| dc.description.abstract | Recently, fuel cell technologies have received much attention as an alternative energy source. Fuel cells are like batteries that convert chemical energy into electricity. Different specifications and system design of the fuel cells are required for different applications. Among all the fuel cells, PEM fuel cell produces the most power for a given volume of the
fuel cell, which makes them suitable for vehicles. In this study, pulsed laser deposition (PLD) in Ar atmosphere was used to deposit Pt nanoparticles on the gas diffusion layers (GDLs). There were two methods of tailoring the GLDs have been explored in this study.
The first method is to improve the proton transport by drop casting Nafion on the GDL. The second topic is centered on increasing the surface area of the catalyst by laser micro-machining the GDL.
On the first method, the influence of Nafion® ionomer content drop casted on the GDL was investigated. The addition of Nafion® ionomer content in the catalyst ink enhances the proton conduction. In our study, Nafion® ionomer content is separately deposited on the GDL. The Pt was first deposited on the GDL and afterwards drop casted by Nafion® solution. Different Nafion® concentrations were diluted in different concentrations of water and ethanol. Results showed that the wettability of the substrate and the solution play a great role in achieving the highest current density. At lower Pt loading, 100 μg cm2, the optimized Nafion®, water, and ethanol concentration were 0.05 wt%, 33.5%, and 66.5%,
respectively. On the other hand, at higher Pt loading, 200 μg cm2, the optimized Nafion® concentration was 0.025 wt%. Further characterizations are needed to quantify the drop casting method.
The second method include laser micro-machining the substrate. Laser-micromachining the substrate demonstrate that by increasing the Pt loading the power density does not drop. Increasing the Pt loading increases the film thickness which affects the fuel cell performance. Firstly, the picosecond laser fabricates grooves on the surface of the gas diffusion layer to greatly increase the effective surface area of Pt deposition, thereby re-
ducing the Pt film thickness. And, secondly, pulsed laser deposition was used to deposit the Pt on to the catalyst. A 2-fold increase in the maximum power density is achieved by using laser micro-machined periodic grooves of 40 μm period, 20 μm groove width, and 10 μm depth, reach 853 mW/cm2 and a maxmimum power density of 1.2 mW/cm−2 with a cathode Pt loading of 200 μg/cm2 . Further promotion is expected if the groove width and the period could be reduced by improving the laser micro-machining process. | en_US |