Source: BAM
Solvents are one of the biggest waste streams in the chemical industry and pose a significant threat to both environmental and public health. In this regard, mechanochemical technologies are being heralded as transformative methods for chemical and materials manufacture. Unlike typical chemistry, mechanochemical reactions use mechanical force to drive chemical reactions without the need for solvent, making chemistry safer, cleaner, and cheaper. Despite the promise of these new technologies, very little is known about how mechanochemical processes work. Without this understanding it is not possible to design a mechanochemical strategy, hindering the game-changing potential of mechanochemistry.
To study mechanochemical reactions new analytical techniques are needed to probe them as they happen. Time-resolved in situ (TRIS) X-ray diffraction (XRD) – a technique pioneered by the BAM–University of Birmingham (UoB) collaboration (1) (2) – has been a big step in this direction. Unfortunately, XRD only gives a small piece of information about how reactions proceed. In fact, XRD (and other TRIS methods) remains blind to very important phenomena such as how the electronic structure changes in materials during a reaction. These changes in electronic structure underpin all chemistry, and techniques capable of following them are essential for understanding mechanochemistry.
The BAM-UoB team has now developed a new analytical tool based on X-ray absorption spectroscopy (XAS), a method that measures a material’s electronic structure. By developing a custom-built spectrometer – developed by BAM at the BAMline, BESSY-II, Helmholtz Zentrum Berlin – the team showed for the first time how material electronic structure can be followed in real time during mechanochemical processes with time resolution that is competitive with state-of-the-art TRIS methods. The team showed that their method is suitable for studying mechanochemical reactions in new reactors (Resonant Acoustic Mixer) and conventional ball mills, and is applicable to various material syntheses, including nanoparticle and metal-organic framework mechanosynthesis
This TRIS-XAS technique is expected to be an integral piece of the toolbox for studying sustainable mechanochemical reactions and will be essential for making mechanochemistry a global standard for green chemistry.
(1) G.I. Lampronti, et al., Nat. Commun., 2021, 12, 6134.
(2) A. A. L. Michalchuk and F. Emmerling, Angew. Chem. Int. Ed., 2022, 61, anie.202117270.
Dispersive x-ray absorption spectroscopy for time-resolved in situ monitoring of mechanochemical reactions
Ana Guilherme Buzanich, C. Tufan Cakir, Martin Radtke, M. Bilal Haider, Franziska Emmerling, Paulo F. M. de Oliveira and Adam A. L. Michalchuk
Published in The Journal of Chemical Physics, Vol. 157, issue 21, article number 214202, pages 1-12, 2022.
BAM Department Materials Chemistry
BAM Division Structure Analysis