Design Strategies for High Performance of Proton Exchange Fuel Cells with Ti‐Sputtered Carbon Nanotube Sheet Functional Layer

Abstract Optimizing both performance and stability under varying relative humidity (RH) conditions is crucial for proton exchange membrane fuel cells (PEMFCs). Therefore, effective management of mass transfer and water is an essential key factor. To further improve performance and stability, this paper reports a novel PEMFC design strategy that introduces carbon nanotube (CNT) sheets with titanium (Ti) deposited onto them as an additional functional layer using the sputtering method. The Ti‐CNT (as Ti‐deposited CNT is abbreviated to Ti‐CNT) sheets are inserted between the catalyst layer (CL) and the gas diffusion layer (GDL). This exhibit enhances performance across all testing conditions (25‐100% RH), which is attributed to their optimal pore structure and hydrophilic properties. It shows up to ≈94% higher power density and ≈60% improvement in charge transfer resistance compared to conventional. Moreover, stability tests conducted under a constant voltage demonstrated that this innovative design strategy significantly reduced degradation, thereby proving its superior stability. This novel design strategy of inserting Ti‐CNTs as a functional layer improves electrochemical performance and stability.