Optimal Pt-Au Alloying for Efficient and Stable Oxygen Reduction Reaction Catalysts.

Stabilization of cathode catalysts in hydrogen-fueled proton-exchange membrane fuel cells (PEMFCs) is paramount to their widespread commercialization. Targeting that aim, Pt-Au alloy catalysts with various compositions (Pt 95 Au 5 , Pt 90 Au 10 , and Pt 80 Au 20 ) prepared by magnetron sputtering were investigated. The promising stability improvement of the Pt-Au catalyst, manifested in suppressed platinum dissolution with increasing Au content, was documented over an extended potential range up to 1.5 V RHE . On the other hand, at elevated concentrations, Au showed a detrimental effect on oxygen reduction reaction activity. A systematic study involving complementary characterization techniques, electrochemistry, and Monte Carlo simulations based on density functional theory data enabled us to gain a comprehensive understanding of the composition-activity-stability relationship to find optimal Pt-Au alloying for maintaining the activity of platinum and improving its resistance to dissolution. According to the results, Pt-Au alloy with 10% gold represent the most promising composition retaining the activity of monometallic Pt while suppressing Pt dissolution by 50% at the upper potential limit of 1.2 V RHE and by 20% at devastating 1.5 V RHE .