Mechanochemical Synthesis of Carbon and Carbon Nitride Nanothread Single Crystals*

A new type of 1D sp³ carbon nanomaterial, carbon nanothreads, was recently reported (Nat. Mater., 2015). Modeling suggests “diamond” nanothreads may uniquely combine extreme strength with flexibility and resilience. They are synthesized by compressing benzene slowly in Paris-Edinburgh (PE) cell. After optimizing the synthetic conditions, we now report the synthesis of single crystals of these nanothreads in both PE and diamond anvil cells (JACS, 2017); their single crystal nature allows them to exfoliate into fibers. Exfoliation into individual threads that might be assembled into functional materials may be possible. We also synthesized carbon nitride nanothreads from pyridine by the same kinetically controlled approach. Tuning the chemical composition by the methods of organic chemistry allows for flexible design of properties such as bandgap, solubility etc. We investigated the composition and structure of these diamond and carbon nitride nanothread crystals by NMR, x-ray diffraction, XPS, and vibrational spectroscopies. Synthesis of a large new family of carbon nanomaterials by the slow compression methods used for the synthesis of benzene nanothreads appears plausible.