Insights into Oxygen Mass Transport Mechanisms in High-Temperature Proton Exchange Membrane Fuel Cells with Microelectrode

The mass transport of oxygen in the cathode catalyst layer of high-temperature proton exchange membrane fuel cells (HT-PEMFCs) has a great impact on cell performance. However, some bulk average methods are unable to study the permeation properties of oxygen near the triple phase boundary of HT-PEMFCs due to the size mismatch. Here, we develop a microelectrode integrated system to quantitatively study the O2 mass transport behavior at the Pt/binder interface under actual operating temperatures (100 degrees C-180 degrees C). The oxygen diffusion coefficients and solubility obtain from potential-step chronoamperometry and a modified Cottrell equation follow the diffusion "ball-cage" model and the dual-mode solubility model. Subsequently, molecular dynamics simulations are used to describe the key structural elements and diffusion behavior of oxygen molecules from the microscopic perspective. These results provide a scientific approach to study the mass transfer process of oxygen at the local environment, endowing with insightful strategies for future improvement and applications of HT-PEMFCs. A high temperature microelectrode system for study of HT-PEMFCs was built.O2 diffusion and permeation properties near the triple phase boundary were characterized.The mechanisms of O2 mass transfer in the local catalyst layer of HT-PEMFCs were revealed.