Chinese team solves 30-year atomic material problem, selectively grows TMDC nanotubes
What makes a material worth pursuing for three decades? For TMDC nanotubes — atom-thin cylinders with exotic quantum properties — the answer was always “whatever we can make.” Scientists could grow them, but they couldn’t control their shape. And shape, at the atomic scale, determines everything.
Transition metal dichalcogenide (TMDC) nanotubes are one-dimensional crystals with properties that conventional materials don’t have — quantum confinement effects, van Hove singularities, and unusual electronic and optical behaviors. The family includes molybdenum disulfide, tungsten disulfide, tin disulfide, and many others. First discovered in 1992, TMDCs have tantalized material scientists for decades with their theoretical potential. The problem: nobody could reliably synthesize them with the right chirality — the atomic-level twist that defines a nanotube’s electronic character.
A team led by Zhejiang University has finally cracked it.
Xiang Rong’s group at the university’s Atomic-level Materials Manufacturing Lab, working with collaborators from Dalian University of Technology, Westlake University, Suzhou Laboratory, Peking University, Osaka University, and the University of Tokyo, demonstrated the first-ever chiral-controlled synthesis of TMDC nanotubes. They achieved selective growth of armchair-type nanotubes — the configuration that happens to be the most useful for electronics.
The trick was to use boron nitride nanotubes as a mold. By growing TMDC material inside the hollow channel of a boron nitride template, the team found that the inner wall first forms a zigzag-shaped nanobelt. Under the confinement of the mold and the vibration of the tube walls, the nanobelt slides, closes at the edges, and rolls itself into an armchair nanotube. The mechanism was confirmed using real-time transmission electron microscopy — the team literally filmed the nanobelt rolling up.
For tin disulfide, this method yielded up to 84% armchair-type nanotubes. Molybdenum disulfide and tungsten disulfide showed similarly strong armchair preferences.
The result was so unexpected that reviewers demanded more data.
“We submitted 50 sets with our first draft, but the conclusion seemed too surprising to believe,” said Zheng Yongjia, a researcher at Zhejiang University’s mechanical engineering school. “So three of us worked in shifts — 72 hours straight, machines running non-stop — and collected 300 more data sets. The results matched perfectly. That convinced the reviewers.”
Armchair TMDC nanotubes have lower effective electron mass and higher carrier mobility than their zigzag counterparts, making them natural candidates for nanoscale transistors and high-speed electronic devices. Before this work, researchers could only grow a mix of chiralities and hope for the best.
The paper was published in Science as a First Release on July 17.