Interfacial structure of adsorbed short-side-chain perfluorosulfonic acid ionomer on carbon surfaces in N-propanol/water mixtures

Overview & Synopsis

The adsorption of perfluorosulfonic acid (PFSA) ionomers on carbon surfaces is a key process governing the formation of catalyst layers in electrochemical energy devices, yet the influence of solvent composition on interfacial structure remains poorly understood. Here, quartz crystal microbalance with dissipation monitoring (QCM-D) is used to investigate the adsorption of a short-side-chain PFSA ionomer on model carbon surfaces in N-propanol / water mixtures. Adsorption kinetics, equilibrium behavior and viscoelastic properties of the interfacial layer are analyzed as a function of solvent composition, ionomer concentration and thermal history. The results show that solvent composition strongly affects both adsorbed mass and layer mechanics, with alcohol-rich mixtures promoting more rigid and cohesive films. In addition, atypical adsorption behavior is observed at low ionomer concentrations in specific conditions, indicating competing effects of solvation, restructuring and interfacial coupling. These findings provide molecular-level insight into PFSA-carbon interactions in mixed solvent environments.