Thursday, March 12, 2009

Graphene Hydride

Do take a look at this image. I almost got excited until I realized that no one had actually made this yet. The only improvement over speculations that I made on exactly this type of carbon structure thirty years ago is that they have shown that it is theoretically stable and possibly workable.

Carbon wonderfully lends itself to this type of theoretical construction. It is your atom of choice if you have an active imagination. It is also proving to be magical when we can actually make something like a very small sheet of graphene.

Research is in full swing and I look forward to someone been able to actually fabricate a three dimensional graphene structure just to store hydrogen. Recall that a serious effort went into the development of metal hydrides thirty years ago for the same reason and that they were a lot easier to fabricate.

Obviously a container holding small pellets would sponge huge amounts of hydrogen into the structure eliminating gas pressure, or at least managing it. This promises to be a light weight method of storing a large amount of hydrogen and well worth the effort.

Designing novel carbon nanostructures for hydrogen storage

George Dimitrakakis, George Froudakis, and Emmanuel Tylianakis

Pillared graphene provides a stable architecture for enhanced fuel storage.

9 March 2009, SPIE Newsroom. DOI: 10.1117/2.1200902.1451

Energy consumption has reached record levels, and global demand is expected to grow by more than half over the next quarter of a century. The greenhouse effect and global warming are only two of the issues we face. In addition, fossil fuel reserves are gradually being depleted. To address these problems, we need a new, clean energy source. Hydrogen is an ideal environmentally friendly energy carrier, since the only product from its combustion is water. The main drawback limiting its wide use is the lack of an efficient storage device.

The United States Department of Energy (DOE) has established targets
1 to be met by 2010 in order to use hydrogen as a fuel for mobile applications. Nanoporous carbon materials, like carbon nanotubes (CNTs),2 were initially considered ideal candidates for hydrogen storage.3–5 However, later work showed that pristine CNTs cannot store sufficient amounts of hydrogen under ambient conditions.6–8 On the other hand, doping CNTs with lithium atoms can considerably increase their capacity.9–11 Efficient storage also requires a material with high surface area and suitable pores.12,13 To fulfill these requirements, we designed pillared graphene.14
As shown in Figure 1, pillared graphene14 is the combination of two allotropes of carbon, CNTs and graphene sheets. The entire structure looks like a building in the early stages of construction, with CNTs forming the pillars and graphene sheets forming the floors. The combined 3D material has tunable pores, in which the length, width, and intertube distance of the CNTs can be changed at will. Tunable porosity is crucial for efficient hydrogen storage.

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