Dft Study Of Novel Catalysts In Proton Exchange Membrane Fuel Cells

Recently, proton exchange membrane fuel cells (PEMFCs) have become the most potential clean energy devices. For this reason, the study of PEMFCs catalysts has drawn more and more attention. Here, the density functional the-ory (DFT) calculation was used to search for novel electrocatalysts. The work of this paper can be divided into three sections. In the first section, the DFT calculation was used to screen the promising core-shell Pt-alloys which were modified by transition metals. In the second section, DFT calculation was used to explore the potential single atom catalysts which consisted of transition metals and graphene. In the third section, DFT calculation was used to guide the experiment synthesis. The conclusions of this paper are as follows.(1) Based on the experiment study, a set of slab models, like Pt(111), Pt3M(111), Pt(111)-skin, and Pt(111)-subsurface, and cluster models, like Pt13 and Pt12M, were designed to explore the oxygen reduction reaction (ORR) fa-vorable catalysts. The DFT calculation confirmed that the ORR activity of the four slab models nearly followed the order of Pt-subsurface> Pt-skin> pure Pt> Pt3M. Besides, among the Pt-subsurface alloys, the alloys with early tran-sition metals, such as Mn and Fe, were predicted to be the most favorable ORR catalysts. What’s more, for the cluster model, the Pt12 Mn and Pt12Fe clusters were also found to be the optimal ORR catalysts. Therefore, it can be predicted that the core-shell Pt-alloys with Fe or Mn were potential ORR cat-alysts.(2) The single atom catalysts were designed with transition metals and graphene. For the stability, the single atom catalysts including Ti, Fe, Co, Ni, Zr, Ru, and Rh were favorable. Further study found that the single atom cata-lysts may well be the potential ORR catalysts. Through the oxygen atom ad-sorption calculation, we found that Zr/graphene, Y/graphene, Sc/graphene, and Ti/graphene were the favorable ORR catalysts, and the oxygen adsorption calculation confirmed the conclusion. Through the charge analysis, there are more charge transferring into oxygen atom when oxygen atom is adsorbed on early transition metals, which finally facilitates ORR.(3) Through DFT calculation, we also predicted a volcano-shaped rela-tionship between the FAO activity and the Pt-layer thickness on Cu substrate, and Pt1Cu(111) would be the best FAO catalyst. After that, subsequent synthe-sis and electrochemical measurements of Cu@Pt nanowires with various shell thickness were conducted, which showed that the FAO activity of these cata-lysts were in good agreement with the predicted trend.