September 8th
when: Tuesday 08/09/2020, 12:45
where: KE D201 and Zoom meeting!
speaker: Nikola Biliskov
title: Mechanochemical pathway from reagents to energy-related materials. What happens inside the milling jar?
abstract:
Mechanochemical reactions conducted by milling achieve a chemical transformation upon applying mechanical force. They have tremendously gained in popularity over the recent years due to them offering novel, and sometimes unprecedented, aspects of chemical reactivity as compared to traditional solution-based chemistry. Mechanochemical reactions do not require dissolution to achieve the desired chemical reaction rendering them inherently solvent-free. The milling jar is loaded with one, two or many balls, usually made from stainless steel or some ceramic material, as the milling media, which transfer mechanical energy of the moving milling assembly to the reaction mixture, which is then said to be milled. One particular benefit of mechanochemistry is its scalability, from laboratory to industrial scale. In recent years, mechanochemistry has moved into areas that study weak chemical interactions such as supramolecular chemistry and molecular recognition, as well as metal-organic compounds and materials. On the other hand, the solvent-free nature of milling reactions increases their ecological potential that could be exploited in chemical industry, which currently bears a strong impact on the environment. Thus, using no solvent presents a qualitative step further in developing clean and resource-efficient manufacturing. What is still missing in mechanochemistry is deeper understanding of underlying mechanisms that govern mechanochemical transformations, which is essential for further advance of mechanochemistry to acquire knowledge and understanding of reaction mechanisms at the molecular level and to decouple the effect of ball impacts and material compression on reaction progress from mere mixing achieved by the movement of milling media. To address these issues methods of in situ reaction monitoring of reacting solids are crucial. Here, a few examples of in-situ monitorings by means of XRD, Raman spectroscopic and temperature measurements of mechanochemical preparations of energy-related materials, especially those for hydrogen storage, will be presented.