The photo is sourced from news.tpu.ru
Metal-organic frameworks (MOFs) are crystalline porous materials consisting of metal ions bound together by organic molecules. Essentially, MOFs are crystalline structures, in which metals and organics form a network whose pores can change under high temperatures. As a result, one can place molecules of external compounds inside the MOFs and later release them when external conditions change.
The scientists from Tomsk Polytechnic University took advantage of this feature of MOFs and developed a material for hydrogen storage using metal-organic frameworks based on chromium, as well as magnesium hydride, a chemical compound that can hold hydrogen in a bound chemical form at a temperature of 400 degrees Celsius. The synthesising of these two components resulted in the formation of a composite material that can hold hydrogen at a much lower temperature (260 degrees Celsius). This innovation presents an alternative to the traditional method of storing hydrogen in compressed form and under high pressure.
During the experiment, the scientists found that the resulting composite is a core/shell structure: magnesium hydride particles are coated with disproportionate chromium particles, which, in turn, defines the key properties of the material.
“On the one hand, chromium nanoparticles have a catalytic effect. It is not through the magnesium surface but through chromium particles that hydrogen penetrates into the composite, because it needs less energy to interact with chromium. This is due to a decrease in the dissociation energy of hydrogen molecules. On the other hand, defects formed in magnesium hydride during joint mechanochemical treatment with metal-organic frameworks based on chromium help improve the sorption and desorption properties of the composite,” Roman Laptev, associate professor at the Division for Experimental Physics of the School of Nuclear Science and Engineering, is quoted as saying by Tomsk Polytechnic University.
The authors of the study plan to further reduce the temperature, at which the new material can absorb and desorb hydrogen. This should facilitate the successful commercialisation of the solution.