Atomistic understanding of Pt-based medium entropy alloys for oxygen reduction electrocatalysis based on first principles

Abstract

Platinum (Pt)-based multicomponent alloys have been widely regarded as the best catalysts for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). Herein, a set of Pt-based medium entropy alloys with precisely controllable composition and structure have been designed theoretically. The obtained medium entropy alloys like PtCuSn or PtCuW tend to form an atomistic thick Pt-skin structure with W or Sn atomic segregation at the subsurface. Based on oxygen reduction kinetic current calculations, the PtCuSn exhibits an onset potential of 1.09 V and half-wave potential of 0.86 V and also displays increased vacancy energy, revealing remarkably enhanced intrinsic activity and structural stability, compared with the other tested Pt-based catalysts. The improved ORR activity can be attributed to unique electronic structure, compressive microgeometry, and low work function. This work can shed a light on the design of novel medium-, high-entropy nanoalloys as next-generation catalysts for PEMFCs.