Investigating the Particle Growth in Bimodal Pt/C Catalysts by In-Situ Small-Angle X-ray Scattering: Challenges in the Evaluation of Stress Test Protocol-Dependent Degradation Mechanisms

The influence of different combinations accelerated stress test (AST) protocols simulating load-cycle and start/stop conditions a proton exchange membrane fuel cell (PEMFC) vehicle is investigated on bimodal Pt/C catalyst. catalyst, prepared by mixing two commercial catalysts, serves as model system consists distinguishable size populations. change in mean particle was situ small-angle X-ray scattering (SAXS). comparison to the reference i.e., single-size population uncovers presence electrochemical Ostwald ripening degradation mechanism Increasing harshness applied AST protocol faster changing between or conditions, larger catalyst increases than expected. Surprisingly, smaller indicates increase for harsher protocols, which might be explained substantial ripening.