Fabrication of covalent SAM/Au nanoparticle/boron-doped diamond configurations with a sequential self-assembly method

An attempt was made to make use of chemical modification of the diamond surface to control the adsorption of Au nanoparticles (AuNPs) on this surface via self-assembly. AuNPs prepared with a citrate reduction method (c-AuNP) and mercaptoacetic acid (MAA)-modified AuNPs (MAA-AuNP) were not adsorbed onto hydrogen-terminated and oxygen-terminated boron-doped diamond (BDD) surfaces. On the other hand, c-AuNP and MAA-AuNP were found to be adsorbed in a homogeneous, well-dispersed fashion on NH₂-terminated and SH-terminated BDDs prepared with the silane coupling method. It was also found that the adsorption of c-AuNP on SH-BDD was more stable than that on NH₂-BDD versus immersion in various thiol aqueous solutions used to form self-assembled monolayers (SAMs) on the Au surface, without desorption of the AuNP from the BDD surface. Immersion of the c-AuNP/SH-BDD sample in a ferrocenylalkanethiol/ ethanol solution was found, by cyclic voltammetry, to result in chemisorption of the thiol to the Au surface. Facile electronic communication through the ferrocenyl moiety to the BDD substrate suggests that SAM/AuNP/BDD configurations based on SH-BDD fabricated by a self-assembly method can be applied to possible molecular electronic and electrochemical devices.