| An air electrode is widely used in fuel-cell,metal-air cell and other electrochemical industries,for example,electrolysis industry. It plays a critical role in those fields. The catalyst for oxygen reduction in an air electrode is of great importance for development of batteries and electrolysis industry. It has been found that life and activity of catalyst Pt-Fe/C are improved greatly,with the addition of Fe to catalyst Pt/C.In this thesis,the reasons of such an improvement have been studied using ab initio and density function theory (DFT).There are three cluster models used for calculation. They are composed of carbon carrier and Pt(100),Pt(llO),Pt(111) respectively,i.e.,Pt(100)/C,Pt(110)/C and Pt(111)/C. It has been found that not only the metal particles and carbon carrier combined more closely,but also the charge density of atom Pt in Pt(100) and Pt(111) and the Fermi level of all three cluster models are increased in catalyst Pt-Fe/C compared with catalyst Pt/C. It has also been studied that the influence of the cementite formation in catalyst Pt-Fe/C,as it is heated. In the end,the adsorptive oxygen on catalyst (electrode) surface has been evaluated. The results have shown that the O-O bond in catalyst Pt-Fe/C is weaker than that in catalyst Pt/C. It discloses why the catalyst Pt-Fe/C displays a better catalysis than the catalyst Pt/C. |
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