In situ XAFS analysis of cobalt-containing fuel cell cathode electrocatalysts

Oftentimes measuring relevant properties for catalysts must be done in situ. The obvious properties are catalytic activity and selectivity. However, improving catalyst production or discovery may depend on a better understanding of the fundamental structure of the materials under real operating conditions. X-ray absorption fine-structure (XAFS) spectroscopy can be used to probe the atomic and electronic structure of the active electrocatalyst in an operating fuel cell. Specially adapted fuel cell hardware can be used effectively to measure XAFS in situ for transition metal K edges. We present a study of cobalt-containing, non-platinum electrocatalysts that demonstrates the existence of several chemical species under different conditions during the operation of a fuel cell.