Optimal ionomer interaction resolved by operando X-ray Absorption Spectroscopy and gas sorption analysis

To bridge the gap between oxygen reduction electrocatalysts development and their implementation in real proton exchange membrane fuel cell electrodes, an important aspect to be understood is the interaction between the carbon support, the active sites, and the proton conductive ionomer as it greatly affects the local transportations to the catalyst surface. To gain a deeper understanding of the catalyst-ionomer interaction, three Pt/C catalysts were prepared with the same polyol method using three different carbon support: low surface area Vulcan carbon, high surface area Ketjenblack carbon and in-house developed ordered mesoporous carbon. The Pt/C catalysts supported on ordered mesoporous carbon derived from biomass showed the best performance under the gas diffusion electrode configuration. Through a unique approach of operando X-ray Absorption Spectroscopy (XAS) combined with gas sorption analysis, we were able to demonstrate the beneficial effect of mesopore presence for optimal ionomer-catalyst interaction at both molecular and structural level.