Researchers from Stanford University and the SLAC National Accelerator Laboratory have discovered a new 2D material (which they call Stanene) that may conduct electricity better than graphene. Stanene is actually a topological insulator - and as such its edges conduct electricity with 100 percent efficiency.
Stanene is similar to graphene, but it is made from tin atoms. The researchers say it is the first material to conduct electricity with 100% efficiency at the temperatures that computer chips operate. Of course this is all currently just theoretical predictions, but hopefully soon experiments will confirm those predictions.