TY - JOUR

T1 - Ring current effects

T2 - factors affecting the NMR chemical shift of molecules adsorbed on porous carbons

AU - Forse, Alexander C.

AU - Griffin, John M.

AU - Presser, Volker

AU - Gogotsi, Yury

AU - Grey, Clare P.

PY - 2014/4/10

Y1 - 2014/4/10

N2 - Nuclear magnetic resonance (NMR) spectroscopy is increasingly being used to study the adsorption of molecules in porous carbons, a process which underpins applications ranging from electrochemical energy storage to water purification. Here we present density functional theory (DFT) calculations of the nucleus-independent chemical shift (NICS) near various sp(2)-hybridized carbon fragments to explore the structural factors that may affect the resonance frequencies observed for adsorbed species. The domain size of the delocalized electron system affects the calculated NICSs, with larger domains giving rise to larger chemical shieldings. In slit pores, overlap of the ring current effects from the pore walls is shown to increase the chemical shielding. Finally, curvature in the carbon sheets is shown to have a significant effect on the NICS. The trends observed are consistent with existing NMR results as well as new spectra presented for an electrolyte adsorbed on carbide-derived carbons prepared at different temperatures.

AB - Nuclear magnetic resonance (NMR) spectroscopy is increasingly being used to study the adsorption of molecules in porous carbons, a process which underpins applications ranging from electrochemical energy storage to water purification. Here we present density functional theory (DFT) calculations of the nucleus-independent chemical shift (NICS) near various sp(2)-hybridized carbon fragments to explore the structural factors that may affect the resonance frequencies observed for adsorbed species. The domain size of the delocalized electron system affects the calculated NICSs, with larger domains giving rise to larger chemical shieldings. In slit pores, overlap of the ring current effects from the pore walls is shown to increase the chemical shielding. Finally, curvature in the carbon sheets is shown to have a significant effect on the NICS. The trends observed are consistent with existing NMR results as well as new spectra presented for an electrolyte adsorbed on carbide-derived carbons prepared at different temperatures.

KW - SOLID-STATE NMR

KW - NUCLEAR-MAGNETIC-RESONANCE

KW - CARBIDE-DERIVED CARBON

KW - ACTIVATED CARBON

KW - CURRENT DENSITIES

KW - ADSORPTION

KW - SPECTROSCOPY

KW - ELECTROLYTE

KW - STORAGE

KW - CHARGE

U2 - 10.1021/jp502387x

DO - 10.1021/jp502387x

M3 - Journal article

VL - 118

SP - 7508

EP - 7514

JO - The Journal of Physical Chemistry C

JF - The Journal of Physical Chemistry C

SN - 1932-7447

IS - 14

ER -