Optimizing PtFe Intermetallics for Oxygen Reduction Reaction: From DFT Screening to In-Situ XAFS Characterization
Rational designing of catalysts to promote the sluggish kinetics of cathode oxygen reduction reaction in proton exchange membrane fuel cells is still challenging, yet of crucial importance to its commercial application. In this work, on the basis of theoretical DFT calculations which suggest that order structured fct-phased PtFe (O-PtFe) with atomic Pt shell exhibits superior electrocatalytic performance towards ORR, the desired structure was prepared by using a scalable impregnation-reduction method. The as-prepared O-PtFe delivered enhanced activity (0.68 A mg-1Pt) and stability (73% activity retention after 10000 potential cycles) compared with the corresponding disorder PtFe alloy (D-PtFe) and Pt. To evidence the excellent durability, in-situ X-ray absorption fine structure spectroscopy was conducted to probe the local and electronic structures change of the O-PtFe during 10,000 cycles accelerated durability testing. We hope this facile synthesis method and the in-situ XAFS experiment could be readily adopted to other catalyst system, facilitating the screening of highly efficient ORR catalyst for fuel cell application.