%0 Journal Article
%T Electron Transfer at Gold Nanostar Assemblies: A Study of Shape Stability and Surface Density Influence
%A Mariana Chirea
%J Catalysts
%D 2013
%I MDPI AG
%R 10.3390/catal3010288
%X Gold nanostars of ~70 nm tip to tip distances were synthesized by a seed mediated method and covalently self-assembled on 1,5-pentanedithiol modified electrodes. Electron transfer kinetics at the AuNS/dithiol modified electrodes were studied as a function of AuNS surface density which was varied by increasing their self-assembly time from 8 h, 16 h, 24 h to 32 h. Excellent electrocatalytic properties of AuNSs were observed toward electrochemistry of [Fe(CN) 6] 4£¿/3£¿ redox couple. The apparent heterogeneous electron transfer constant, k et, has progressively increased with the surface density of AuNSs bonded to the electrodes from 0.65 ¡Á 10 £¿5 cm s £¿1 (8 h), 1.47 ¡Á 10 £¿5 cm s £¿1 (16 h), 3.95 ¡Á 10 £¿5 cm s £¿1 (24 h) to an excellent 85.0 ¡Á 10 £¿5 cm s £¿1 (32 h). Electrochemical charging of nanostars was confirmed, for the first time, by 79 times increase of double layer capacitance, C dl, from 0.34 ¦ÌF (8 h) to 27 ¦ÌF (32 h). The electrochemical charging of AuNSs had also a strong influence on the electron tunneling process through the 1,5PDT molecules being more efficient at dense layers of AuNSs. The tunneling parameter, ¦Â, has decreased from 1.13 £¿ £¿1 (16 h) to 0.50 £¿ £¿1 (32 h). The AuNSs were chemically stable toward [Fe(CN) 6] 4£¿/3£¿ showing no change in shape after electrochemical measurements.
%K molecular electronics
%K gold nanostars
%K electron transfer
%K electrochemical charging
%U http://www.mdpi.com/2073-4344/3/1/288