Ultrathin Carbon Ribbons Conduct Like Metal in First Successful Synthesis

Researchers in China have synthesized an ultrathin carbon ribbon that conducts electricity like a metal, a structure physicists predicted nearly 30 years ago but had never managed to build.

The problem they are chasing is practical. As electronic devices shrink, so do the metal wires inside them, and the smaller the wires get, the more heat they generate and the more their electrical resistance spikes. That hurts performance. Carbon wires are touted as a possible replacement because some types could carry huge currents without degrading while taking up a fraction of the space.

One candidate is a new class of ultrathin conductors called carbon pentaheptite nanoribbons, made by a team at the University of Science and Technology of China and reported in the journal Nature. A Research Briefing in the same issue highlights the promise of these nontraditional carbon structures.

The team wanted ribbons made entirely of five- and seven-membered carbon rings. That is hard because some of the building blocks are unstable and too reactive to handle directly. The workaround was to start from a stable molecule containing an eight-carbon ring and deposit it on a silver surface. Heating caused each eight-carbon ring to rearrange into two fused five-carbon rings. Heating the chains again made neighboring rows zip together sideways, forming seven-carbon rings between them and completing the ribbon.

Physicists had predicted in 1996 that a material made entirely of five- and seven-carbon rings could behave like a metal, but no one had produced these precise carbon structures until now. The next test was whether electrons could pass through them.

Using the sharp tip of a scanning tunneling microscope, the researchers lifted one end of a ribbon off the surface and ran an electrical current directly through it. One version behaved as a true metal, with smooth flow and very high conductance. The other acted as a semiconductor, restricting electron flow at lower voltages. 'CPHN 1 is an intrinsic metal, whereas CPHN 2 is a narrow-bandgap semiconductor,' the authors wrote.

The authors are cautious about what comes next. They describe the metallic ribbon as a promising planar carbon metal and say it suggests 'a possible route toward carbon quantum wires, although further synthetic optimization will be required for device integration.'

The paper, 'Narrow carbon pentaheptite nanoribbon as a covalent metal' by Jianmin Huang and colleagues, appears in Nature (DOI 10.1038/s41586-026-11202-2). The ribbons were made on a silver surface and tested one at a time, so turning the result into usable wiring is a separate engineering challenge.