Preparation Of Low-platinum Catalysts For Fuel Cells And Study On Oxygen Reduction Properties

As an environmentally friendly and efficient new energy conversion technology,fuel cells are currently a hot research topic.Precious metal catalysts exhibit the advantages of high catalytic activity and stability and are the most promising catalysts for fuel cell oxygen reduction reactions.Among them,Pt-based catalysts have now become the focus of research.From a long-term perspective,the cost of precious metals is too high for long-term development,and in order for them to achieve this goal,the development of low-Pt catalysts becomes particularly important.Research in recent years has shown that platinum alloy catalysts is a promising material for research.In this thesis,a series of low-platinum catalysts were prepared from platinum acetylacetonate,nickel acetylacetonate and yttrium acetylacetonate hydrate as the main raw materials.The catalyst activity,stability,and the pattern of the catalyst were investigated by various characterization methods to study the structural morphology and performance of the catalyst.The main research results are as follows:1.The octahedral Pt Ni alloy was synthesized by hydrothermal method from platinum acetylacetonate and nickel acetylacetonate.Then Pt Ni/C catalysts were synthesized with carbon-loaded Pt Ni alloy.It was found that the best ORR catalytic performance of octahedral Pt Ni/C-84（Pt loading of 10.05%）was achieved when the ratio of platinum acetylacetonate to nickel acetylacetonate was 8:4.In acidic media,its half-wave potential reached 0.898 V.At 0.9 V,the mass activity and specific activity reached 0.099 Amg_pt^-1 and 0.62 m Acm^-2,respectively,which were 2.7 and 10.3 times of commercial 40%Pt/C.The successful performance was mainly due to the high oxygen reduction activity of Pt（111）exposed to the octahedral profile.2.A series of Pt Y/C alloys（Pt loading of 6.4%）were hydrothermally synthesized by dissolving platinum acetylacetonate,yttrium acetylacetonate hydrate,and carbon powder in N,N dimethylformamide（solvent/reducing agent）.It was shown that the best performance was achieved when the hydrothermal temperature was 150°C,and the half-wave potential of Pt Y/C-150 reached 0.868 V,which was almost comparable to that of commercial 40%Pt/C（0.868 V）.At 0.9 V,the mass activity and specific activity of Pt Y/C-150 reached 0.13Amg_pt^-1 and 0.43 m Acm^-2,respectively,which were 3.5 and 7.17 times of those of commercial 40%Pt/C,indicating that the catalyst has a good oxygen reduction response.3.Ternary low-Pt Pt Ni Y/C alloys were synthesized using platinum acetylacetonate,yttrium acetylacetonate hydrate,and nickel acetylacetonate as precursors.It was found that the introduction of a certain ratio of Ni and Y elements by a two-step method significantly improved the utilization of Pt.This led to the advantageous growth and full exposure of Pt（111）and the synthesis of a ternary low-Pt alloy（11.55%Pt loading）with high performance and high stability characteristics.At 0.9 V,the mass activity and specific activities are 0.15 Amg_pt^-1 and 0.16 m Acm^-2,respectively,which are 4.05 and 2.67 times higher than that of commercial 40%Pt/C.The half-wave potential was as high as 0.948 V,exhibiting excellent catalytic performance.The accelerated durability test results showed that the prepared Pt Ni Y/C-160 catalyst was more stable than the commercial 40%Pt/C.