Preparation Of PtPdCu Trimetallic Alloy Catalysts For Electrocatalytic Oxidation Of Ethanol

Direct ethanol fuel cells(DEFCs)are promising energy supplies owing to the unique advantages of ethanol,i.e.,high energy density,low toxicity,easy storage and transportation.At present,ethanol electrooxidation reaction(EOR)faces the great challenges of sluggish reaction kinetics,intricate catalytic pathway,resulting in the low energy conversion rate of ethanol.Therefore,the commercial use of DEFCs is largely limited by its low current output.Alloying strategy can modify the geometric and electronic structures of Pt metal,effectively improve the catalytic activity and alleviate the CO poisoning of the catalysts.Compared with Pt-based binary alloy catalysts,ternary nanoalloys provide more possibilities and flexibility for regulating electronic structure.In this thesis,PtPdCu nanoalloy catalysts were prepared via solvothermal method and their catalytic performance towards EOR was investigated.The detailed research contents are as follows:(1)Preparation of PtPdCu concave cubes with different Cu contents for EOR.By controlling the additive amount of Cu²⁺ions,the composition and morphology of PtPdCu nanoalloy were systemically tailored.By increasing the amount of Cu²⁺ions,the surface depression increased,forming sharp edges.When the amount of Cu²⁺ions was further increased,quasi-cubic structure assembled with 20 nm nanocubes was obtained.In particular,the as-prepared Pt_52.6Pd₄₇Cu_0.4 concave cubes displayed a core-shell structure by showing Pd core and Pt Cu shell.Among all the PtPdCu alloys,the Pt_52.6Pd₄₇Cu_0.4 concave cubes with the lowest Cu²⁺content exhibited the best catalytic activity towards EOR by showing a mass activity of 68.7 m A mg^-1_{Pt Pd} and specific activity of 3.2 m A cm^-2.(2)Preparation of PtPdCu nanodendrites for EOR.By changing the additive amount of KI,PtPdCu nanodendritic(PtPdCu NDs)catalysts with abundant surface defects were synthesized.The obtained PtPdCu NDs exhibited mass activity of 5.59 A mg^-1_{Pt Pd},and the specific activity of 15.82 m A cm^-2,which was 6.4 and 3.6 times than those of commercial Pt/C.Further experiments showed that PtPdCu NDs displayed a strong resistance to CO poisoning.The impressive catalytic activity of PtPdCu NDs towards EOR could be attributed to the large specific active areas,abundant surface defects as active sites,and synergistic effect from Pd and Cu elements,promoting the cleavage of C-C bonds and improving the selectivity of the C₁ catalytic pathway.