Electrochemical formation and characterization of Au nanostructures on a highly ordered pyrolytic graphite surface

J. J. ARROYO GÓMEZ; S. G. GARCIA; C. ZUBIETA; R. M. FERULLO

APPLIED SURFACE SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 363 p. 356 - 362

0169-4332

The electrochemical formation of Au nanoparticles on a highly ordered pyrolytic graphite (HOPG)substrate using conventional electrochemical techniques and ex-situ AFM is reported. From the poten-tiostatic current transients studies, the Au electrodeposition process on HOPG surfaces was described,within the potential range considered, by a model involving instantaneous nucleation and diffusion con-trolled 3D growth, which was corroborated by the microscopic analysis. Initially, three-dimensional (3D)hemispherical nanoparticles distributed on surface defects (step edges) of the substrate were observed,with increasing particle size at more negative potentials. The double potential pulse technique allowedthe formation of rounded deposits at low deposition potentials, which tend to form lines of nuclei alignedin defined directions leading to 3D ordered structures. By choosing suitable nucleation and growth pulses,one-dimensional (1D) deposits were possible, preferentially located on step edges of the HOPG substrate.Quantum-mechanical calculations confirmed the tendency of Au atoms to join selectively on surfacedefects, such as the HOPG step edges, at the early stages of Au electrodeposition.