Recently, a research team led by Eiichi Nakamura, Chair Professor at Nankai University, published their latest findings titled “Rapid, Low-temperature Nanodiamond Formation by Electron-beam Activation of Adamantane C–H Bonds” in Science.

Professor Nakamura’s team utilized an organic molecular precursor with a cage-like diamondoid framework containing 10 carbon atoms. By applying electron-beam irradiation for seconds to minutes under vacuum conditions at room temperature or lower, they successfully synthesized spherical single-crystalline nanodiamonds with uniform size and highly ordered morphology. Nanodiamonds have been proven applicable in critical fields such as quantum sensing and drug delivery, opening new avenues for future applications of related materials.

Schematic Diagram of Monocrystalline Nanodiamond Synthesis

Using atomic-resolution transmission electron microscopy, the team achieved synthesis of spherical nanodiamonds (ND) via electron-beam irradiation on adamantane crystals with diamond framework structures. Whereas conventional diamond synthesis requires extremely harsh conditions, this work utilized radical cations of adamantane molecules as key intermediates to accomplish synthesis within minutes under mild conditions (−173 °C to room temperature, 10^-5 Pa). Notably, in-situ observation and reaction kinetics analysis confirmed the successful production of nanodiamonds with highly uniform particle sizes (2–8 nm) and yields approaching 100%. Importantly, the study identified C–H bond cleavage as the rate-determining step and demonstrated that the resulting diamond surfaces are hydrogen-terminated. This electron-beam–driven precision organic synthesis thus establishes a new reaction pathway for diamond formation.

Eiichi Nakamura, Chair Professor at Nankai University and Special Professor at the University of Tokyo’s Department of Chemistry, served as one of the corresponding authors, with Nankai University listed as a corresponding affiliation.

Full Paper available at: https://www.science.org/doi/10.1126/science.adw2025

（Edited and translated by Nankai News Team.)