Platinum-Ruthenium Mixed Metal/Metal Oxides: ReaxFF for Fuel Cell Application

The best currently used direct methanol fuel cell is the Pt-Ru alloy on a proton exchange membrane. In hydrogen fuel cell Ru also improves the CO tolerance of Pt significantly. However, there are still controversies on the nature of the promotion mechanism: a potential-dependent XPS confirmed the presence of Ru oxide species [RuO2 and RuO3] in the PtRu(1:1) electrode at potentials relevant to fuel cell anode catalysts (where Pt remains metallic) and proposed that Ru acts as oxygen transfer promoting agent; another XPS study, however, suggested that the presence of a metallic Ru is a prerequisite for active catalysts and RuOx species act as a catalytic de-enhancer rather than as a promoter.
Little is known also about the optimal Pt-Ru surface concentration, Pt-Ru distribution and surface structure of active Pt-Ru electrocatalysts. Here we develop a reactive force field (ReaxFF) for Pt/Ru alloys and their oxides for a possible use in generating plausible surface structures of Pt-Ru electrocatalysts in working conditions, which will be used in further quantum mechanics calculations on reaction mechanisms.

Personnel: Dr. Yun-Hee Jang

This project is in collaboration with Dr. Adri van Duin and sponsored by General Motors