graphene

I think in the future much of our electronics might be carbon-based rather than silicon-based. Graphene -- a single layer of carbon atoms in a flat hexagonal sheet -- has a lot of fascinating properties. It turns out that two layers of graphene where one layer is rotated 1.1 degrees with respect to another becomes a superconductor (conducts electricity without resistance). Unfortunately this double layer of graphene has to be cooled to about –271° Celsius to show this effect. It has another interesting trick too: apply an electric field and it turns into an insulator. That is, it can be a switch. (See https://www.sciencenews.org/article/give-double-layer-graphene-twist-and-it-superconducts )

Graphene is also much stronger than steel, is flexible, and can be made at very low energy. At normal temperatures graphene is about 40% better conductor of electricity than copper, yet far lighter. The raw material (carbon) is one of the most common on Earth, and if we made carbon-based things out of thin air, like plants do, building their structures from carbon dioxide, we might help counter greenhouse gas build-up.

The biggest drawback is that we don't yet know how to routinely construct arbitrarily large flawless sheets of it. But you can bet we will solve it.

A prediction from me: I think cables made from long graphene tubes (also called bucky tubes) wound together will be used to make the space elevator, which will bring extremely cheap space travel to everyone.