the ordered structure is more beneficial for ORR than the disordered one.The K-L curves and Tafel curves are also used to reveal the different electrochemical performance of the ordered and disordered nanoparticles.Then the DFT calculation and the calculation of the d-band density of states of different surfaces of the ordered and disordered structure show the mechanism of their different electrochemical behavior.In addition,the ordered AuCu and the ordered porous AuCu are used as the core,then a Pt monolayer deposits on their surfaces.Their different electrochemical performance for ORR is tested under acidic and alkaline conditions.The result shows that both of the two core-shell materials have excellent ORR performance in acidic and alkaline conditions.The emergence of porous structure will not significantly low its ORR performance,so it can reduce its cost by replace the AuCu by porous AuCu.Finally,based on the market research,the conceptual design of AuCu/C catalyst with the highest ORR activity is carried out.The results show that the process is not only feasible but also has high economic efficiency.