Modeling, Design and Fabrication of Non-Uniform Catalyst Layers for PEM Fuel Cells

Catalyst layers are one of the most important parts of the PEM fuel cells and the cell performance is highly related to its structure. Catalyst layers are generally made by uniform distribution of catalyst on carbon cloth or carbon papers to form electrodes. In this paper, the idea of using non-uniform catalyst layer instead of common uniform catalyst layers is presented and simulated by a two-dimensional steady-state computational model. The model accounts for species transport, electrochemical kinetics, charge transport and current density distribution. A fuel cell test stand is designed and built to facilitate experimental validation of the model. Modeling results show that electrical current in catalyst layer is non-uniform, influenced by the channel-land patterns in bipolar plate geometry. Our simulations results also suggest that some non-uniform catalyst distribution patterns regarding to bipolar plate configuration will improve the performance of the whole catalyst layer by increasing catalyst utilization factor. Therefore, it is necessary to design non-uniform catalyst layers regarding to specific procedure. Plasma sputtering method is used to fabricate non-uniform catalyst layers. In this method, the platinum is deposited on the carbon cloth in the plasma-processing chamber. Indeed, an experimental procedure is presented to facilitate the fabrication of non-uniform catalyst layers by plasma sputtering.