doi:10.3850/978-981-07-0319-6_213

ABSTRACT

In this study two different approaches to make thin multifunctional membranes of carbon nanotubes will be compared. The membranes can be used to form a catalytic layer in a proton exchange membrane fuel cell. The most straight forward method is to directly depose drops of previously dispensed nanotubes on a Si-substrate. For easy release of the membrane the substrate is coated with an additional hydrophilic sacrificial layer, in this case a sputter deposited thin Al-film. The advantages of this method are the easy handling of the process and short fabrication times. But, there is a high probability of pin-hole generation within the membrane if it undergoes a thickness of approximately 6 µm. In contrast, the layer-by-layer deposition technique follows a bottom-up approach, making subsequently bilayers of functionalized nanotubes attached by electrostatic forces. This method provides the possibility to control the layer thickness very precisely and to achieve a minimal defect density. Like every step-by-step method, the processing time depends on the final thickness which can be disadvantageous when targeting thicker membranes.

Keywords: Fuel cell, Carbon nanotubes, Layer-by-layer.

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