Unexpected results could lead to room temperature production of new materials that change how we produce, store, and use energy. Pressure, not heat, is the key. An interdisciplinary team subjected acetonitrile, a stable compound containing carbon, hydrogen and nitrogen atoms, to high pressure at room temperature. The result? A layered polymer carbon akin to graphene. The team from Oak Ridge National Lab, the Center for High Pressure Science &Technology Advanced Research in Beijing, and the Carnegie Institution of Washington were surprised to find this catalyst-free method also produced ammonia.
The finding opens the door for new ways to synthesize carbon nanomaterials at low temperature. It also sheds light on possible natural chemical processes on distant planets as well as comets and meteors.
Extreme pressure can determine the chemical evolution of inorganic and organic carbon-based molecules. Neutron scattering experiments combined with Fourier-transform infrared Raman and solid-state nuclear magnetic resonance spectroscopy revealed a room-temperature method for making a polymer from a simple acetonitrile precursor, without a catalyst, by employing high pressure (>25 gigapascals, or about that found 650 kilometers below the Earth’s surface). Reactions with acetonitrile usually require a strong base and metal catalyst. The catalyst-free method “squeezed” chemicals to break stable bonds between carbon and hydrogen atoms, transferred hydrogen from carbon to nitrogen, and formed an amino group, dimer, chain, and nanoribbon. Then ammonia was ejected to create a graphene-like structure. Thus, using high pressure—rather than high temperature—opened the door to new opportunities for synthesizing carbon nanomaterials at room temperature without a traditional chemical catalyst. Intriguingly, because acetonitrile is found in space, catalyst-free, high-pressure chemistry suggests it may be possible to discover complex hydrocarbon-containing compounds in impact craters of distant planets.
This work was done in collaboration with researchers from the Energy Frontier Research in Extreme Environment Center (EFree), which funded the work of H.Z., K. L., W.Y, and M.G. EFree is funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences under grant DE-SC0001057. The authors acknowledge the support of the National Natural Science Associated Foundation of China(grant U1530402) and National Natural Science Foundation of China (grant 21501162). Additional funding came from the National Secretariat of Higher Education, Science, Technology and Innovation of Ecuador. The research at Oak Ridge National Lab’s Spallation Neutron Source and Center for Nanophase Materials Sciences was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, DOE, Office of Science. The research also used Brookhaven National Laboratory’s beamline U2A, which is supported by the U.S. National Science Foundation (Earth Sciences) 1606856, Consortium for Materials Properties Research in Earth Sciences, and the DOE/National Nuclear Security Administration (DE-NA-0002006, Carnegie/Department of Energy Alliance Center).
H. Zheng, K. Li, G.D. Cody, C.A. Tulk, X. Dong, G. Gao, J.J. Molaison, Z. Liu, M. Feygenson, W. Yang, I.N. Ivanov, L. Basile, J.C. Idrobo, M. Guthrie, and H.K. Mao, “Polymerization of acetonitrile via a hydrogen transfer reaction from CH3 to CN under extreme conditions.” Angewandte Chemie International Edition 55, 12040-12044 (2016). [DOI: 10.1002/anie.201606198]