(237a) Mechanochemistry for Material Synthesis: Old Is New Again

Mechanochemistry describes that mechanical force induces chemical transformation. Ball-milling is the most widely used process, in which high speed traveling metal balls deliver enough kinetic energy to cause mechanical breakage, activating the surface of materials. In this talk, I would like to introduce mechanochemistry for edge-selectively functionalized graphitic nanoplatelets (EFGnPs),^[1,2] nitrogen dissociation,^[3] ammonia synthesis,^[4] and heterophase reaction.^[5] We realized an edge-selective functionalization of graphitic nanoplatelets via ball-milling for the first time. Mechanical force induces cracking graphitic framework, generating active carbon species (mostly carboradicals) along the unzipped edges. These active carbon species react with any substant (e.g., carbon dioxide) present in the system, imparting functionalization, and delamination at the same time to yield various EFGnPs.^[1,2] Using ball-milling, stable diatomic nitrogen can be dissociated and fixed on the surface of EFGnPs.^[3] A sequential ball-milling iron powder in nitrogen and hydrogen atmospheres produces ammonia.^[4] Last but not least, ball-milling carbon materials in the presence of hydrogen can efficiently produce hydrocarbons at ambient conditions.^[5]

References:

1. Jeon, et al. Edge-carboxylated graphene nanosheets via ball-milling. Proceedings of the National Academy of Sciences of the United States of America 2012, 109, 5588.
2. Han, et al. Building and identifying highly active oxygenated groups in carbon materials for oxygen reduction to H₂O₂. Nature Communications 2020, 11, 2209.
3. Han, et al. Dissociating stable nitrogen molecules under mild conditions by cyclic straining engineering. Science Advances 2019, 5, eaax8275.
4. Han, et al. Mechanochemistry for ammonia synthesis under mild conditions. Nature Nanotechnology 2021, 16, 325.
5. Han, et al. Mechanochemistry for heterophase reaction. Unpublished Result 2021.