Nanodiamonds by molecular design

Max Planck Institute for Polymer Research

Versatile Nanodiamonds: Diamond particles of only a few nanometres in size could be used in quantum technologies, sensing and biomedical research.

New production method: A team led by the Max Planck Institute for Polymer Research has found a way to synthesize nanodiamonds from graphene scraps.

Custom-made particles: The new synthesis method makes it possible to precisely control the size and properties of the diamonds.

Nanodiamonds can be used as tiny light sources, as highly sensitive sensors for magnetic fields, or as computing elements in a quantum computer. Now they can be custom-made to the desired size and with the required chemical composition. An international research team led by Yingke Wu and Professor Tanja Weil at the Max Planck Institute for Polymer Research has now developed a new synthesis strategy, which was published in Nature: instead of breaking larger diamonds down into smaller particles, the team builds nanodiamonds from the bottom up using molecularly defined nanographene building blocks. Under high pressure and at high temperatures, these flat carbon molecules are directly converted into diamond-like, highly crystalline nanostructures.

The key advantage of this bottom-up approach lies in its control at the molecular level. Because the structure, size and composition of the starting molecules are precisely defined, the properties of the resulting nanodiamonds can be controlled much more effectively than with conventional milling or top-down methods. Using this strategy, the team was able to produce particularly small, uniform nanodiamonds measuring around three to four nanometres.

Custom made nanodiamonds for various applications

Another important aspect is that optically active colour centres can be incorporated into the diamond lattice directly during synthesis. By using suitable molecular precursors, silicon- and germanium-based emitters can be generated without the need for subsequent ion implantation, irradiation or further post-treatment. This makes it possible to produce fluorescent nanodiamonds with tailored optical properties in a single synthesis step. “We believe this platform offers a scalable foundation for developing quantum sensors, integrated photonic emitters and programmable diamond-based nanomaterials,” says Tanja Weil.

The new molecular nanodiamonds open up promising opportunities for applications in quantum technology, for example as stable single-photon sources or nanoscale sensors. They are also of interest for biological and medical research: in the long term, they could serve as robust optical reporters to visualise processes in cells or other biological environments at the smallest scales.