Germanium iodide mediated synthesis of nanodiamonds from adamantane "seeds" under moderate high-pressure high-temperature conditions

There is an emerging demand for nanodiamonds with controlled structures or shapes for applications in biomedical imaging and sensing. Synthetic conditions proceeding at less harsh temperatures and pressures are considered crucial to control nanodiamond formation process. We report a germanium iodide (GeI₄) mediated synthesis of nanodiamonds from diamondoid molecules and alkane hydrocarbon under moderate high-pressure high-temperature (m-HPHT) conditions. For the first time, GeI₄ is used to generate nanodiamonds at 3.5 GPa and 500 °C, which is considerably lower than the conditions reported for common HPHT methods for nanodiamond synthesis. The strategy reported herein allows synthesizing nanodiamonds based on well-defined molecular precursors, which paves the way to a bottom-up diamond synthesis designed at a molecular level.