| Today,the world is facing a serious energy crisis.On the one hand,the use of fossil fuels has caused serious environmental pollution,on the other hand,the reserves of fossil fuels have continued to decrease.The discovery and use of hydrogen energy can help solve the energy crisis.The proton exchange membrane fuel cell(PEMFC)is used as energy conversion equipment due to their efficient use of hydrogen energy,which can convert renewable hydrogen energy into electrical energy.PEMFC has received extensive attention and research from researchers.In PEMFC equipment,Pt catalysts are often used as cathode catalysts.However,the oxygen reduction reaction(ORR)activity and durability of Pt catalysts are low,and their cost is expensive.These shortcomings limit the performance of PEMFC.Therefore,the development of efficient and durable ORR electrocatalysts is the key to increasing the large-scale commercialization of PEMFC.Related studies have found that PtM(M is a transition metal)alloy catalysts can effectively improve ORR activity,but it is inevitable that the dissolution of transition metals in harsh acidic environments will cause the performance of PEMFC to decline.Ordering the structure of the catalyst and doping the third element in the catalyst can effectively improve the activity and stability of the catalyst.Based on the above background,a variety of Pt-based trimetallic catalysts are designed to improve the ORR performance and stability of the catalyst in this paper.The main research contents are as follows:1.Ordered PtCuNi/C nanoparticles(NPs)were prepared by immersion reduction method.The optimal conditions for generating PtCuNi/C ordered structure were explored by adjusting the annealing temperature and the metal ratio.The electronic structure of Pt can be effectively adjusted by doping Ni in ordered PtCu/C,thereby optimizing the oxygen binding energy of ORR.The relationship between catalyst structure and catalytic activity was explored by electrochemical tests.The results show that the ORR activity of the ordered PtCuNi/C catalyst is superior to that of the disordered PtCuNi/C catalyst.Compared with ordered PtCu/C catalyst and JM Pt/C,the ORR activity and durability of the ordered structure PtCuNi/C catalyst are significantly improved.The outstanding activity and durability are attributed to the synergy and ligand effect between Pt,Cu,and Ni.Specifically,the mass activity of PtCu0.5Ni0.5/C-700 at 0.9 V vs.RHE(reversible hydrogen electrode)is 1.29 A mg-1Pt,which is 9.2 times that of commercial Pt/C.In a single cell system,PtCu0.5Ni0.5/C-700 as a catalyst can exhibit a power density of 461 mW cm-2.This research provides a new design strategy for the preparation of fuel cell catalysts with good electrocatalytic activity and durability,and lays the foundation for the development of subsequent three-way ordered catalyst systems.2.Mo-doped PtCu catalyst(Mo-PtCu/C)with octahedral morphology was prepared using a hydrothermal reaction through a two-step method.different ratios of Mox-PtCu(x=0.01,0.02,0.03)catalysts were prepared by adjusting the amount of Mo.The rotating disc test showed that the activity of Mo-PtCu/C was significantly improved compared with the octahedral PtCu/C catalyst and JM Pt/C.The enhanced activity can be explained by the ligand effect and Mo doping effect.Among them,Mo0.02-PtCu/C greatly improves the ORR rate,and the catalyst mass activity reaches 1.61 A mg-1Pt,which is 11.5 times that of commercial Pt/C.The half-wave potential of Mo0.02-PtCu/C only shifted by 6 mV in the negative direction after durability testing,showing excellent durability.The reason is that a small amount of Mo incorporated into the surface of PtCu nanoparticles can effectively prevent the dissolution of Pt atoms and Cu atom nanoparticles,thereby improving the durability of the Mo-PtCu/C catalyst.3.The ordered O-PtCu/C catalyst is prepared by the impregnation method.Au controlled the surface of O-PtCu/C catalyst to prepare Au-O-PtCu/C catalyst.The crystal form of O-PtCu/C is not affected by the doping of Au.RDE test shows that the catalytic activity of Au-O-PtCu/C is higher than that of O-PtCu/C catalyst,and the mass activity reaches 0.83 A mg-1 Pt,which is 5.92 times higher than that of JM Pt/C. |
