Electrochemical route for the fabrication of alkanethiolate-capped gold nanoparticles

Nearly monodispersed gold nanoparticles (NPs) of a few nanometers were fabricated and immobilized simultaneously on silicon surface by the galvanostatic reduction of ${\mathrm{HAuCl}}_4$ in the presence of dodecanethiol. X-ray absorption spectra at both sulfur $K$ edge and gold $L_3$ edge confirm the existence of the alkanethiolate-protected Au NPs and reveal their structural and bonding characteristics. Alkanethiolate-capped Au NPs were also successfully fabricated, with the same technique, on porous silicon, a functional substrate with high surface area. The hybrid thiol-capping/electrodeposition method reported here offers an attractive approach to the fabrication of highly stable gold NPs on various functional substrates with a simple, fast, and easily controlled experimental procedure.