The Initial Transformation Mechanism of Gold Seeds on Indium Tin Oxide Surfaces

Abstract

In this study, the initial transformation of gold seed on indium tin oxide (ITO) surfaces was investigated. Gold nanoparticles (AuNPs) grew on ITO surfaces using a seed-mediated method. The reduction rate of gold(I) salt and the shapes of AuNPs were affected by the concentration of cetyltrimethylammonium bromide (CTAB). Gold nanorods (AuNRs) appeared when the CTAB concentration was above 75 mM, and the shapes agreed with the dispersing state of CTAB micelles in solution. CTAB was replaced by cetyltrimethylammonium chloride (CTAC) in the growth procedure. Only small gold nanospheres (AuNSs) appeared when the CTAC concentration was increased. This result agreed with the dispersing state of CTAC micelles in solution and implied that gold salts were not free in either CTAB or CTAC solution. A red shift of 14 nm in the UV–vis spectra of AuBr4− was found in the presence of CTAB, and furthermore, AuBr2− became stable. This indicated that the gold salt strongly bound to cetyltrimethylammonium ion (CTA+) and was c...