Coaxial cable consists of an inner conducting wire, coated by a non-conducting dielectric, which is in turn coated by another conducting layer. This type of wire has never before been replicated on the nanoscale. Rice Unversity researchers have done just that, by almost complete accident. The team was "just curious to see what would happen electrically and mechanically if we took small copper wires known as interconnects and covered them with a thin layer of carbon," said paper co-author Jun Lou. What happened is that a small dielectric layer of copper oxide formed between the copper and the carbon. Interestingly, the wire has more than ten times the capacitance (or the ability to store electrical energy) than was classically expected. Though the technology is somewhat far off, the team envisions using arrays of millions these nanowires to store energy more efficiently than current batteries.