Optimized Pt-Based Catalysts for Oxygen Reduction Reaction in Alkaline Solution: A First Principle Study

Abstract

The combined density functional theory (DFT) and kinetic Monte Carlo (KMC) is employed to understand the capability of Pt alloys via Pt-X-Pt sandwich motif in tuning the oxygen reduction reaction activity and stability of Pt catalysts in alkaline solution. For X = Fe, Co, Ni, Cu, the structure of Pt-X-Pt alloy is likely to stay under reaction condition for lowering the surface energy. Both Co and Ni are identified as promoters, being able to facilitate the removal of hydroxyl from the surface and the ORR; while all four systems show the enhancement in the stability of surface Pt compared to pure Pt. For X = Ti, Mn, Ce, the alloyed X metal is too active, which tends to anti-segregates to the Pt surface and forms oxides due to the strong X-O interaction. Wherein, the decoration of Ce oxide shows a promoting effect for the ORR on Pt, which induces strain on the neighboring Pt-Pt bonds and helps in release of hydroxyl species; yet it destabilizes the interacted Pt atom and can lead to the deactivation of the catalyst.