Ordered and Ultra-High Aspect Ratio Nanocapillary Arrays as a Model System

Nanocapillary arrays are attractive structures for many applications due to the relative ease and scalability of the self-assembly process of their formation. The high surface area-to-volume ratio of these structures can benefit a wide range of energy technologies such as photovoltaics, electrochemical capacitors and batteries, as well as a range of chemical technologies such as separations, storage and catalyst scaffolding. We are currently demonstrating their utility for high density storage of gases such as hydrogen and oxygen. Their high aspect ratio and ordered arrangement is advantageous for low-cost, bottom-up, templated nanostructure growth and ordered assembly at the device scale. Assembly of nanostructures the device scale in the absence of a templating structure, while maintaining the benefits of a nanomaterial, is often the dominant technical hurdle for implementation of nanomaterials into technologies. In previous work we have used AAO templating to maintain nanostructure benefits for photoelectrochemical cells with areas exceeding several square centimeters. Furthermore, the confined radial dimension of nanocapillaries can be used to synthesize molecularly confined or form quantum confined nanostructures. We have shown these effects benefit to improve double layer capacitance, as well as improving the figure of merit in nanostructured thermoelectrics. Specifically of interest in this discussion is the formation and deep pore growth of anodized aluminum oxide (AAO)-based nanocapillary arrays as the basis for high density, safe and high rate gas storage devices. The target is to grow these ordered nanocapillaries structures to centimeters in length while maintaining a uniform 100 nm nanocapillary diameter and an overall structure that is 100's cm2 in area. Presented at the 228th ECS Meeting, 14 October 2015. CA: Air Force Test Center Edwards AFB CA CC: 012100