Performance Of Several New Catalysts For Fuel Cell Cathode

Due to the advantages of low temperature operation,high power density and free of pollution,proton exchange membrane fuel cell（PEMFC）is an ideal device for the future energy utilization.However,the widely used Pt/C acted as the cathodic catalyst hinders its further commercialization.In the regard,the development of low-cost and high-performance Pt-based or even non-Pt catalysts raises great attention.Focused on some catalysts with low Pt content,the corresponding activities were systematically investigated based on the thermodunamic analyais by the first principle calculation.The main contents of our thesis include the following aspects.Firstly,the effects of the interlayer ZrC,HfC,TiN and the thickness of the Pt shell on the adsorption ability and the catalytic activity of the TiC@Pt core@shell structures are systemically investigated.Firstly,the presence of TiN significantly enhanced the adsorption ability of the Pt shell,leading to the deterioration of the ORR activity whilst the negligible influence of the ZrC and HfC insertion results the comparable performance with respect to TiC@Pt.In addition,increasing Pt shell thickness can reduce the adsorption energies of ORR adsorbate and mitigates the OH poisoning.Herein,multilayer Pt shell could improve the catalytic activity of TiC@Pt with the optimized TiC@Pt_2ML.Sencondly,the catalytic activity of two-dimensional metal-organic framework TM₃（HITP）₂ was systematically studied.ORR activity show a classical volcano curves as a function of OH adsorption energy,where Pt,Ni and Pd show low oxyphilic ability and prefer the 2e^-mechanism but the other TM are located on the strong adsorption side along with the poisoning.Based on the overpotential data,ORR activity was decreased in the order of Ir>Co Rh>Ni Pd>Pt Fe>Ru>Os.The central atoms of Co,Rh and Ir possess good catalytic activity and 4e^-selectivity.In the last part,the effect of metal central atoms and its coordinated N ligand on the activity of graphene are systemically investigated.Firstly,for the 3d transition metal elements（Sc;Ti;Vi;Cr;Mn;Fe;Co;Ni;Cu;Zn）doped graphene,Sc/G and V/G posses the strongest oxygen affinity while the weakest capture capability is found on the Cu/G and Zn/G.Herein,the presence of TM could significantly improve the catalytic activity of graphene where Ti/G and Cu/G exhibit excellent ORR catalytic activity.In addition,the effect of N ligand was further studied where Fe,Co and Ni were selected as representative.The results showed that the synergistic effect of N ligand and TM active center can boost the ORR catalytic activity.Herein,NiN₁ conbination was confirmed as a potential electricalcatalysts.