Fabrication methods for low-Pt-loading electrocatalysts in proton exchange membrane fuel cell systems

While the use of a high level of platinum (Pt) loading in proton exchange membrane fuel cells (PEMFCs) can amplify the trade off toward higher performance and longer lifespan for these PEMFCs, the development of PEMFC electrocatalysts with low-Pt-loadings and high-Pt-utilization is critical. Such development strongly depends on the electrode fabrication method and the loaded substrate. This study presents some of the latest research into promising methods of reducing the Pt loading while increasing the Pt utilization of the electrocatalysts used in PEMFCs. The application of the modified thin film method, despite its relatively higher Pt utilization, to micro-PEMFC applications has proven ineffective due to relatively higher Pt loadings. Although electrocatalysts fabricated by the electrodeposition method achieved the highest Pt utilization, the application of this method to large-scale manufacturing is doubtful due to concerns regarding its scalability. The advantage of the sputter method is its ability to deposit Pt directly onto various components of the membrane electrolyte assembly (MEA) with ultra-low-Pt-loadings. However, the low utilization and poor substrate adherence of the Pt remain challenges. Nevertheless, if these technical problems are overcome, this method appears to be the most promising technology for micro-systems and automotive application fields. Other methods, such as dual IBAD method, electro-spray technique and Pt sols methods, exhibited relatively lower Pt loadings and higher Pt utilization. However, these methods require further research to evaluate their capabilities and improve their reproducibility. Instead of the traditional carbon supports for electrocatalysts, nano-carbon supports such as nanotubes, powders, fibers and aerogels could be effectively used to reduce the Pt loadings. (c) 2007 Elsevier B.V. All rights reserved.