Highly resolved quantized double-layer charging of relatively larger dodecanethiol-passivated gold quantum dots

Monolayer-protected quantum dots (Q-dots) show multivalent redox property, popularly known as the quantized double-layer (QDL) charging phenomena. In this report, we demonstrate the QDL behavior of the larger-sized Au Q-dots (ca. 3.72 nm) protected with dodecanethiol using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The voltammetric results show that the QDL property is evident even for these larger-sized Q-dots as reflected by a large population of well-resolved charging events in a narrow potential range with an almost equidistant voltage (DeltaV) spacing. The theoretical calculation of the variation of charging energy with size using the well-known concentric sphere capacitance model facilitates the understanding of electrochemical behavior of these sidelined larger-sized Au Q-dots. The calculated capacitance value is in well agreement with the experimentally obtained value of 1.6 aF. (C) 2004 American Institute of Physics.