Gold Nanoelectrodes of Varied Size: Transition to Molecule-Like Charging
Shaowei Chen,
Roychelle S. Ingram,
Michael
J. Hostetler,
Jeremy J. Pietron,
Royce W. Murray,
*
T. Gregory Schaaff,
Joseph T. Khoury,
Marcos M. Alvarez,
Robert L. Whetten
*
A transition from metal-like double-layer capacitive charging to
redox-like charging was observed in electrochemical ensemble Coulomb
staircase experiments on solutions of gold nanoparticles of varied core
size. The monodisperse gold nanoparticles are stabilized by short-chain
alkanethiolate monolayers and have 8 to 38 kilodaltons core mass (1.1 to 1.9 nanometers in diameter). Larger cores display Coulomb staircase
responses consistent with double-layer charging of metal-electrolyte
interfaces, whereas smaller core nanoparticles exhibit redox chemical
character, including a large central gap. The change in behavior is
consistent with new near-infrared spectroscopic data showing an
emerging gap between the highest occupied and lowest unoccupied
orbitals of 0.4 to 0.9 electron volt.
S. Chen, R. S. Ingram, M. J. Hostetler, J. J. Pietron, R. W. Murray, Department of Chemistry, Kenan
Laboratories, University of North Carolina, Chapel Hill, NC
27599-3290, USA.
T. G. Schaaff, J. T. Khoury, M. M. Alvarez, R. L. Whetten, Schools of Chemistry and Physics, Georgia Institute of
Technology, Atlanta, GA 30332-0430, USA.
*
To whom correspondence should be addressed. E-mail:
rwm{at}email.unc.edu (R.W.M.) or
robert.whetten{at}physics.gatech.edu (R.L.W.)
