In-Situ XANES of Carbon-Supported Pt−Ru Anode Electrocatalyst for Reformate-Air Polymer Electrolyte Fuel Cells

In-situ X-ray absorption near-edge structure (XANES) experiments were performed on a working reformate-air fuel cell to study the structure of carbon supported Pt−Ru anode electro-catalyst. The fuel cell was operated in a normal mode without the use of supplemental electrolytes. A fresh membrane electrode assembly (MEA) and a conditioned MEA were studied at different operating conditions of the fuel cell and different feed (pure H<INF>2</INF> or H<INF>2</INF>/CO [100 ppm CO]) at the anode. The in-situ Pt L<INF>III</INF>-edge and Ru K-edge XANES of the fuel cell MEAs showed metallic characteristics under all operating conditions. These results demonstrate that, under the reducing conditions of normal fuel cell operation, the Pt−Ru catalyst exists as a metallic phase(s).