Synthesis of Hundred-Micrometer-Scale Single-Crystalline Carbon Nanothreads - Drs. Kuo Li and Haiyan Zheng

New research from a team led by Drs. Kuo Li and Haiyan Zheng at the Center for High Pressure Science and Technology Advanced Research (HPSTAR), in collaboration with researchers from Tsinghua University and other institutions, reports a major breakthrough in carbon nanothreads (CNThs) published in the journal Chem. The team successfully synthesized hundred-micrometer-scale single-crystal carbon nanothreads via a single-crystal-to-single-crystal transformation of 1-naphthoic acid under high pressure. The resulting CNTh single crystals exhibit nearly zero axial compressibility and exceptionally strong anisotropic thermal conductivity, highlighting their great potential for applications in next-generation high-performance nanoelectronic devices and related fields.

Carbon nanothreads are one-dimensional, diamond-like nanomaterials only a few carbon atoms thick. They uniquely combine diamond’s “hard-core” properties—ultrahigh mechanical strength and excellent thermal conductivity—with polymer-like flexibility, endowing them with tremendous potential for applications in nanomechanical systems, ultrasensitive sensors, and thermal management in microelectronics. In particular, their intrinsic anisotropic heat-transport capability offers a promising solution to the long-standing challenge of directional heat dissipation in electronic devices, overcoming the performance limitations of conventional thermal materials.

Carbon nanothreads were first observed in 2015 as products of the high-pressure polymerization of benzene. Over the subsequent decade, sustained efforts have been made to improve their structural order. Nevertheless, the fabrication of large-scale, high-quality single-crystal CNThs has remained extremely challenging. Consequently, their outstanding physical properties have not been experimentally verified, and their practical application has remained elusive.

Drs. Li and Zheng have long focused on chemical reactions of unsaturated molecules under high pressure, including the synthesis of CNThs. In recent years, their team has successfully synthesized a variety of ultrathin carbon nanothreads and graphene nanoribbons with atomic-scale ordered structures.

In the present study, the researchers innovatively adopted a “single-crystal-to-single-crystal” topochemical polymerization strategy. By precisely controlling the reaction conditions, they achieved the synthesis of high-quality, hundred-micrometer-scale single-crystal CNThs. The unique carboxyl–carboxyl hydrogen-bonding interactions of 1-naphthoic acid molecules, together with an optimal slip angle of 21.6°, enabled efficient molecular pre-stacking. When combined with the synergistic effects of 20 GPa pressure and annealing at 573 K, defect formation was effectively suppressed, preserving the integrity of the crystal structure during polymerization. Structural characterization revealed that the resulting CNTh single crystals adopt a lonsdaleite-like (hexagonal diamond) structure, with dimensions of 140 × 100 × 20 μm, representing the largest CNTh single crystals reported to date and providing a crucial foundation for macroscopic property measurements. Thermal transport measurements showed that the ratio of thermal conductivity along the nanothread axis to that in the perpendicular direction reaches 84, comparable to that of hexagonal boron nitride and far exceeding that of highly aligned carbon nanotube films (1.2–13.5). Meanwhile, the axial compressibility is nearly zero, whereas the transverse compressibility is 0.013 GPa⁻¹, indicating excellent mechanical stability.

Beyond the successful synthesis of high-performance CNTh single crystals, this work establishes a controllable synthesis paradigm that integrates molecular pre-design, high-pressure topochemical polymerization, and annealing-assisted defect elimination. Through solid-state nuclear magnetic resonance and X-ray pair distribution function analyses, the researchers uncovered the selective reactivity sequence of carbon atoms and elucidated a polymerization mechanism dominated by stepwise Diels–Alder additions, providing theoretical guidance for the rational design and synthesis of low-dimensional carbon materials with tailored structures. Moreover, this study demonstrates, for the first time, the stable retention of CNTh single crystals at ambient pressure, marking a critical step toward their practical application. With further optimization of the synthesis strategy, carbon nanothreads are expected to find broad applications in thermal management systems for communications, quantum computing, and new-energy vehicles, among other advanced technologies.

Caption: Synthesis of single-crystal CNTh from 1-naphthoic acid with high thermal conductivity anisotropy.

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北京高压科学研究中心的李阔、郑海燕课题组以1-萘甲酸作为前驱体，在高压下通过“单晶到单晶”的转变，成功合成出百微米尺度的金刚石纳米线单晶。多种表征技术证明，这种聚1-萘甲酸金刚石纳米线具有类六方金刚石的一维结构，具有线间和线内的高度有序性。2025年12月15日，相关研究成果以“Synthesis of single-crystalline carbon nanothreads from 1-naphthoic acid with high anisotropic thermal conductivity”为题，在线发表于Chem期刊。这种新型碳材料具备高度各向异性的热导率和压缩率。该成果为推动金刚石纳米线走向实际应用迈出了关键一步。