Surface observation for seed-mediated growth attachment of gold nanoparticles on a glassy carbon substrate.

A seed-mediated growth method for surface modification was applied to the attachment of gold nanoparticles (AuNPs) to glassy carbon (GC) surfaces. By simply immersing a GC plate at first into a seed solution containing 4 nm Au nano-seed particles and then into a growth solution containing HAuCl(4), ascorbic acid and cetyltrimethyammonium bromide, AuNPs could be successfully attached to the GC surface via the growth of nanoparticles. A possible control of the size and density of AuNPs on GC was examined by observing surface images with a field-emission scanning electron microscope (FE-SEM) after several preparations with different immersion times. Compared with previous results on the growth of AuNPs on indium tin oxide (ITO) surfaces, it was characteristic that the AuNPs attached to GC surfaces exhibited smaller size and higher density as well as a flatter and non-crystal-like morphology. In addition, for performing the dense attachment of regular nano-sized AuNPs on GC surfaces, immersion for 2 h into the growth solution was sufficient. Longer immersion for 24 h caused an irregular growth of bold Au micro-crystals, while 24 h was necessary in the case of AuNPs on ITO surfaces. Shorter seeding and growth times were found to be effective for a sparse attachment of smaller Au nanoparticles whose size was ca. 20 nm. It was clarified that the seed-mediated growth method for surface modification was valid for fabricating a nanointerface composed of AuNPs on GC surfaces.