The researchers at Queen Mary University of London, University of Cambridge and Max Planck Institute for Solid State Research have discovered how metal salts can be used to drastically improve the structure of metal organic framework (MOF) materials. These MOFs are attractive, molecularly designed porous materials with many promising applications such as gas storage and separation. The retention of high surface area after carbonisation at a high temperature makes them interesting as electrode materials for batteries and for ultracapacitors. However, so far carbonising MOFs has preserved the structure of the initial particles like that of a dense carbon foam. By adding salts to these MOF sponges and carbonising them, the researchers discovered a series of carbon-based materials with multiple levels of hierarchy.
Due to their intricate architecture the researchers have termed the resulting structures 'nano-diatoms', and believe they could also be used in energy storage and conversion, for example as electrocatalysts for hydrogen production.
"This metamorphosis only happens when we heat the compounds to 800 degrees centigrade and was as unexpected as hatching fire-born dragons instead of getting baked eggs in the Game of Thrones. It is very satisfying that after the initial surprise, we have also discovered how to control the transformations with chemical composition," said lead author and project leader Dr Stoyanoukov, from Queen Mary's School of Engineering and Materials Science. The paper was published in JACS (Journal of the American Chemical Society).
"This work pushes the use of the MOFs to a new level. The strategy for structuring carbon materials could be important not only in energy storage but also in energy conversion, and sensing," said fellow researcher Dr R. Vasant Kumar from the University of Cambridge.