| Fuel cells,as the most promising energy conversion devices attracted much attention.To date,the most widely used catalysis for cathode and anode electrocatalytic reaction are Pt and Ir based precious metals due to their exrcellent electrocatalytic properties.However,the high cost of precious catalysts greatly hampered the practical application for fuel cell,by adjusting the morphology of catalyst to control the surface arrangement of atoms is an effective strategy for reducing the amount of precious metals and improve the efficiency of electrocatalysis.Based on this,the study focused on synthesizing PtIrCu ternary alloy catalyst with reducing agents and capping agent to regulate the structure.Its catalytic performance for ammonia oxidation（AOR）,methanol oxidation（MOR）and oxygen reduction（ORR）have studied,and the structure-activity relationship between the structure and the catalyst activity was revealed.The specific research contents are shown as follow:（1）A novel structure of PtIrCu hyperbranched concave octahedral nanodendrites（HCOND）with high-index facets was synthesized by one-step solvothermal method.PtIrCu HCOND has high AOR activity due to its rich in Pt-Ir surface,strain effect,open structure and{553}{331}and{221}high-index facets.The performance of PtIrCu HCOND is also superior to other forms of Pt-based catalysts previously reported（PtIr Ni/Si O2-CNT-COOH nanoparticles,PtIr nanocube,Pt Ni nanoflower,etc.）.In short,this work not only proposed for the first time that ternary PtIrCu can be used as an efficient AOR catalyst in low temperature alkaline media,but also verified for the first time the promotion of AOR with high-index facets.（2）PtIrCu concave octahedral nanoframe（HCONF）is obtained by etching PtIrCu HCOND.PtIrCu HCONF exhibited high efficiency MOR and ORR activity and stability in acidic medium.In anode MOR,the mass activity of the positive scanning peak potential of PtIrCu HCONF is4.2 times that of commercial Pt/C.At the same time,the mass activity of PtIrCu HCONF in cathode ORR is 7.42 times higher than that of Pt/C at0.9V vs RHE.The results show that the nanoframe structure has advantages in acidic medium.（3）In order to further explored the relationship between the structure and the intrinsic properties of AOR.PtIrCu prismatic dodecahedral nanoframes（RDNFs）,PtIrCu hyperbranched hyperbranched multilayered octahedral nanocrystals（HMONCs）and PtIrCu smooth nanoparticles（NPs）were synthesized.The results showed that PtIrCu RDNFs exhibited high AOR activity and strong stability in alkaline medium.The onset potential of PtIrCu RDNFs was 0.38 V vs RHE,and the peak current density（JP）was 241.9 A g-1PGM.In addition,the current density of 19.8 A g PGM-1was maintained after 3 h of CA test,which was better than other reports previously.In conclusion,these results demonstrate that the alloy effect of PtIrCu and the structural advantages of nanodendritic,nanolayered and nanoframes.This will provide new ideas for the design of novel electrocatalysts for ammonia oxidation.Meanwhile,this effective strategy creates better conditions for the effective development of direct ammonia fuel cells. |
