Electrodeposition of gold nanoparticles on aryl diazonium monolayer functionalized HOPG surfaces

Abstract

Gold nanoparticles electrodeposition on a modified HOPG surface with a monolayer organic film based on aryl diazonium chemistry has been studied. This organic monolayer is electrochemically grown with the use of 2,2-diphenyl-1picrylhydrazyl (DPPH), a radical scavenger. The electrodeposition of gold on this modified surface results highly favored resulting in a AuNPs surface density comparable to that found on glassy carbon. AuNPs grow only in the areas covered by the organic monolayer leaving free clean HOPG zones. A progressive mechanism for the nucleation and growth is followed giving AuNPs hemispherical shaped, homogeneously distributed on the surface and of sizes that can be well controlled by the electrodeposition applied potential. By using AFM, C-AFM and electrochemical measurements with the aid of two redox probes, namely Fe(CN)6 4-/ Fe(CN)6 3- and dopamine, relevant results about the electrochemical modified surface as well as the gold nanoparticles electrodeposited on them are obtained.