Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Electrochemical opening of single-walled carbon nanotubes filled with metal halides and with closed ends
AU - Holloway, Andrew F.
AU - Toghill, Kathryn
AU - Wildgoose, Gregory G.
AU - Compton, Richard G.
AU - Ward, Michael A. H.
AU - Tobias, Gerard
AU - Llewellyn, Simon A.
AU - Ballesteros, Belen
AU - Green, Malcolm L. H.
AU - Crossley, Alison
PY - 2008/7/17
Y1 - 2008/7/17
N2 - The electrochemical opening of closed-ended, pristine single-walled carbon nanotubes (SWCNTs) upon the application of either a sufficiently oxidizing or reducing electrode potential is reported. Hitherto, it has been unclear whether the side walls of SWCNTs are electrochemically active, or whether, like their multiwalled counterparts (MWCNTs), the electroactive sites on SWCNTs also reside at the edge-plane-like defects at the open ends of the tubes. Evidence is presented herein that suggests the latter case is true, i.e., that SWCNTs require edge-plane sites to be electroactive. Comparisons of the voltammetric response of end-closed SWCNTs (EC-SWCNTs), end-open (EO-SWCNTs), and SWCNTs encapsulating a metal halide filling (MX@SWCNTs, where MX represents either NaI or CuI) in aqueous electrolytes indicate that SWCNTs undergo electrochemical opening if the applied electrode potential is greater than +1.2 V vs SCE or less than -1.5 V vs SCE. This was further confirmed using ex situ X-ray photoelectron spectroscopy. The nonaqueous voltammetry of NaCl@SWCNTs, NaI@SWCNTs, CuI@SWCNTs, and ZnCl2@SWCNTs in dimethyl formamide (DMF) containing 0.1 M tetrabutyl ammonium perchlorate (TBAP) all exhibited voltammetric responses identical to that of EC-SWCNTs unless the potential was cycled beyond ca. +1.6 V vs Ag (+2.129 V vs the cobaltocene/cobaltocenium redox couple) whereupon voltammetry corresponding to the filling material was observed, again indicating that the SWCNTs had become open-ended. Evidence for quantized charging of the EC-SWCNTs is presented in terms of the unusual "bow-tie" shape of the background charging current in DMF is also presented.
AB - The electrochemical opening of closed-ended, pristine single-walled carbon nanotubes (SWCNTs) upon the application of either a sufficiently oxidizing or reducing electrode potential is reported. Hitherto, it has been unclear whether the side walls of SWCNTs are electrochemically active, or whether, like their multiwalled counterparts (MWCNTs), the electroactive sites on SWCNTs also reside at the edge-plane-like defects at the open ends of the tubes. Evidence is presented herein that suggests the latter case is true, i.e., that SWCNTs require edge-plane sites to be electroactive. Comparisons of the voltammetric response of end-closed SWCNTs (EC-SWCNTs), end-open (EO-SWCNTs), and SWCNTs encapsulating a metal halide filling (MX@SWCNTs, where MX represents either NaI or CuI) in aqueous electrolytes indicate that SWCNTs undergo electrochemical opening if the applied electrode potential is greater than +1.2 V vs SCE or less than -1.5 V vs SCE. This was further confirmed using ex situ X-ray photoelectron spectroscopy. The nonaqueous voltammetry of NaCl@SWCNTs, NaI@SWCNTs, CuI@SWCNTs, and ZnCl2@SWCNTs in dimethyl formamide (DMF) containing 0.1 M tetrabutyl ammonium perchlorate (TBAP) all exhibited voltammetric responses identical to that of EC-SWCNTs unless the potential was cycled beyond ca. +1.6 V vs Ag (+2.129 V vs the cobaltocene/cobaltocenium redox couple) whereupon voltammetry corresponding to the filling material was observed, again indicating that the SWCNTs had become open-ended. Evidence for quantized charging of the EC-SWCNTs is presented in terms of the unusual "bow-tie" shape of the background charging current in DMF is also presented.
KW - IN-SITU RAMAN
KW - ELECTRON-TRANSFER KINETICS
KW - PLANE PYROLYTIC-GRAPHITE
KW - FULLERENE PEAPODS
KW - CHARGE-TRANSFER
KW - REACTIVE SITES
KW - C-60 PEAPODS
KW - TUBE ENDS
KW - SPECTROELECTROCHEMISTRY
KW - NIR
U2 - 10.1021/jp802127p
DO - 10.1021/jp802127p
M3 - Journal article
VL - 112
SP - 10389
EP - 10397
JO - The Journal of Physical Chemistry C
JF - The Journal of Physical Chemistry C
SN - 1932-7447
IS - 28
ER -