Carbon Nanotubes as Electrically Active Nanoreactors for Multi-Step Inorganic Synthesis: Sequential Transformations of Molecules to Nanoclusters and Nanoclusters to Nanoribbons.
In organic synthesis, the composition and structure of products are predetermined by the reaction conditions; however, the synthesis of well-defined inorganic nanostructures often presents a significant challenge yielding nonstoichiometric or polymorphic products. In this study, confinement in the nanoscale cavities of single-walled carbon nanotubes (SWNTs) provides a new approach for multistep inorganic synthesis where sequential chemical transformations take place within the same nanotube. In the first step, SWNTs donate electrons to reactant iodine molecules (I2), transforming them to iodide anions (I(-)). These then react with metal hexacarbonyls (M(CO)6, M = Mo or W) in the next step, yielding anionic nanoclusters [M6I14](2-), the size and composition of which are strictly dictated by the nanotube cavity, as demonstrated by aberration-corrected high resolution transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive X-ray spectroscopy. Atoms in the nanoclusters [M6I14](2-) are arranged in a perfect octahedral geometry and can engage in further chemical reactions within the nanotube, either reacting with each other leading to a new polymeric phase of molybdenum iodide [Mo6I12]n or with hydrogen sulfide gas giving rise to nanoribbons of molybdenum/tungsten disulfide [MS2]n in the third step of the synthesis. Electron microscopy measurements demonstrate that the products of the multistep inorganic transformations are precisely controlled by the SWNT nanoreactor with complementary Raman spectroscopy revealing the remarkable property of SWNTs to act as a reservoir of electrons during the chemical transformation. The electron transfer from the host nanotube to the reacting guest molecules is essential for stabilizing the anionic metal iodide nanoclusters and for their further transformation to metal disulfide nanoribbons synthesized in the nanotubes in high yield.
School of Chemistry, University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom.
Akos
A
Botos
Central Facility of Electron Microscopy, Electron Microscopy Group of Materials Science , Albert-Einstein-Allee 11, D-89081 Ulm, Germany.
Johannes
J
Biskupek
School of Chemistry, University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom.|Institute of Process Research Development, School of Chemistry, University of Leeds , Leeds LS2 9JT, United Kingdom.
Thomas W
TW
Chamberlain
School of Chemistry, University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom.
Graham A
GA
Rance
School of Chemistry, University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom.
Craig T
CT
Stoppiello
Warwick Centre for Analytical Science, Department of Physics, University of Warwick , Coventry CV4 7AL, United Kingdom.
Jeremy
J
Sloan
Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba 305-8565, Japan.|Inorganic Functional Materials Research Institute National, Institute of Advanced Industrial Science and Technology (AIST) , Nagoya 463-8560, Japan.
Zheng
Z
Liu
Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) , Tsukuba 305-8565, Japan.
Kazutomo
K
Suenaga
Central Facility of Electron Microscopy, Electron Microscopy Group of Materials Science , Albert-Einstein-Allee 11, D-89081 Ulm, Germany.
Ute
U
Kaiser
School of Chemistry, University of Nottingham , University Park, Nottingham NG7 2RD, United Kingdom.
Andrei N
AN
Khlobystov