Single-Walled Carbon Nanotube Reactor for Redox Transformation of Mercury Dichloride

Abstract

Single-walled carbon nanotubes (SWCNTs) possessing a confined inner space protected by chemically resistant shells are promising for delivery, storage, and desorption of various compounds, as well as carrying out specific reactions. Here, we show that SWCNTs interact with molten mercury dichloride (HgCl) and guide its transformation into dimercury dichloride (HgCl) in the cavity. The chemical state of host SWCNTs remains almost unchanged except for a small p-doping from the guest HgCl nanocrystals. The density functional theory calculations reveal that the encapsulated HgCl molecules become negatively charged and start interacting via chlorine bridges when local concentration increases. This reduces the bonding strength in HgCl, which facilitates removal of chlorine, finally leading to formation of HgCl species. The present work demonstrates that SWCNTs not only serve as a template for growing nanocrystals but also behave as an electron-transfer catalyst in the spatially confined redox reaction by donation of electron density for temporary use by the guests.

Enter the Tubes: Carbon Nanotube Endohedral Catalysis

“…Although very powerful, the effect of CNTs is not limited to templating. Toxic, water-soluble HgCl 2 was transformed into Hg 2 Cl 2 within CNTs, with the latter contributing to the transformation via electron transfer pathways, donating electron density [50]. Functional groups pendant to carbons have also exploited for the same redox reaction [51], with the consequent oxidation of the carbon material.…”

Characterization of the Electronic Properties of Single‐Walled Carbon Nanotubes Filled with an Electron Donor—Rubidium Iodide: Multifrequency Raman and X‐ray Photoelectron Spectroscopy Studies

“…Despite the fact that many works reported the Raman spectroscopy studies on SWCNTs filled with electron acceptors and common doping‐induced trends in changing Raman modes were revealed, there are only a few reports on the Raman spectroscopy studies of SWCNTs filled with electron donors using a limited number of laser wavelengths. In Refs.…”

“…The SWCNTs can be filled with different simple substances, chemical compounds, and molecules possessing appropriate chemical and physical properties. It was demonstrated that metals and some organic and organometallic molecules result in n‐doping of SWCNTs, whereas metal halogenides lead to p‐doping of nanotubes.…”

“…In the literature, there are reports on the studies of the electronic properties of SWCNTs filled with halogenides of 3d‐ (Mn, Fe, Co, Ni, Zn, Cu), 4d‐ (Ag, Cd), 5d‐ (Hg), and 4f‐metals (Tb, Pr, Tm) . The valuable experimental data on the modification of the electronic properties of SWCNTs due to the filling were obtained.…”

Synthesis and Properties of Single-Walled Carbon Nanotubes Filled with Metal Halogenides and Metallocenes

“…In the literature, there are the reports on the investigation of the electronic properties of SWCNTs filled with MnCl 2 , MnBr 2 [45,46], FeCl 2 , FeBr 2 , FeI 2 [47], CoBr 2 [48], NiCl 2 [49], NiBr 2 [49,50], CuCl [51,52], CuBr [51], CuI [51,53,54], ZnCl 2 [55,56], ZnBr 2 , ZnI 2 [55], RbI, RbAg 4 I 5 [57], AgCl [58][59][60][61], AgBr, AgI [58], CdCl 2 [56,62,63], CdBr 2 , CdI 2 [62], SnF 2 [64], TbCl 3 [56,65,66], TbBr 3 , TbI 3 [66], PrCl 3 [65,67], ErCl 3 [68], TmCl 3 [65,69], and HgCl 2 [70]. The characterization of the electronic properties of the filled SWCNTs was performed by three main techniques: OAS, Raman spectroscopy, and XPS.…”