Local Composition of Alloy Catalysts for Oxygen Reduction by STEM-EDS

Fuel cell technology is a potentially clean alternative to traditional power sources, in particular for the automotive industry [1]. The widespread usability is limited by the high cost of the Pt cathode catalyst [2]. Numerous studies therefore focus on finding cheaper alternative catalysts with higher efficiency for the oxygen reduction reaction (ORR) [3]. Bimetallic catalysts are known for their enhanced ORR activity [3,4]. Pt3Y has been identified based on density functional theory calculations as being both active and stable for ORR. Recent experimental results have shown that PtxY in nanoparticulate form exhibit an unprecedented ORR activity of 3.05 A/mg at 0.9 V with respect to a reversible hydrogen electrode [5,6]. Following the same scheme but focusing on the electrochemical oxygen reduction for the production of hydrogen peroxide, Pd-Hg nanoparticles have been identified as a metal electrocatalyst exhibiting high mass activity [7,8]. In order to understand the enhanced performance of these catalysts, knowledge of how the two elements forming the bimetallic compound are distributed at the atomic level is important.