Design of Pd-Based Bimetallic Catalysts for ORR: A DFT Calculation Study

Developing pd-lean catalysts for oxygen reduction reaction (orr) is the key for large-scale application of proton exchange membrane fuel cells (pemfcs). in the present paper,we have proposed a multiple-descriptor strategy for designing efficient and durable orr pd-based alloy catalysts. we demonstrated that an ideal pd-based bimetallic alloy catalyst for orr should possess simultaneously negative alloy formation energy,negative surface segregation energy of pd,and a lower oxygen binding ability than pure pt. by performing detailed dft calculations on the thermodynamics,surface chemistry and electronic properties of pd-m alloys,pd-v,pd-fe,pd-zn,pd-nb,and pd-ta,are identified theoretically to have stable pd segregated surface and improved orr activity. factors affecting these properties are analyzed. the alloy formation energy of pd with transition metals m can be mainly determined by their electron interaction. this may be the origin of the negative alloy formation energy for pd-m alloys. the surface segregation energy of pd is primarily determined by the surface energy and the atomic radius of m. the metals m which have smaller atomic radius and higher surface energy would tend to favor the surface segregation of pd in corresponding pd-m alloys. © 2015 lihui ou.