✍ Scribed by Toshihiro Horibe; Jingdong Zhang; Munetaka Oyama
No coin nor oath required. For personal study only.
For evaluating the effects of capping reagents on the electron transfer reactions on gold nanoparticles (AuNPs), AuNP‐attached indium tin oxide (AuNP/ITO) substrates were fabricated using a seed mediated growth method. In addition to the previous procedures, i.e., the crystal growth of AuNPs on ITO in the presence of cetyltrimethylammonium bromide (CTAB) as a capping reagent in the growth solution, the preparation in the presence of sodium dodecyl sulfate (SDS) was examined to find that the fabrication of AuNP/ITO was also possible with SDS. Systematic measurements of cyclic voltammograms were carried out using the AuNP/ITO electrodes prepared with different surfactants, i.e., cationic CTAB and anionic SDS, for the oxidation of anionic [Fe(CN)~6~]^4−^ and the reduction of cationic [Ru(NH~3~)~6~]^3+^. The results showed that the electrochemical responses were significantly improved on the AuNP/ITO electrodes, not depending on the charges of the capping surfactants and the redox species. Thus, the capping of CTAB and SDS on AuNP/ITO was concluded to be quite weak or less, so that the electron transfer reactions of both [Fe(CN)~6~]^4−^ and [Ru(NH~3~)~6~]^3+^ were not disturbed. The weak or less capping of CTAB and SDS was confirmed by replacing to 3‐mercaptopropionic acid. Compared with thiols, the capping with surfactants would be useful in electroanalysis, in particular, of biomolecules, utilizing naked or undisturbed surfaces of AuNPs.
📜 SIMILAR VOLUMES
The apparent heterogeneous rate constants can be determined by a special cu technique in solutions containing both the oxidized and the reduced forms of a redox couple. The electrode materials are characterized by the dikence between the ktX and kFed. The effect of RuO,/IiO, ratio on the electrochem